This document discusses infrared (IR) spectroscopy. It provides information on the basic principles of IR spectroscopy, sample preparation techniques, instrumentation including dispersive and Fourier transform IR spectrometers, data analysis and interpretation. Key points covered include how IR spectroscopy can be used to identify functional groups in molecules based on their characteristic absorption frequencies, and that each compound produces a unique IR spectrum that can be considered a "fingerprint" of its structure.
The coupling constant is the distance between peaks in a multiplet in NMR spectroscopy. It is measured in Hertz and does not depend on external magnetic field strength. The value of the coupling constant provides information to distinguish multiplets and can indicate structural features like cis/trans isomers. Coupling occurs between protons close in space, known as geminal, vicinal, and sometimes long-range coupling over several bonds. The coupling constant is affected by factors like bond angle, dihedral angle, and electronegativity of substituents.
1. The document discusses infrared (IR) spectroscopy, which involves using IR radiation to analyze chemical bonds and functional groups in molecules.
2. IR spectroscopy works by measuring the absorption of IR frequencies by a sample; different functional groups absorb characteristic frequencies allowing identification.
3. For a vibration to be IR active, it must involve a change in the molecule's dipole moment as the bonds vibrate. Stretching and bending vibrations between bonds can both be IR active.
The document discusses the DEPT NMR experiment, which is used to determine the multiplicities of carbon-13 atoms. It introduces the DEPT experiment as using polarization transfer to provide more information than traditional off-resonance decoupled experiments. DEPT experiments are performed at different pulse angles (45°, 90°, 135°) to distinguish between CH, CH2, and CH3 groups. Examples of DEPT spectra are provided for isoamyl acetate and diethyl phthalate to demonstrate the peaks observed for different carbon types. The document provides an overview of the DEPT experiment and how it improves upon previous carbon NMR techniques.
The document discusses the nuclear Overhauser effect (NOE), which occurs when two protons are in close proximity within a molecule. Irradiating one proton perturbs its spin distribution and affects the relaxation of the other nearby proton. This causes the intensity of the other proton's signal to increase or decrease, indicating their proximity. The NOE provides information about molecular geometry without requiring coupling between nuclei and can reveal which protons are near each other in a structure.
This document discusses 19F NMR spectroscopy. It begins by explaining that 19F NMR can be used to identify fluorine-containing compounds and describes the nuclear properties of 19F that make it responsive to NMR measurements. It then discusses the reference standards used for 19F NMR, solvent effects, isotopic effects, coupling constants, and provides examples of spin systems and virtual coupling. The document also discusses organofluorine compounds and their applications as well as some environmental and health issues.
NOESY (Nuclear Overhauser Effect Spectroscopy) is a 2D NMR technique used to identify nuclear spins undergoing cross-relaxation and measure their rates. It provides information about which proton resonances are from protons close in space. NOESY experiments exploit the nuclear Overhauser effect to observe through-space dipolar couplings. One application is in protein NMR to assign structures by sequential walking. It is useful for determining the stereochemistry of biomolecules in solution.
The document discusses NMR spectroscopy of various nuclei and their applications to inorganic molecules. It provides details on the natural abundance, spin, magnetic moment, and magnetogyric ratio of common NMR-active nuclei such as 1H, 2H, 11B, 13C, 17O, 19F, 29Si, and 31P. It then discusses the applications of 19F, 29Si, and 31P NMR spectroscopy for structure elucidation of inorganic molecules. Examples are provided to illustrate how NMR chemical shifts and coupling constants can provide information about functional groups, molecular structures, and stereochemistry.
The coupling constant is the distance between peaks in a multiplet in NMR spectroscopy. It is measured in Hertz and does not depend on external magnetic field strength. The value of the coupling constant provides information to distinguish multiplets and can indicate structural features like cis/trans isomers. Coupling occurs between protons close in space, known as geminal, vicinal, and sometimes long-range coupling over several bonds. The coupling constant is affected by factors like bond angle, dihedral angle, and electronegativity of substituents.
1. The document discusses infrared (IR) spectroscopy, which involves using IR radiation to analyze chemical bonds and functional groups in molecules.
2. IR spectroscopy works by measuring the absorption of IR frequencies by a sample; different functional groups absorb characteristic frequencies allowing identification.
3. For a vibration to be IR active, it must involve a change in the molecule's dipole moment as the bonds vibrate. Stretching and bending vibrations between bonds can both be IR active.
The document discusses the DEPT NMR experiment, which is used to determine the multiplicities of carbon-13 atoms. It introduces the DEPT experiment as using polarization transfer to provide more information than traditional off-resonance decoupled experiments. DEPT experiments are performed at different pulse angles (45°, 90°, 135°) to distinguish between CH, CH2, and CH3 groups. Examples of DEPT spectra are provided for isoamyl acetate and diethyl phthalate to demonstrate the peaks observed for different carbon types. The document provides an overview of the DEPT experiment and how it improves upon previous carbon NMR techniques.
The document discusses the nuclear Overhauser effect (NOE), which occurs when two protons are in close proximity within a molecule. Irradiating one proton perturbs its spin distribution and affects the relaxation of the other nearby proton. This causes the intensity of the other proton's signal to increase or decrease, indicating their proximity. The NOE provides information about molecular geometry without requiring coupling between nuclei and can reveal which protons are near each other in a structure.
This document discusses 19F NMR spectroscopy. It begins by explaining that 19F NMR can be used to identify fluorine-containing compounds and describes the nuclear properties of 19F that make it responsive to NMR measurements. It then discusses the reference standards used for 19F NMR, solvent effects, isotopic effects, coupling constants, and provides examples of spin systems and virtual coupling. The document also discusses organofluorine compounds and their applications as well as some environmental and health issues.
NOESY (Nuclear Overhauser Effect Spectroscopy) is a 2D NMR technique used to identify nuclear spins undergoing cross-relaxation and measure their rates. It provides information about which proton resonances are from protons close in space. NOESY experiments exploit the nuclear Overhauser effect to observe through-space dipolar couplings. One application is in protein NMR to assign structures by sequential walking. It is useful for determining the stereochemistry of biomolecules in solution.
The document discusses NMR spectroscopy of various nuclei and their applications to inorganic molecules. It provides details on the natural abundance, spin, magnetic moment, and magnetogyric ratio of common NMR-active nuclei such as 1H, 2H, 11B, 13C, 17O, 19F, 29Si, and 31P. It then discusses the applications of 19F, 29Si, and 31P NMR spectroscopy for structure elucidation of inorganic molecules. Examples are provided to illustrate how NMR chemical shifts and coupling constants can provide information about functional groups, molecular structures, and stereochemistry.
This document provides an overview of nuclear magnetic resonance spectroscopy (NMR) focusing on Carbon-13 (13C) NMR. It defines NMR and explains the principles of how atomic nuclei absorb energy from radiofrequency fields in a magnetic field. The summary discusses key aspects of 13C NMR including that 13C is difficult to detect due to its low natural abundance, advantages over 1H NMR, factors affecting chemical shifts, techniques to simplify spectra like decoupling, and applications like DEPT NMR to determine functional groups.
Shielding effect,effect of chemical exchange,hydrogen bondingSumeetJha12
This document summarizes key concepts related to NMR spectroscopy, including shielding effect, hydrogen bonding, and chemical exchange. It describes how the shielding effect causes some nuclei to experience less of an external magnetic field, requiring a higher frequency for resonance. Hydrogen bonding causes deshielding and higher chemical shift values as electron density around protons decreases. Chemical exchange refers to nuclei switching environments, which can lead to sharp, broad, or coupled peaks depending on the exchange rate relative to peak separation.
The document discusses Fourier-transform nuclear magnetic resonance (FT-NMR) spectroscopy. It provides an introduction to Fourier transforms and their use in converting time domain NMR spectra to frequency domain spectra. It describes the components of an FT-NMR instrument, including an RF transmitter coil, magnet, receiver coil, and computer. Key advantages of FT-NMR are its dramatic increase in sensitivity over continuous wave NMR, allowing detection of samples under 5 mg, and its ability to rapidly provide high signal-to-noise ratio spectra.
This document discusses overtones and Fermi resonance in infrared spectroscopy. It defines overtones as absorptions that occur at integral multiples of the fundamental frequency, such as a band at 1000 cm-1 accompanying a fundamental at 500 cm-1. Fermi resonance occurs when a fundamental and overtone band have similar energies, causing them to interact and shift in intensity and frequency. This can result in a "Fermi doublet" with one band increasing while the other decreases in energy. The document provides examples of overtones and Fermi resonance in infrared spectra.
The document discusses the McLafferty rearrangement, which is a reaction observed using mass spectrometry. The rearrangement involves a carbonyl compound undergoing cleavage of alpha and gamma bonds, resulting in an enol radical cation and a neutral alkene fragment. Fred McLafferty first observed this reaction using mass spectrometry. The reaction proceeds through a six-membered ring transition state and has specific requirements for the carbonyl compound. Examples of compounds undergoing the rearrangement include 2-hexanone and hexanoic acid.
Spin-spin splitting is a term that describes the magnetic interactions between neighbouring, non-equivalent NMR-active nuclei which will cause splitting of NMR signal. This splitting occurs because of the interaction between neighboring hydrogen nuclei, and results in multiplets rather than single peaks in the NMR spectrum. The number of peaks in the multiplet is predicted by the "n+1" rule, where n is the number of neighboring equivalent protons. Common splitting patterns include doublets, triplets and quartets.
It contains what are the shift reagents, and how they will use in NMR spectroscopy. It includes lanthanide shift reagents and their effect using NMR spectroscopy. It has mostly used shift reagents like Europium and their importance. paramagnetic species that affect the NMR spectra are also explained in detail. What are contact shift and pseudo-contact shift also explained. It contains what are the chiral shift reagent, and the advantages, and disadvantages of lanthanide shift reagents. Reference books are also included.
Auger Electron Spectroscopy (AES) uses a focused electron beam to eject inner shell electrons from the surface of a sample. The vacancies are filled by higher-energy electrons, emitting characteristic "Auger electrons" that can be analyzed to determine the elemental composition of the top few atomic layers. The key components of an AES system are an electron gun, electron energy analyzer, electron detector, and ultra-high vacuum environment. AES provides surface sensitivity, elemental analysis, and depth profiling capabilities. Limitations include inability to analyze non-conductive samples and lack of hydrogen/helium detection.
This document describes continuous wave (CW) NMR spectroscopy. It explains that CW-NMR uses a fixed magnetic field and varies the frequency coil current to achieve resonance signals. A typical CW spectrometer contains a sample tube spun between the poles of a powerful magnet. Radio frequency is broadcast into the sample while a receiver coil monitors the absorbed energy. By varying the magnetic field or radio frequency, an NMR spectrum is acquired showing signals from different proton types in the sample. While offering routine 1H NMR studies, CW spectroscopy has limitations such as low sensitivity, requirement for concentrated samples, and production of high noise.
Vibrational frequencies can shift from normal values due to several factors:
1) Coupled vibrations occur when bond vibrations interact, causing asymmetric and symmetric stretches at different frequencies than isolated bonds.
2) Fermi resonance involves coupling between fundamental and overtone vibrations, splitting peaks between the two modes.
3) Hydrogen bonding lowers frequencies as it strengthens interactions between donor and acceptor groups. Stronger bonding yields greater shifts to lower frequencies.
4) Electronic effects like induction, mesomerism, and field effects influence frequencies by strengthening or weakening bonds.
1. 1D and 2D NMR techniques are described. 1D NMR involves applying a 90 degree pulse to a sample in a magnetic field and measuring the resulting signal. 2D NMR applies two 90 degree pulses separated by a short delay and measures two signals, which are Fourier transformed to provide frequency information in two dimensions.
2. 2D NMR was first proposed by Jean Jeener and provides more structural information than 1D NMR as it plots data on two frequency axes rather than one. It involves collecting a series of 1D NMR spectra with varying pulse delays and further Fourier transforming these signals.
3. The document provides details on the principles, pulse sequences, and names of 1D and 2D NMR techniques.
This document presents information on the Tanabe-Sugano diagram, which is used in coordination chemistry to predict absorptions in the UV-visible and IR spectra of coordination compounds. It was developed by Yukito Tanabe and Satoru Sugano in 1954 to explain the absorption spectra of octahedral complex ions. The diagram plots orbital energy as a function of the Racah parameter B versus the ligand field splitting parameter Δo/B. It can be used to determine the ordering of electronic states and predict possible electronic transitions based on parameters like Δo, Racah parameters B and C, symmetry rules, and term symbols of electronic configurations. The diagram has advantages over earlier Orgel diagrams in that it can be applied to
Lanthanide shift reagents are used in NMR spectroscopy to induce shifts in proton resonances. Europium complexes are commonly used shift reagents that cause downfield shifts, while cerium complexes cause upfield shifts. The amount of shift depends on the distance between the metal ion and protons, and the concentration of the shift reagent. Shift reagents simplify NMR spectra by resolving overlapping peaks and providing more detailed information about molecular structures. They are especially useful for distinguishing geometric isomers.
1. Nuclear magnetic resonance (NMR) spectroscopy exploits the magnetic properties of atomic nuclei to study the physical, chemical, and biological properties of matter.
2. Key developments in NMR history include the first observations of NMR in solutions and solids in 1945, and the development of Fourier transform NMR and 2D NMR in the 1960s-1970s, which enabled the determination of protein structures by NMR.
3. NMR spectroscopy provides information about the number, type, and neighboring environment of nuclei in a molecule based on signals in the NMR spectrum.
Nmr nuclear magnetic resonance spectroscopyJoel Cornelio
Basics of NMR. Suitable for UG and PG courses.
Includes principle, instrumentation, solvents. chemical shift and factors affecting it. Some problems. resolving agents, coupling constant and much more
Nuclear magnetic resonance (NMR) spectroscopyVK VIKRAM VARMA
SPECTROSCOPY
NMR SPECTROSCOPY
HISTORY
THEORY
PRINCIPLE
INSTRUMENTATION
SOLVENTS USED IN NMR(PROTON NMR)
CHEMICAL SHIFT
FACTORS AFFECTING CHEMICAL SHIFT
RELAXATION PROCESS
SPIN-SPIN COUPLING
푛+1 RULE
NMR SIGNALS IN VARIOUS COMPOUNDS
COUPLING CONSTANT
NUCLEAR MAGNETIC DOUBLE RESONANCE/ SPIN DECOUPLING
FT-NMR
ADVANTAGES & DISADVANTAGES
APPLICATIONS
REFERENCE
A ppt compiled by Yaseen Aziz Wani pursuing M.Sc Chemistry at University of Kashmir, J&K, India and Naveed Bashir Dar, a student of electrical engg. at NIT Srinagar.
Warm regards to Munnazir Bashir also for providing us with refreshing tea while we were compiling ppt.
Principle and working of Nmr spectroscopyArpitSuralkar
NMR spectroscopy involves measuring the absorption of electromagnetic radiation in the radio frequency region by atomic nuclei. It is used to study nuclei such as hydrogen-1, carbon-13, and nitrogen-15. The principle involves atomic nuclei with spin precessing at their Larmor frequency when placed in an external magnetic field. The Larmor frequency depends on the magnetic field strength according to the Larmor equation. Fourier transform NMR provides advantages over continuous wave NMR by being more sensitive and requiring less time for scanning.
IR spectroscopy provides a spectrum that contains absorption bands that can determine the structure of organic compounds. It works by detecting the frequencies at which molecules vibrate and absorb infrared radiation. The most useful infrared region for analyzing organic compounds has wavelengths from 4000 to 400 cm-1. When infrared radiation is absorbed by a molecule, it causes bonds to stretch or bend based on their vibrational modes. For a vibration to be detected in the infrared spectrum, it must cause a change in the dipole moment of the molecule.
This document provides an overview of nuclear magnetic resonance spectroscopy (NMR) focusing on Carbon-13 (13C) NMR. It defines NMR and explains the principles of how atomic nuclei absorb energy from radiofrequency fields in a magnetic field. The summary discusses key aspects of 13C NMR including that 13C is difficult to detect due to its low natural abundance, advantages over 1H NMR, factors affecting chemical shifts, techniques to simplify spectra like decoupling, and applications like DEPT NMR to determine functional groups.
Shielding effect,effect of chemical exchange,hydrogen bondingSumeetJha12
This document summarizes key concepts related to NMR spectroscopy, including shielding effect, hydrogen bonding, and chemical exchange. It describes how the shielding effect causes some nuclei to experience less of an external magnetic field, requiring a higher frequency for resonance. Hydrogen bonding causes deshielding and higher chemical shift values as electron density around protons decreases. Chemical exchange refers to nuclei switching environments, which can lead to sharp, broad, or coupled peaks depending on the exchange rate relative to peak separation.
The document discusses Fourier-transform nuclear magnetic resonance (FT-NMR) spectroscopy. It provides an introduction to Fourier transforms and their use in converting time domain NMR spectra to frequency domain spectra. It describes the components of an FT-NMR instrument, including an RF transmitter coil, magnet, receiver coil, and computer. Key advantages of FT-NMR are its dramatic increase in sensitivity over continuous wave NMR, allowing detection of samples under 5 mg, and its ability to rapidly provide high signal-to-noise ratio spectra.
This document discusses overtones and Fermi resonance in infrared spectroscopy. It defines overtones as absorptions that occur at integral multiples of the fundamental frequency, such as a band at 1000 cm-1 accompanying a fundamental at 500 cm-1. Fermi resonance occurs when a fundamental and overtone band have similar energies, causing them to interact and shift in intensity and frequency. This can result in a "Fermi doublet" with one band increasing while the other decreases in energy. The document provides examples of overtones and Fermi resonance in infrared spectra.
The document discusses the McLafferty rearrangement, which is a reaction observed using mass spectrometry. The rearrangement involves a carbonyl compound undergoing cleavage of alpha and gamma bonds, resulting in an enol radical cation and a neutral alkene fragment. Fred McLafferty first observed this reaction using mass spectrometry. The reaction proceeds through a six-membered ring transition state and has specific requirements for the carbonyl compound. Examples of compounds undergoing the rearrangement include 2-hexanone and hexanoic acid.
Spin-spin splitting is a term that describes the magnetic interactions between neighbouring, non-equivalent NMR-active nuclei which will cause splitting of NMR signal. This splitting occurs because of the interaction between neighboring hydrogen nuclei, and results in multiplets rather than single peaks in the NMR spectrum. The number of peaks in the multiplet is predicted by the "n+1" rule, where n is the number of neighboring equivalent protons. Common splitting patterns include doublets, triplets and quartets.
It contains what are the shift reagents, and how they will use in NMR spectroscopy. It includes lanthanide shift reagents and their effect using NMR spectroscopy. It has mostly used shift reagents like Europium and their importance. paramagnetic species that affect the NMR spectra are also explained in detail. What are contact shift and pseudo-contact shift also explained. It contains what are the chiral shift reagent, and the advantages, and disadvantages of lanthanide shift reagents. Reference books are also included.
Auger Electron Spectroscopy (AES) uses a focused electron beam to eject inner shell electrons from the surface of a sample. The vacancies are filled by higher-energy electrons, emitting characteristic "Auger electrons" that can be analyzed to determine the elemental composition of the top few atomic layers. The key components of an AES system are an electron gun, electron energy analyzer, electron detector, and ultra-high vacuum environment. AES provides surface sensitivity, elemental analysis, and depth profiling capabilities. Limitations include inability to analyze non-conductive samples and lack of hydrogen/helium detection.
This document describes continuous wave (CW) NMR spectroscopy. It explains that CW-NMR uses a fixed magnetic field and varies the frequency coil current to achieve resonance signals. A typical CW spectrometer contains a sample tube spun between the poles of a powerful magnet. Radio frequency is broadcast into the sample while a receiver coil monitors the absorbed energy. By varying the magnetic field or radio frequency, an NMR spectrum is acquired showing signals from different proton types in the sample. While offering routine 1H NMR studies, CW spectroscopy has limitations such as low sensitivity, requirement for concentrated samples, and production of high noise.
Vibrational frequencies can shift from normal values due to several factors:
1) Coupled vibrations occur when bond vibrations interact, causing asymmetric and symmetric stretches at different frequencies than isolated bonds.
2) Fermi resonance involves coupling between fundamental and overtone vibrations, splitting peaks between the two modes.
3) Hydrogen bonding lowers frequencies as it strengthens interactions between donor and acceptor groups. Stronger bonding yields greater shifts to lower frequencies.
4) Electronic effects like induction, mesomerism, and field effects influence frequencies by strengthening or weakening bonds.
1. 1D and 2D NMR techniques are described. 1D NMR involves applying a 90 degree pulse to a sample in a magnetic field and measuring the resulting signal. 2D NMR applies two 90 degree pulses separated by a short delay and measures two signals, which are Fourier transformed to provide frequency information in two dimensions.
2. 2D NMR was first proposed by Jean Jeener and provides more structural information than 1D NMR as it plots data on two frequency axes rather than one. It involves collecting a series of 1D NMR spectra with varying pulse delays and further Fourier transforming these signals.
3. The document provides details on the principles, pulse sequences, and names of 1D and 2D NMR techniques.
This document presents information on the Tanabe-Sugano diagram, which is used in coordination chemistry to predict absorptions in the UV-visible and IR spectra of coordination compounds. It was developed by Yukito Tanabe and Satoru Sugano in 1954 to explain the absorption spectra of octahedral complex ions. The diagram plots orbital energy as a function of the Racah parameter B versus the ligand field splitting parameter Δo/B. It can be used to determine the ordering of electronic states and predict possible electronic transitions based on parameters like Δo, Racah parameters B and C, symmetry rules, and term symbols of electronic configurations. The diagram has advantages over earlier Orgel diagrams in that it can be applied to
Lanthanide shift reagents are used in NMR spectroscopy to induce shifts in proton resonances. Europium complexes are commonly used shift reagents that cause downfield shifts, while cerium complexes cause upfield shifts. The amount of shift depends on the distance between the metal ion and protons, and the concentration of the shift reagent. Shift reagents simplify NMR spectra by resolving overlapping peaks and providing more detailed information about molecular structures. They are especially useful for distinguishing geometric isomers.
1. Nuclear magnetic resonance (NMR) spectroscopy exploits the magnetic properties of atomic nuclei to study the physical, chemical, and biological properties of matter.
2. Key developments in NMR history include the first observations of NMR in solutions and solids in 1945, and the development of Fourier transform NMR and 2D NMR in the 1960s-1970s, which enabled the determination of protein structures by NMR.
3. NMR spectroscopy provides information about the number, type, and neighboring environment of nuclei in a molecule based on signals in the NMR spectrum.
Nmr nuclear magnetic resonance spectroscopyJoel Cornelio
Basics of NMR. Suitable for UG and PG courses.
Includes principle, instrumentation, solvents. chemical shift and factors affecting it. Some problems. resolving agents, coupling constant and much more
Nuclear magnetic resonance (NMR) spectroscopyVK VIKRAM VARMA
SPECTROSCOPY
NMR SPECTROSCOPY
HISTORY
THEORY
PRINCIPLE
INSTRUMENTATION
SOLVENTS USED IN NMR(PROTON NMR)
CHEMICAL SHIFT
FACTORS AFFECTING CHEMICAL SHIFT
RELAXATION PROCESS
SPIN-SPIN COUPLING
푛+1 RULE
NMR SIGNALS IN VARIOUS COMPOUNDS
COUPLING CONSTANT
NUCLEAR MAGNETIC DOUBLE RESONANCE/ SPIN DECOUPLING
FT-NMR
ADVANTAGES & DISADVANTAGES
APPLICATIONS
REFERENCE
A ppt compiled by Yaseen Aziz Wani pursuing M.Sc Chemistry at University of Kashmir, J&K, India and Naveed Bashir Dar, a student of electrical engg. at NIT Srinagar.
Warm regards to Munnazir Bashir also for providing us with refreshing tea while we were compiling ppt.
Principle and working of Nmr spectroscopyArpitSuralkar
NMR spectroscopy involves measuring the absorption of electromagnetic radiation in the radio frequency region by atomic nuclei. It is used to study nuclei such as hydrogen-1, carbon-13, and nitrogen-15. The principle involves atomic nuclei with spin precessing at their Larmor frequency when placed in an external magnetic field. The Larmor frequency depends on the magnetic field strength according to the Larmor equation. Fourier transform NMR provides advantages over continuous wave NMR by being more sensitive and requiring less time for scanning.
IR spectroscopy provides a spectrum that contains absorption bands that can determine the structure of organic compounds. It works by detecting the frequencies at which molecules vibrate and absorb infrared radiation. The most useful infrared region for analyzing organic compounds has wavelengths from 4000 to 400 cm-1. When infrared radiation is absorbed by a molecule, it causes bonds to stretch or bend based on their vibrational modes. For a vibration to be detected in the infrared spectrum, it must cause a change in the dipole moment of the molecule.
This document provides an overview of infrared spectroscopy. It discusses the principle, which is that IR radiation causes molecular vibrations when absorbed by bonds with a change in dipole moment. Factors affecting absorption frequencies and intensities are described. The instrumentation of an FTIR spectrometer is explained, including its source, interferometer, sample handling, and detectors. Various sample preparation techniques for analyzing solids, liquids, and gases are also outlined.
Infrared spectroscopy analyzes the absorption of infrared radiation by molecules to determine their structure. When IR radiation interacts with a molecule, it can cause the bonds and atoms within the molecule to vibrate. For a vibration to be IR active, it must cause a change in the molecule's dipole moment. IR spectroscopy is useful for identifying organic functional groups and determining molecular structure. It has applications in pharmaceutical analysis including identification of drugs and excipients, and quality control of drug formulations.
This document discusses various analytical techniques including UV-visible spectroscopy, IR spectroscopy, colorimetry, flame photometry, and atomic absorption spectroscopy. It begins by introducing Beer-Lambert's law and its applications in quantitative analysis using spectrophotometry. It then provides details on the principles, instrumentation, and applications of UV-visible spectroscopy and IR spectroscopy. It describes how these techniques can be used to determine functional groups, identify organic compounds, and study molecular structure. The document also discusses the principles and applications of colorimetry in quantitative analysis of colored solutions.
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemicals
Infrared spectroscopy uses infrared light to study vibrational and rotational modes of molecules. It can be used to identify functional groups and study molecular structure. Infrared light causes bonds to vibrate, with different vibrations absorbing different wavelengths. Samples can be analyzed as gases, liquids between NaCl or KBr plates, or solids mixed with KBr. Dispersive and Fourier transform instruments are used to collect infrared spectra, which provide information on molecular structure, purity, and reaction progress. Infrared spectroscopy is widely used for organic compound analysis in research and industry.
This document provides an overview of infrared spectroscopy. It discusses the principle that infrared spectroscopy involves absorption of infrared radiation which causes vibrational transitions in molecules. The instrumentation involves an infrared source, sample holder, and detector. Applications include identifying functional groups in organic molecules, determining drug formulations, and analyzing biological samples like urine.
This document provides an overview of infrared spectroscopy. It discusses the principle that infrared spectroscopy involves absorption of infrared radiation which causes vibrational transitions in molecules. The instrumentation involves an infrared source, sample holder, and detector. Applications include identifying functional groups in organic molecules, determining drug formulations, and analyzing biological samples like urine.
Given:
A = Absorbance = 1
l = Path length = 2 cm
ε = Molar absorptivity = 2x10^4 L/mol.cm
Using the Beer-Lambert's law:
A = ε x c x l
1 = 2x10^4 x c x 2
c = 1 / (2x10^4 x 2)
c = 2.5x10^-5 mol/L
So, the concentration of the substance is 2.5x10^-5 mol/L.
Unit 5 Spectroscopic Techniques-converted (1) (1).pdfSurajShinde558909
Spectroscopy is the study of interaction of electromagnetic radiation with matter. Spectroscopic techniques are based on measurement of electromagnetic radiation emitted or absorbed by a sample. The main spectroscopic techniques discussed are UV-Visible spectroscopy and Infrared (IR) spectroscopy. UV-Visible spectroscopy provides information about double and triple bonds in molecules, while IR spectroscopy provides information about functional groups. Both techniques can be used for qualitative and quantitative analysis of compounds.
FTIR SPECTROSCOPY,
Principle, Theory, Instrumentation and Application in Pharmaceutical Industry
IR Spectroscopy- Absorption Theory
Type of Vibrations & Vibration Energy level
FTIR Spectrophotometer-Instrumentation
Operation of the Spectrophotometer
Qualification & Calibration
IR Absorption by Organic compounds
Application
FDA citation in FTIR Analysis-Pharmaceutical Industries
Infrared spectroscopy is a technique that uses infrared light to analyze chemical bonding and molecular structure. It works by detecting the frequencies at which molecules vibrate or rotate when exposed to infrared radiation. The document discusses the principles of infrared spectroscopy, including how molecular vibrations can be excited when their frequency matches the frequency of infrared radiation. It also covers factors that determine infrared absorption frequencies and the types of molecular vibrations that are infrared active.
Infrared spectroscopy is a technique that uses infrared light to analyze chemical bonding and structure. It works by measuring the frequencies at which molecules vibrate and absorb infrared radiation. Modern infrared instruments use a Fourier transform method with an interferometer to produce an infrared spectrum that acts as a molecular "fingerprint". Infrared spectroscopy is useful for identifying unknown materials, determining molecular structure of organic and inorganic compounds, and studying molecular interactions.
Infrared spectroscopy can be used to analyze organic molecules by detecting the vibrational frequencies of their covalent bonds. When a molecule is exposed to infrared radiation that matches the frequency of one of its vibrational modes, it will absorb that radiation. Different functional groups, like carbonyls, alcohols, and alkenes, absorb infrared radiation at characteristic frequencies. By examining the absorption peaks in a molecule's infrared spectrum, chemists can determine which functional groups are present and identify unknown compounds.
IR Spectroscopy with detailed introductionnivedithag131
This document provides a seminar on infrared spectroscopy, covering the introduction, principle, and theory of infrared spectroscopy. It discusses the different types of vibrations molecules can undergo and how this relates to their infrared absorption. Factors that influence vibrational frequencies like coupled vibrations, hydrogen bonding, and electronic effects are explained. The relationship between wavelength and wave number is defined. The document also covers the degrees of freedom in molecules and how this relates to the number of fundamental absorption bands.
1. Infrared spectroscopy involves measuring the absorption of infrared radiation by a sample and plotting it as a function of wavelength or wavenumber.
2. Infrared radiation causes transitions between vibrational and rotational energy levels in molecules, allowing the characteristic vibrations of bonds to be observed.
3. An infrared spectrometer consists of an infrared source, sample holder, monochromator to separate wavelengths, detector, and recorder. It measures the infrared absorption spectrum of a sample.
Infrared spectroscopy involves using infrared radiation to study molecular vibrations. When the frequency of infrared radiation matches the natural vibrational frequency of a molecule, absorption occurs, exciting the molecule to a higher vibrational state. Each bond in a molecule has characteristic vibrational frequencies that depend on the masses of the atoms and strength of the bonds. Infrared spectroscopy can be used to identify organic compounds based on their unique absorption frequencies, determine functional groups present, and study reactions and phenomena like hydrogen bonding and keto-enol tautomerism.
IR SPECTROSCOPY, INTRODUCTION, PRINCIPLE, THEORY, FATE OF ABSORBED RADIATION, FERMI RESONANCE, FINGERPRINT REGION, VIBRATIONS, FACTORS AFFECTING ABSORPTION OF IR RADIATION, SAMPLING TECHNIQUES, APPLICATIONS OF IR SPECTROSCOPY.
Infrared Spectroscopy and UV-Visible spectroscopyPreeti Choudhary
Instrumentation of Infrared Spectroscopy and UV-Vis spectroscopy
Discuss the fundamentals and concepts behind Infrared and UV-Vis spectroscopy.
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This document discusses various analytical techniques used in spectroscopy. It describes spectroscopy as the study of interaction between electromagnetic radiation and matter. There are different types of spectroscopy including absorption, emission, and scattering spectroscopy. Specific techniques are used to identify unknown substances, predict behavior of new materials, and qualitatively or quantitatively analyze chemical composition. The document provides examples of spectroscopy techniques and their applications in areas like determining organic structures and quantifying metal ions.
This document provides an overview of polymer chemistry course content including synthesis of polymers, characterization of polymer molecules, molecular weight determination, and polymer structures. It discusses different types of polymers such as thermoplastics, thermosets, elastomers, and their properties. The key topics covered are polymerization reactions, molecular weight averages, polymer configurations including isotactic, syndiotactic and atactic, nomenclature, and the importance of molecular weight on polymer properties.
The document discusses viscosity measurement using a Ubbelohde viscometer. It measures the flow time of a dilute polymer solution dropping between two levels to calculate viscosity values like relative viscosity, specific viscosity, reduced viscosity, and inherent viscosity. These viscosity designations can be related to the molecular weight of the polymer using equations like the Mark-Houwink-Sakurada equation. Precise viscosity measurements require a clean vertical viscometer and constant temperature control.
This document provides information about fatty acids and triglycerides. It discusses the structure, properties, and reactions of fatty acids, including their length, degree of saturation, and location of double bonds. Triglycerides are introduced as esters composed of glycerol and three fatty acid chains. Their physical properties depend on the fatty acid components, and they undergo hydrolysis, saponification, and hydrogenation reactions. The learning outcomes are to understand fatty acids and triglycerides, and distinguish between their physical and chemical properties.
This document summarizes key information about alkaloids. It discusses that alkaloids are nitrogen-containing organic compounds found in plants that have physiological effects. Common alkaloids like morphine, codeine, caffeine, and cocaine are mentioned. The characteristics, occurrence in plants, classification based on chemical structure, and examples of alkaloids used in modern medicine are described. The biosynthesis pathways of morphine and codeine from opium poppy are also summarized.
Advances in Ion Selective Electrodes(ISE) Nur Fatihah
The document summarizes a group project on advances in ion selective electrodes. It discusses the different types of ion selective electrodes including glass membrane electrodes, solid state electrodes, liquid membrane electrodes, and gas sensing electrodes. It describes the key parameters that characterize ion selective electrodes such as sensitivity, selectivity, detection limit, and response time. The document also discusses various applications of ion selective electrodes for online, on-site, and in vivo potentiometric measurements. Recent advances in the applications of ion selective electrodes in areas such as agriculture, pollution control, food quality control, medical diagnostics, and industrial production are highlighted.
Au nanospheres and nanorods for enzyme-free electrochemical biosensor applica...Nur Fatihah
1) The document describes the synthesis of gold nanospheres and nanorods with different morphologies for use in enzyme-free electrochemical biosensors.
2) The electrocatalytic properties and stability of biosensors using different gold nanocrystal shapes were investigated. Au nanocrystals were attached to screen-printed electrodes and used to detect hydrogen peroxide.
3) Results showed that the electrocatalytic properties and sensitivity of the biosensors depended on the morphology of the gold nanocrystals used. Biosensors using different shaped gold nanocrystals were stable for over 68 days.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
3. Mostly for qualitative analysis.
Absorption spectra is recorded as
transmittance.
Absorption in the infrared region arise from
molecular vibrational transitions
Absorption for every substance are at specific
wavelengths where IR spectra provides more
specific qualitative information.
IR spectra is called “fingerprints”
because no other chemical species will have
similar IR spectrum.
3
4. 4
The transmittance
spectra provide
better contrast
between intensities
of strong and weak
bands compared to
absorbance
spectra.
5. 5
Energy of IR photon insufficient to cause electronic
excitation but can cause vibrational excitation
7. Infrared (IR) spectroscopy deals with
the interaction of infrared radiation with
matter.
IR spectrum provides…..
Important information about its chemical
nature and molecular structure
IR applicability for…..
Analysis of organic materials
Polyatomic inorganic molecules
Organometallic compounds
7
8. IR region subdivided into 3 sub-regions
A.Near IR region (Nearest to the visible)
780 nm to 2.5 μm (12,800 to 4000 cm-1)
B. Mid IR region
2.5 to 50 μm (4000 – 200 cm-1)
C. Far IR region
50 to 1000 μm (200 – 10cm-1)
8
visible
infrared
microwave
NE
AR
MI
D
F
AR
9. 1. IR absorption only occurs when IR radiation
interacts with a molecule undergoing a
change in dipole moment as it vibrates
or rotates.
2. Infrared absorption only occurs when
the incoming IR photon has
sufficient energy for the
transition to the next allowed
vibrational state.
No absorption can occur if both rules
above are not met.
9
10. Absorption of IR radiation corresponds to energy
changes on the order of 8 to 40 kJ/mole.
Radiation in this energy range corresponds to
stretching and bending vibrational
frequencies of the bonds in most covalent
molecules.
In the absorption process, those frequencies of
IR radiation which match the natural
vibrational frequencies of the molecule are
absorbed.
The energy absorbed will increase the
amplitude of the vibrational motions of the
bonds in the molecule. 10
11. NOT ALL bonds in a molecule are capable
of absorbing IR energy. Only those bonds
that have change in dipole moment are
capable to absorb IR radiation.
The larger the dipole change, the
stronger the intensity of the band in
an IR spectrum.
11
12. is a measure of the extent to which a
separation exists between the centers
of positive and negative charge within
a molecule.
12
O
δ-
δ+H H
δ+
13. In heteronuclear diatomic molecule,
because of the difference in
electronegativities of the two atoms, one
atom acquires a small positive charge (δ+),
the other a negative charge (δ-).
This molecule is then said to have a dipole
moment whose magnitude, μ = qd
13
distance of separation of the charge
14. A. Compound absorb in IR region
Organic compounds, carbon
monoxide
B. Compounds DO NOT absorb in
IR region
O2, H2, N2, Cl2
14
15. A molecule can move via vibration, rotation
and translation (3 degree of freedom)
Polyatomic molecules containing N atoms
will have 3N degree of freedom
Molecules containing 3 atoms, two groups of
the triatomic molecules may be
distinguished; linear and non linear
Eg: CO2 (OCO) and H2O (HOH)
15
17. 17
Type of degree of freedom Linear Non
linear
Translational 3 3
Rotational 2 3
Vibrational 3N-5 3N-6
Total 3N 3N
18. Molecular vibration
divided into
back & forth
movement
involves change
in bond angles
stretching bending
symmetrical asymmetrical
scissoring
rocking twisting
wagging
in-plane
vibration
out of
plane
vibration
18
23. a drop of the pure (neat) liquid is squeezed
between two rock-salt plates to give a layer
that has thickness 0.01mm or less.
2 plates held together by capillary mounted
in the beam path.
23
24. What is meant by “neat” liquid?
Neat liquid is a pure liquid that do not contain
any solvent or water.
Neat liquid method is applied when the amount
of liquid is small or when a suitable solvent is
unavailable.
24
25. There are 2 ways to prepare solid
sample for IR spectroscopy.
1. Solid that is soluble in solvent . The
most commonly IR solvent is carbon
tetrachloride, CCl4.
2. Solid that is insoluble in CCl4 or any
other IR solvents can be prepared
either by KBr pellet or Mulls.
25
26. KBr PELLET
The finely ground solid sample is mixed with
potassium bromide (KBr). The mixture is
pressed under high pressure (10,000 –
15,000 psi) in special die to form a pellet.
KBr pellet then can be inserted into a holder
in the IR spectrometer.
26
27. MULLS
2-5 mg finely powdered sample is ground
(grind) together with the presence 1 or 2
drops of a heavy hydrocarbon oil called
Nujol to form a Mull.
Mull is then examined as a film between flat
salt plates.
Mulls method is applied when solid not
soluble in an IR transparent solvent
and solid is not convenient to be
pelleted with KBr.
27
28. What is Mull
A thick paste formed by grinding an
insoluble solid with an inert liquid and used
for studying spectra of the solid.
What is Nujol
A trade name for a heavy medicinal liquid
paraffin. Extensively used as a mulling agent
in spectroscopy.
28
32. Generate a beam with sufficient
power in the λ region of interest to
permit ready detection & measurement.
Provide continuous radiation which
made up of all λ’s with the region
(continuum source).
Provide stable output for the period
needed to measure both P0 and P.
32
35. Why FTIR is developed?
To overcome limitations
encountered with the
dispersive instruments.
Dispersive IR
spectrophotometer has slow
scanning speed due to
measurement of individual
molecules/atom.
It utilize the use of an
35
38. Interferometer
Special instrument which can read IR
frequencies simultaneously.
Faster method than dispersive instrument.
Interferograms are transformed into
frequency spectrums by using
mathematical technique called Fourier
Transformation.
38
FT
Calculations
interferograms IR spectrum
39. Majority of commercially available FTIR instruments
are based upon Michelson interferometer.
39
1
3
2
4
5
6
40. High sensitivity.
High resolution.
Quick data acquisition ( data for an
entire spectrum can be obtained in 1
s or less).
40
Advantages FTIR
42. IR spectrum is due to specific structural
features, a specific bond, within the
molecule, since the vibrational states
of individual bonds represent 1
vibrational transition.
From IR spectrum we could predict
the present of atoms or group of
atoms or functional groups such as the
present of an O-H bond or a C=O or an
aromatic ring.
42
44. Overtone and Combination Bands
Overtone bands – are multiplies of the
fundamental absorption frequency
First overtone band will appear at twice the
wavenumber of the fundamental.
Combination bands – arises when two
fundamental bands absorbing at v1 and v2
absorbs energy simultaneously. The resulting
band will appear at v1+v2 wavenumber
44
45. Example:
A molecule has strong fundamental bands as
follows:
C-H bending at 730cm-1
C-C stretching at 1400 cm-1
C-H stretching at 2950 cm-1.
Determine the wavenumbers of possible
combination bands and the first overtones.
45
46. Fermi resonance
-leads to two bands appearing close together
when one is expected
When an overtone or a combination band has
the same frequency as or similar frequency to
a fundamental, two bands appear, split at
either side of the expected value and are of
equal intensity – called as Fermi doublet
46
47. Coupling
Give rise to the complexity of the IR spectrum
Vibration in the skeleton of the molecules become
coupled
Bands can no longer be assigned to one bond.
Very common when adjacent bonds have similar
frequencies.
Commonly occurs between C-C, C-O and C-N
stretching, C-H rocking and C-H wagging
The vibrational mode is observed at different
frequencies
47
49. 49
How to analyze IR spectra
1. Begin by looking in the region from
4000-1300. Look at the C–H stretching
bands around 3000.
Indicates
Are any or all to the right
of 3000?
alkyl groups (present in
most organic molecules)
Are any or all to the left of
3000?
a C=C bond or aromatic
group in the molecule
50. 50
2. Look for a carbonyl in the region
1760-1690. If there is such a band:
Indicates
Is an O–H band also present?
a carboxylic acid
group
Is a C–O band also present? an ester
Is an aldehyde C–H band also
present?
an aldehyde
Is an N–H band also present? an amide
Are none of the above present? a ketone
(also check the exact position of the carbonyl band for clues as to
the type of carbonyl compound it is)
51. 51
3. Look for a broad O–H band in the
region 3500-3200 cm-1. If there is
such a band:
Indicates
Is an O–H band present? an alcohol or phenol
4. Look for a single or double sharp N–H
band in the region 3400-3250 cm-1. If
there is such a band:
Indicates
Are there two bands? a primary amine
Is there only one band? a secondary amine
52. 52
5. Other structural features to check for
Indicates
Are there C–O stretches?
an ether (or an ester if there
is a carbonyl band too)
Is there a C=C stretching
band?
an alkene
Are there aromatic
stretching bands?
an aromatic
Is there a C≡C band? an alkyne
Are there -NO2 bands? a nitro compound
53. How to analyze IR
spectra
If there is an absence of major functional
group bands in the region 4000-1300 cm-1
(other than C–H stretches), the compound is
probably a strict hydrocarbon.
Also check the region from 900-650 cm-1.
Aromatics, alkyl halides, carboxylic acids, amines,
and amides show moderate or strong absorption
bands (bending vibrations) in this region.
As a beginning student, you should not try to
assign or interpret every peak in the
spectrum. Concentrate on learning the
major bands and recognizing their
presence and absence in any given
spectrum. 53
57. CH Stretch for sp3 C-H around 3000 – 2840 cm-1.
CH2 Methylene groups have a characteristic bending absorption
at approximate 1465 cm-1
CH3 Methyl groups have a characteristic bending absorption at
approximate 1375 cm-1
CH2 The bending (rocking) motion associated with four or more
CH2 groups in an open chain occurs at about 720 cm-1 57
59. ALKENE
=C-H Stretch for sp2 C-H occurs at values greater than 3000 cm-1.
=C-H out-of-plane (oop) bending occurs in the range 1000 – 650 cm-1
C=C stretch occurs at 1660 – 1600 cm-1;
often conjugation moves C=C stretch to lower frequencies
and increases the intensity.
59
61. CH
C C
ALKYNE
Stretch for sp C - H occurs near 3300 cm-1.
Stretch occurs near 2150 cm-1; conjugation moves stretch to
lower frequency.
61
62. AROMATIC
RINGS
C H Stretch for sp2 C-H occurs at values greater than 3000 cm-1.
C C Ring stretch absorptions occur in pairs at 1600 cm-1 and
1475 cm-1.
C H Bending occurs at 900 - 690cm-1.
62
64. C-H Bending ( for Aromatic
Ring)
The out-of-plane (oop) C-H bending is useful in order to assign the
positions of substituents on the aromatic ring.
Monosubstituted rings
•this substitution pattern always gives a strong absorption near 690
cm-1. If this band is absent, no monosubstituted ring is present. A
second strong band usually appears near 750 cm-1.
Ortho-Disubstituted rings
•one strong band near 750 cm-1.
Meta- Disubstituted rings
•gives one absorption band near 690 cm-1 plus one near 780 cm-1. A
third band of medium intensity is often found near 880 cm-1.
Para- Disubstituted rings
- one strong band appears in the region from 800 to 850 cm-1. 64
66. Meta- Disubstituted rings
- gives one absorption band near 690 cm-1 plus one near 780
cm-1. A third band of medium intensity is often found near 880
cm-1.
C H
66
68. ALCOHOL
CH3
H3C C
OH
CH3
H
Primary alcohol 10
H
Secondary alcohol 20
Tertiary alcohol 30
C C OH
H
H
H
H
C C C
H
H
OH
H
H
H
H
68
69. ALCOHOL
O-H The hydrogen-bonded O-H band is a broad peak at 3400 – 3300 cm-1.
This band is usually the only one present in an alcohol that
has not been dissolved in a solvent (neat liquid).
C-O-H Bending appears as a broad and weak peak at 1440 – 1220 cm-1
often obscured by the CH3 bendings.
C-O Stretching vibration usually occurs in the range 1260 – 1000 cm-1.
This band can be used to assign a primary, secondary or tertiary
structure to an alcohol.
69
73. ETHER
R O R'
C-O The most prominent band is that due to C-O stretch,
1300 – 1000 cm-1.
Absence of C=O and O-H is required to ensure that C-O stretch
is not due to an ester or an alcohol.
Phenyl alkyl ethers give two strong bands at about
1250 – 1040 cm-1,
while aliphatic ethers give one strong band at about 1120 cm-1.
73
75. CARBONYL
COMPOUNDS
cm-1
1810 1800 1760 1735 1725 1715 1710 1690
Anhydride Acid Chloride Anhydride Ester Aldehyde Ketone Carboxylic acid
Amide
(band 1) (band 2)
Normal base values for the C=O stretching vibrations for
carbonyl groups.
75
76. ALDEHYDE
R C
O
H
R C
O
H
Ar C
O
H
C=O stretch appear in range 1740-1725 cm-1 for
normal aliphatic aldehydes
Conjugation of C=O with phenyl; 1700 – 1660 cm-1 for C=O
and 1600 – 1450 cm-1 for ring (C=C)
C-H Stretch, aldehyde hydrogen (---CHO), consists of weak
bands, one at 2860 - 2800 cm-1 and
the other at 2760 – 2700 cm-1.
76
78. KETONE
R C R'
O
R C R'
O
Ar C R'
O
C=O stretch appear in range 1720-1708
cm-1 for normal aliphatic ketones
Conjugation of C=O with phenyl at 1700 –
1680 cm-1 for C=O
and 1600 – 1450 cm-1 for ring (C=C)
78
82. ESTER
R C
O
O R
R C
O
O R
Ar C
O
O R
C=O stretch appear in range 1750-1735 cm-1 for
normal aliphatic esters
Conjugation of C=O with phenyl; 1740 – 1715 cm-1
for C=O
and 1600 – 1450 cm-1 for ring (C=C)
C – O Stretch in two or more bands, one stronger and
one broader than the other,
occurs in the range 1300 – 1000 cm-1
82
86. 86
O
C Cl
R
C O
C Cl
Stretch appear in range 1810 -1775 cm-1 in
conjugated chlorides. Conjugation lowers the
frequency to 1780 – 1760 cm-1
Stretch occurs in the range 730 -550 cm-1
Acid chloride show a very strong band for the C=O group.
87. 87
O O
R R
C O C
C O Stretch always has two bands, 1830 -1800 cm-1 and 1775 –
1740 cm-1, with variable relative intensity.
Conjugation moves the absorption to a lower frequency.
Ring strain (cyclic anhydride) moves absorptions to a
higher frequency.
C O Stretch (multiple bands) occurs in the range 1300 -900 cm-1
88. R N
H
H
R
HN
R
R N R
R
88
Primary amine, 10
Secondary amine , 20
Tertiary amine, 30
89. 89
Stretching occurs in the range 3500 – 3300 cm-1.
Primary amines have two bands.
Secondary amines have one band, a vanishingly
weak one for aliphatic compounds and a stronger one
for aromatic secondary amines.
Tertiary amines have no N – H stretch.
Out-of-plane bending absorption can sometimes be
observed near 800 cm-1
Stretch occurs in the range 1350 – 1000 cm-1
N – H
Bending in primary amines results in a broad band in the
range 1640 – 1560 cm-1.
Secondary amines absorb near 1500 cm-1
N – H
N – H
C – N