This document discusses factors that affect fluorescence and phosphorescence. It defines fluorescence and phosphorescence as types of molecular luminescence that are excited by photon absorption. The main difference is that fluorescence involves no change in electron spin, while phosphorescence does involve a change. Several factors can influence emission, including molecular structure and rigidity, temperature, solvent properties, pH, dissolved oxygen, concentration, and the presence of heavy atoms. More rigid and planar structures favor fluorescence and phosphorescence. Higher temperatures, viscosities, and oxygen levels decrease emission, while appropriate solvent polarity and pH can increase it.
In this slides contains principle and instrumentation of Differential Scanning Calorimeter (DSC).
Presented by: N Poojitha. (Department of pharmaceutics),
RIPER, anantapur.
Spin-spin coupling occurs between neighboring NMR-active nuclei and causes splitting of NMR spectra. The splitting pattern is related to the number of equivalent hydrogen atoms near the nuclei. The distance between peaks in a split signal is the coupling constant (J) measured in Hertz. Factors like number of bonds between nuclei, bond angles, and molecular rigidity can affect the coupling constant value. Complex coupling results when a set of hydrogen is coupled to two or more nonequivalent neighbors, producing more complex splitting patterns.
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.
This document discusses double resonance in nuclear magnetic resonance (NMR) spectroscopy. It explains spin decoupling techniques that are used to simplify complex NMR spectra. By irradiating coupled protons, decoupling can eliminate splitting of signals and cause multiplets to collapse into doublets or singlets. This produces easier to interpret spectra. Decoupling is demonstrated on an ethanol sample, where exchanging hydrogens for deuterium causes signals to disappear. Irradiating methyl hydrogens in a molecule can also simplify signals by removing coupling to adjacent protons. Decoupling enhances spectral signals and allows clearer distinction between them.
FT-IR spectroscopy Instrumentation and Application, By- Anubhav singh, M.pharmAnubhav Singh
This document discusses instrumentation and applications of Fourier transform infrared (FTIR) spectroscopy. It begins by explaining the basic principles of FTIR spectroscopy, how it works, and its advantages over dispersive infrared spectroscopy. It then describes various applications of FTIR spectroscopy like polymer processing, plasma etching, identification of materials, and analysis of formulations. Specific examples discussed include drying and curing polymers, monitoring plasma etching, identifying contamination, and distinguishing different functional groups in molecules. The document concludes by noting the advantages, limitations, and comparison of FTIR spectroscopy to dispersive infrared spectroscopy.
Spin-lattice & spin-spin relaxation, signal splitting & signal multiplicity concepts briefly explained relevant to Nuclear Magnetic Resonance Spectroscopy.
In this slides contains principle and instrumentation of Differential Scanning Calorimeter (DSC).
Presented by: N Poojitha. (Department of pharmaceutics),
RIPER, anantapur.
Spin-spin coupling occurs between neighboring NMR-active nuclei and causes splitting of NMR spectra. The splitting pattern is related to the number of equivalent hydrogen atoms near the nuclei. The distance between peaks in a split signal is the coupling constant (J) measured in Hertz. Factors like number of bonds between nuclei, bond angles, and molecular rigidity can affect the coupling constant value. Complex coupling results when a set of hydrogen is coupled to two or more nonequivalent neighbors, producing more complex splitting patterns.
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.
This document discusses double resonance in nuclear magnetic resonance (NMR) spectroscopy. It explains spin decoupling techniques that are used to simplify complex NMR spectra. By irradiating coupled protons, decoupling can eliminate splitting of signals and cause multiplets to collapse into doublets or singlets. This produces easier to interpret spectra. Decoupling is demonstrated on an ethanol sample, where exchanging hydrogens for deuterium causes signals to disappear. Irradiating methyl hydrogens in a molecule can also simplify signals by removing coupling to adjacent protons. Decoupling enhances spectral signals and allows clearer distinction between them.
FT-IR spectroscopy Instrumentation and Application, By- Anubhav singh, M.pharmAnubhav Singh
This document discusses instrumentation and applications of Fourier transform infrared (FTIR) spectroscopy. It begins by explaining the basic principles of FTIR spectroscopy, how it works, and its advantages over dispersive infrared spectroscopy. It then describes various applications of FTIR spectroscopy like polymer processing, plasma etching, identification of materials, and analysis of formulations. Specific examples discussed include drying and curing polymers, monitoring plasma etching, identifying contamination, and distinguishing different functional groups in molecules. The document concludes by noting the advantages, limitations, and comparison of FTIR spectroscopy to dispersive infrared spectroscopy.
Spin-lattice & spin-spin relaxation, signal splitting & signal multiplicity concepts briefly explained relevant to Nuclear Magnetic Resonance Spectroscopy.
This presentation include the detailed explanation of various parts of a UV-Visible spectrophotometer and two types of UV-Visible spectrophotometers-Single beam and Doube beam. It also include the comparison between single beam and double beam spectrophotometers.
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.
Solvents and solvent effect in UV - Vis Spectroscopy, By Dr. Umesh Kumar sh...Dr. UMESH KUMAR SHARMA
This document discusses solvent effects on UV-visible spectroscopy. It begins by explaining that UV spectra are usually measured in dilute solutions using solvents that are transparent in the wavelength range and do not interact strongly with the solute. Common solvents mentioned are ethanol, hexane, and water. The document then discusses various solvent effects including bathochromic shifts, hypsochromic shifts, hyperchromic shifts, and hypochromic shifts. It provides examples of how solvents can alter absorption wavelengths and intensities. The document concludes by mentioning several reference texts on this topic.
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.
MASS SPECTROSCOPY ( Molecular ion, Base peak, Isotopic abundance, Metastable ...Sachin Kale
CONTENT:
Molecular Ion Peak
Significance of Molecular ion & Graphically Method
Base Peak
Isotopic Abundance
Metastable Ion
Significance of Metastable ion
Nitrogen Rule & graphs
Formulation of Rule
UV-visible spectroscopy is a technique that uses light in the visible and adjacent ranges. It works by measuring how much light is absorbed by a sample at each wavelength. There are several types of electronic transitions that can occur when molecules absorb this light. The amount of light absorbed follows Beer's law and is proportional to the concentration and path length of the sample. A UV-visible spectrophotometer consists of a light source, monochromator, sample holder, detector, and recording device. This technique has many applications including detection of impurities, structure elucidation, and quantitative analysis in pharmaceutical analysis.
This document discusses the instrumentation of UV spectrophotometry. It describes the key components which include sources of UV radiation like hydrogen discharge lamps, xenon discharge lamps, and mercury arc lamps. It also discusses monochromators like gratings to produce monochromatic light, and sample holders/cuvettes to hold liquid samples. Common detectors mentioned are barrier layer cells, phototubes, and photomultiplier tubes. Finally, it explains the basic setup of single beam and double beam UV spectrophotometers used for analysis.
Proton nuclear magnetic resonance spectroscopy (PNMR) is described. PNMR involves absorbing radiofrequency radiation by proton nuclei in a strong magnetic field. It is used to determine the type and number of hydrogen atoms in a molecule. The chemical shift range is 0-14 ppm and splitting is seen between non-equivalent protons. PNMR provides information on molecular structure and hydrogen bonding. Applications include structure elucidation of organic compounds, polymers, and biomolecules. Differences between PNMR and carbon-13 NMR are also outlined.
INSTRUMENTAL METHODS OF ANALYSIS, B.PHARM 7TH SEM. AND FOR BSC,MSC CHEMISTRY. This is Geeta prasad kashyap (Asst. Professor), SVITS, Bilaspur (C.G) 495001
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 provides an overview of UV-Visible spectroscopy. It discusses how UV radiation causes electronic transitions in molecules, which can be observed via absorption spectroscopy. The instrumentation used includes sources of UV and visible light, a monochromator to select wavelengths, and a detector. Samples are dissolved and placed in transparent cuvettes for analysis. Spectra are recorded as absorbances and show absorption bands corresponding to electronic transitions. UV-Vis is useful for structure elucidation and quantitative analysis.
Factors affecting IR absorption frequency Vrushali Tambe
1. Many factors affect the absorption frequency in IR spectroscopy, including reduced mass, bond strength, hydrogen bonding, electronic effects, and molecular structure.
2. Coupling between vibrations and Fermi resonance can cause frequency shifts and intensity changes. Hydrogen bonding causes broad bands while strong bonds absorb at higher frequencies.
3. Electronic effects like induction, mesomerism, and conjugation influence frequency by altering bond strength. Ring size, hybridization, and physical state also impact the absorption frequency.
This document provides an overview of NMR spectroscopy. It begins by explaining the fundamental principles, including that NMR spectroscopy detects the absorption of radio waves by atomic nuclei placed in a magnetic field. It then discusses various aspects of interpreting NMR spectra such as chemical shifts, spin-spin coupling and integrals. The document also covers NMR techniques including Fourier transformation, 2D NMR, and relaxation processes. In summary, the document serves as an introduction to NMR spectroscopy and the principles behind analyzing NMR spectral data.
Nuclear Magnetic Double Resonance (Decoupling).pptxRushikeshTidake
This document discusses nuclear magnetic double resonance (decoupling) in NMR spectroscopy. It explains that decoupling involves irradiating a proton to prevent coupling with neighboring protons, simplifying complex spectra. Decoupling causes multiplets to collapse into doublets or singlets, making spectra easier to interpret. It provides an example using ethanol, noting how decoupling removes signals by exchanging protons for deuterium. The document also discusses how decoupling averages spins to zero to remove spin-spin interactions and simplify coupled signals.
Introduction and Principle of IR spectroscopyRajaram Kshetri
This document provides an introduction to infrared (IR) spectrophotometry. It discusses how IR spectroscopy analyzes molecular vibrations when molecules absorb IR radiation that matches their natural vibrational frequencies. The document outlines the principle of IR spectroscopy and describes the different types of molecular vibrations observed in IR spectra, including stretching and bending vibrations. It also discusses the criteria for a molecule to absorb IR radiation, such as having a change in dipole moment when vibrations occur.
The document discusses atomic absorption spectroscopy. It begins with an introduction describing how atomic absorption spectroscopy measures the concentration of an element by measuring the amount of light absorbed at a characteristic wavelength when it passes through atoms of that element. It then describes the principle, instrumentation, applications, and sources of interference in atomic absorption spectroscopy. The key sources of interference discussed are non-spectral interferences such as matrix, chemical, and ionization interferences and spectral interferences such as background absorption.
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.
this ppt contain all basic information related to the mass spectrometry like introduction, principle of MS, type of ions, fragmentation processes eg. mcLafferty rearrangement, alpha clevage, sigma bond clevage, retro-diels-alder reaction
Fluorimetry is a sensitive analytical technique that uses fluorescence spectroscopy to measure the intensity of fluorescence emitted by a sample. A fluorimeter/spectrofluorimeter uses a light source like a mercury lamp to excite fluorescence in a sample, filters/monochromators to select excitation and emission wavelengths, a sample holder, and a photomultiplier tube detector to measure the low-intensity fluorescent signal. Factors like molecular structure, solvent, temperature, and presence of quenchers influence fluorescence intensity and can provide information about samples. Fluorimetry is more sensitive and selective than absorption spectroscopy.
This document discusses fluorescence, phosphorescence, and chemiluminescence. It describes how fluorescence and phosphorescence involve the absorption and emission of photons during molecular excitation, while chemiluminescence occurs through chemical reactions without photon absorption. Factors that influence fluorescence and phosphorescence such as temperature, pH, solvent, and molecular structure are also examined. Finally, the basic instrumentation for measuring fluorescence and phosphorescence is outlined, including the use of rotating shutters for phosphorescence measurements at cryogenic temperatures.
This presentation include the detailed explanation of various parts of a UV-Visible spectrophotometer and two types of UV-Visible spectrophotometers-Single beam and Doube beam. It also include the comparison between single beam and double beam spectrophotometers.
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.
Solvents and solvent effect in UV - Vis Spectroscopy, By Dr. Umesh Kumar sh...Dr. UMESH KUMAR SHARMA
This document discusses solvent effects on UV-visible spectroscopy. It begins by explaining that UV spectra are usually measured in dilute solutions using solvents that are transparent in the wavelength range and do not interact strongly with the solute. Common solvents mentioned are ethanol, hexane, and water. The document then discusses various solvent effects including bathochromic shifts, hypsochromic shifts, hyperchromic shifts, and hypochromic shifts. It provides examples of how solvents can alter absorption wavelengths and intensities. The document concludes by mentioning several reference texts on this topic.
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.
MASS SPECTROSCOPY ( Molecular ion, Base peak, Isotopic abundance, Metastable ...Sachin Kale
CONTENT:
Molecular Ion Peak
Significance of Molecular ion & Graphically Method
Base Peak
Isotopic Abundance
Metastable Ion
Significance of Metastable ion
Nitrogen Rule & graphs
Formulation of Rule
UV-visible spectroscopy is a technique that uses light in the visible and adjacent ranges. It works by measuring how much light is absorbed by a sample at each wavelength. There are several types of electronic transitions that can occur when molecules absorb this light. The amount of light absorbed follows Beer's law and is proportional to the concentration and path length of the sample. A UV-visible spectrophotometer consists of a light source, monochromator, sample holder, detector, and recording device. This technique has many applications including detection of impurities, structure elucidation, and quantitative analysis in pharmaceutical analysis.
This document discusses the instrumentation of UV spectrophotometry. It describes the key components which include sources of UV radiation like hydrogen discharge lamps, xenon discharge lamps, and mercury arc lamps. It also discusses monochromators like gratings to produce monochromatic light, and sample holders/cuvettes to hold liquid samples. Common detectors mentioned are barrier layer cells, phototubes, and photomultiplier tubes. Finally, it explains the basic setup of single beam and double beam UV spectrophotometers used for analysis.
Proton nuclear magnetic resonance spectroscopy (PNMR) is described. PNMR involves absorbing radiofrequency radiation by proton nuclei in a strong magnetic field. It is used to determine the type and number of hydrogen atoms in a molecule. The chemical shift range is 0-14 ppm and splitting is seen between non-equivalent protons. PNMR provides information on molecular structure and hydrogen bonding. Applications include structure elucidation of organic compounds, polymers, and biomolecules. Differences between PNMR and carbon-13 NMR are also outlined.
INSTRUMENTAL METHODS OF ANALYSIS, B.PHARM 7TH SEM. AND FOR BSC,MSC CHEMISTRY. This is Geeta prasad kashyap (Asst. Professor), SVITS, Bilaspur (C.G) 495001
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 provides an overview of UV-Visible spectroscopy. It discusses how UV radiation causes electronic transitions in molecules, which can be observed via absorption spectroscopy. The instrumentation used includes sources of UV and visible light, a monochromator to select wavelengths, and a detector. Samples are dissolved and placed in transparent cuvettes for analysis. Spectra are recorded as absorbances and show absorption bands corresponding to electronic transitions. UV-Vis is useful for structure elucidation and quantitative analysis.
Factors affecting IR absorption frequency Vrushali Tambe
1. Many factors affect the absorption frequency in IR spectroscopy, including reduced mass, bond strength, hydrogen bonding, electronic effects, and molecular structure.
2. Coupling between vibrations and Fermi resonance can cause frequency shifts and intensity changes. Hydrogen bonding causes broad bands while strong bonds absorb at higher frequencies.
3. Electronic effects like induction, mesomerism, and conjugation influence frequency by altering bond strength. Ring size, hybridization, and physical state also impact the absorption frequency.
This document provides an overview of NMR spectroscopy. It begins by explaining the fundamental principles, including that NMR spectroscopy detects the absorption of radio waves by atomic nuclei placed in a magnetic field. It then discusses various aspects of interpreting NMR spectra such as chemical shifts, spin-spin coupling and integrals. The document also covers NMR techniques including Fourier transformation, 2D NMR, and relaxation processes. In summary, the document serves as an introduction to NMR spectroscopy and the principles behind analyzing NMR spectral data.
Nuclear Magnetic Double Resonance (Decoupling).pptxRushikeshTidake
This document discusses nuclear magnetic double resonance (decoupling) in NMR spectroscopy. It explains that decoupling involves irradiating a proton to prevent coupling with neighboring protons, simplifying complex spectra. Decoupling causes multiplets to collapse into doublets or singlets, making spectra easier to interpret. It provides an example using ethanol, noting how decoupling removes signals by exchanging protons for deuterium. The document also discusses how decoupling averages spins to zero to remove spin-spin interactions and simplify coupled signals.
Introduction and Principle of IR spectroscopyRajaram Kshetri
This document provides an introduction to infrared (IR) spectrophotometry. It discusses how IR spectroscopy analyzes molecular vibrations when molecules absorb IR radiation that matches their natural vibrational frequencies. The document outlines the principle of IR spectroscopy and describes the different types of molecular vibrations observed in IR spectra, including stretching and bending vibrations. It also discusses the criteria for a molecule to absorb IR radiation, such as having a change in dipole moment when vibrations occur.
The document discusses atomic absorption spectroscopy. It begins with an introduction describing how atomic absorption spectroscopy measures the concentration of an element by measuring the amount of light absorbed at a characteristic wavelength when it passes through atoms of that element. It then describes the principle, instrumentation, applications, and sources of interference in atomic absorption spectroscopy. The key sources of interference discussed are non-spectral interferences such as matrix, chemical, and ionization interferences and spectral interferences such as background absorption.
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.
this ppt contain all basic information related to the mass spectrometry like introduction, principle of MS, type of ions, fragmentation processes eg. mcLafferty rearrangement, alpha clevage, sigma bond clevage, retro-diels-alder reaction
Fluorimetry is a sensitive analytical technique that uses fluorescence spectroscopy to measure the intensity of fluorescence emitted by a sample. A fluorimeter/spectrofluorimeter uses a light source like a mercury lamp to excite fluorescence in a sample, filters/monochromators to select excitation and emission wavelengths, a sample holder, and a photomultiplier tube detector to measure the low-intensity fluorescent signal. Factors like molecular structure, solvent, temperature, and presence of quenchers influence fluorescence intensity and can provide information about samples. Fluorimetry is more sensitive and selective than absorption spectroscopy.
This document discusses fluorescence, phosphorescence, and chemiluminescence. It describes how fluorescence and phosphorescence involve the absorption and emission of photons during molecular excitation, while chemiluminescence occurs through chemical reactions without photon absorption. Factors that influence fluorescence and phosphorescence such as temperature, pH, solvent, and molecular structure are also examined. Finally, the basic instrumentation for measuring fluorescence and phosphorescence is outlined, including the use of rotating shutters for phosphorescence measurements at cryogenic temperatures.
This document discusses factors that affect fluorimetry and quenching. It lists several factors that can influence fluorescence, including the nature of molecules, substituents, concentration, adsorption, light, oxygen, pH, temperature, and viscosity. It also describes different types of quenching such as self-quenching, chemical quenching, static quenching, and collisional quenching. Chemical quenching can occur due to changes in pH, presence of oxygen, or heavy metals. Static quenching involves complex formation between the fluorophore and quencher. Collisional quenching occurs through interactions between an excited fluorophore and quencher molecule.
Spectrofluorimetry or fluorimetry (www.Redicals.com)Goa App
The term fluorescence comes from the mineral fluorspar (calcium fluoride) when Sir George G. Stokes observed in 1852 that fluorspar would give off visible light (fluoresce) when exposed to electromagnetic radiation in the ultraviolet wavelength.
Spectrofluorimetry uses fluorescence to analyze samples. It involves exciting a sample with light and measuring the wavelength and intensity of any light emitted. Key aspects covered in the document include:
- The history of fluorescence and different types of luminescence
- How spectrofluorometers work using light sources, filters/monochromators, sample cells, and detectors
- Factors that influence fluorescence intensity
- Applications of spectrofluorometry in environmental and chemical analysis
Fluorescence spectroscopy involves exciting a chemical substance with UV or visible light, causing it to emit light at a longer wavelength. This phenomenon is called luminescence. Depending on the lifetime of the excited state, luminescence is categorized into fluorescence (10-8 to 10-4 seconds) or phosphorescence (10-4 to 10 seconds). Fluorometry is a sensitive analytical technique used in various fields like biochemistry and environmental science to study molecular interactions and assay fluorescent compounds like drugs. It provides high selectivity for trace analysis of substances in biological samples.
This document discusses fluorescence spectroscopy and its applications in pharmacy. It begins with definitions of fluorescence, phosphorescence, and chemiluminescence. It describes how fluorescent substances emit light when exposed to radiation and discusses factors that affect fluorescence like molecular structure, substituents, concentration, oxygen, pH, and temperature. The principles of fluorescence are explained using Jablonski diagrams. Instrumentation for fluorescence spectroscopy including light sources, filters, sample cells, and detectors are outlined. Finally, applications of fluorescence spectroscopy in inorganic analysis, organic analysis, liquid chromatography, and determination of vitamins and drugs are described.
This document provides an overview of fluorometry, including basic concepts, instrumentation, and applications. It discusses how fluorescence occurs when a molecule absorbs light at one wavelength and reemits light at a longer wavelength. Factors that affect fluorescence such as temperature, pH, and dissolved oxygen are also covered. The relationship between fluorescence intensity and concentration is explained. Additionally, the document defines fluorescence polarization and describes various types of quenching including self-quenching, chemical quenching, and collisional quenching.
1) Chemical shift is defined as the shifts in NMR signals due to shielding or deshielding of protons by electrons in different chemical environments. (2) Factors that affect chemical shift include electronegativity, solvent effects, hydrogen bonding, and anisotropic effects. (3) Lanthanide shift reagents interact with functional groups, simplifying NMR spectra through induced chemical shifts.
Spectrofluorimetry is a technique that uses fluorescence to measure analytes. It involves exciting a sample with light of a specific wavelength, which causes the sample to emit light of a longer wavelength. The amount of emitted light is proportional to the analyte concentration. Factors like pH, temperature, and solvent can affect fluorescence intensity. The main components of a spectrofluorimeter are a light source, monochromator, sample cell, and light detector. Applications include determining inorganic substances, pharmaceutical analysis, and liquid chromatography.
This document discusses molecular fluorescence and phosphorescence spectroscopy. It provides details on:
- The processes of fluorescence, where emission occurs from an excited singlet state, and phosphorescence, where emission occurs from an excited triplet state.
- Factors that influence fluorescence and phosphorescence intensities like quantum yield, transition types (π->π* vs π->n), molecular structure, and competing deactivation processes.
- How excitation and emission spectra are obtained and related to the energy of electronic state transitions.
- Applications of photoluminescence spectroscopy like determining material band gaps and quality.
Fluorescence spectroscopy is a technique that uses fluorescence from molecules to analyze samples. Certain molecules emit light at longer wavelengths after absorbing ultraviolet or visible light (fluorescence). This technique is highly sensitive and can detect fluorescent compounds even when present at low concentrations. It has various applications like determining drugs in formulations, studying drug-protein binding, and bioanalysis. Factors like temperature, pH, concentration, and molecular structure can influence fluorescence intensity. Fluorometers contain a light source, wavelength selection devices, and photodetectors to measure fluorescence from samples.
This document discusses factors that affect fluorescence intensity. It explains that fluorescence intensity is directly proportional to the rigidity of a structure and inversely proportional to temperature. Other factors that can decrease fluorescence intensity include oxygen, which can oxidize fluorescent substances, as well as electron withdrawing substituent groups. Fluorescence intensity is directly proportional to concentration at low concentrations but does not obey linearity at high concentrations. The presence of other non-fluorescent solutes can also impact intensity through inner filter effects. In conclusion, several physicochemical factors influence fluorescence intensity measurements.
Heavy Atom Quenching is a process inducing radiationless intersystem crossing converting molecules from a vibrationally active S1 state into an iso energetic triplet state T1.
Heavy atoms or Atoms of high nuclear charge, either as substituents of fluorescent compounds or part of solvent, assumed to quench fluorescence by perturbation of fluorescencing state S1 via spin orbit coupling and hence deactivation into induced triplet state.
A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. These parameters are used to identify the presence and the number of specific molecules in a medium.
1. Fluorimetry is the measurement of fluorescence intensity using a fluorimeter or spectrofluorimeter. It involves exciting a molecule with specific wavelengths of light which causes electrons to get promoted to excited states, then relax emitting light of longer wavelengths.
2. Key components of fluorimeters include light sources like mercury lamps, filters to select wavelengths, sample cells, and detectors like photomultiplier tubes. Spectrofluorimeters use monochromators instead of filters to isolate wavelengths.
3. Fluorescence can be quenched by factors like oxygen, pH, temperature. Applications include determining inorganic/organic substances, proteins, pigments in nanogram amounts.
This document provides an overview of spectrofluorimetry and fluorescence. It begins by explaining the principles behind fluorescence - how absorption of UV or visible light causes electrons to transition to an excited state and then emit light as they fall back down. It then discusses fluorescence and fluorimetry in more detail. The rest of the document covers the Jablonski diagram, factors that affect fluorescence, types of quenching, instrumentation used including light sources, filters, sample cells and detectors, and applications of fluorescence including pharmaceutical analysis.
spectrofluorometer is the instrument for recording fluorescence emission and absorption spectra When a beam of light is incident on certain substances they emit visible light or radiations. This is known as fluorescence. Fluorescence starts immediately after the absorption of light and stops as soon as the incident light is cut off. The substances showing this phenomenon are known as flourescent substances.
the presentation gives knowledge about principle or fluorometry, factors that affect fluorescence including quenching instruments used in fluorometry, and the applications of fluorometry. added references in the end for more knowledge.
Similar to factors affecting fluorescence & phosphorescence (20)
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
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.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
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.
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.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
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.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
5. List Of Contents
• Introduction Of Fluorescence and Phosphorescence
• Possible de-excitation pathways of excited molecules
• Jablonski energy-level Diagrams
• Comparison between Fluorescence and Phosphorescence
• Variables that Affect Fluorescence
• FactorsThat Affect Photoluminescence
• References
5
7. Fluorescence and Phosphorescence
• Fluorescence and phosphorescence are types of molecular
luminescence methods.
• A molecule of analyte absorbs a photon and excites a species.
• The emission spectrum can provide qualitative and quantitative
analysis.
• The term fluorescence and phosphorescence are usually referred as
photoluminescence because both are alike in excitation brought by
absorption of a photon, only differ in relaxation process.
7
10. Fluorescence Phosphorescence
• short-lived
• Need source for excitation
• No change in electron spin
• Endure for several seconds
• Need source for excitation
• Change in electron spin
10
12. Variables that Affect Fluorescence
• Structure and structural Rigidity
• Temperature – increased temperature, decreased quantum yield
• SolventViscosity – lower viscosity, lower quantum yield
• Fluorescence usually pH-dependent
• Dissolved oxygen reduces emission intensity
• Concentration: Self-quenching due to collisions of excited molecules.
Self-absorbance when fluorescence emission and absorbance
wavelengths overlap.
12
13. Fluorescence And Structure
• As indicated earlier, best luminescence is observed for molecules with π bonds
and preferably those having aromatic rings due to presence of low energy 𝛑 − 𝝅*.
• Compounds containing aliphatic and alicyclic carbonyl structures or highly
conjugated double-bond structures may also exhibit fluorescence.
• Electron withdrawing groups like –COOH ,-N=N-, NO2 and halides decrease
fluorescence.
• Electron donating groups like –OH, and –NH2 are strongly fluorescence.
• Most unsubstituted aromatic hydrocarbons fluoresce in solution; the quantum
efficiency usually increases with the number of rings and their degree of
condensation.
• However, some heterocyclic aromatic rings do not show fluorescence.
• These include pyridine, furan, pyrrole, and thiophene 13
14. Cont.…
The lack of fluorescence in such molecules is largely believed to be due to:
• With nitrogen heterocyclic, the lowest-energy electronic transition is believed to involve n to 𝜋*
system that rapidly converts to the triplet state and prevents fluorescence.
• However, fusion of a phenyl ring to any of the molecules increase the possibility of the 𝝅 − 𝝅 ∗
transitions and thus increase the fluorescence quantum efficiency.
• Fusion of benzene rings to a heterocyclic nucleus, however, results in an increase in the molar
absorptivity of the absorption peak. The lifetime of an excited state is shorter in such structures;
fluorescence is thus observed for compounds such as quinoline, isoquinoline, and indole.
• Substitution of a carboxylic acid or carbonyl group on an aromatic ring generally inhibits
fluorescence.
• In these compounds, the energy of the n to 𝜋* transition is less than that of the 𝜋 to 𝜋* transition;
as pointed out earlier, the fluorescence yield from the former type of system is ordinarily low
14
15. Heavy Atom Effect
• Halogens constituents cause a decrease in fluorescence and the decrease
increases with atomic number of halogens.
• The decrease in fluorescence with increasing atomic number of the halogen is
thought to be due in part to the heavy atom effect, which increases the
probability for intersystem crossing to the triplet state.
• Spin/orbital interactions become large in the presence of heavy atoms and a
change in spin is thus more favorable.
• Predissociation is thought to play an important role in iodobenzene (for example)
that has easily ruptured bonds that can absorb the excitation energy following
internal conversion.
• Substitution of a carboxylic acid or carbonyl group on an aromatic ring generally
inhibits fluorescence. In these compounds, the energy of the n-𝝅* transition is
less than that of the 𝝅 − 𝝅 * transition.
15
16. Cont.…
• The electromagnetic fields that are associated with relatively heavy atoms affect electron
spins within a molecule more than the fields associated with lighter atoms.
• The addition of a relatively heavy atom to a molecule causes excited singlet and triplet
electrons to become more energetically similar. That reduces the energetic difference
between the singlet and triplet states and increases the probability of intersystem
crossing and of phosphorescence. The probability of fluorescence is simultaneously
reduced.
• The increased phosphorescence and decreased fluorescence with the addition of a heavy
atom is the heavy-atom effect.
• If the heavy atom is a substituent on the luminescent molecule, it is the internal heavy-
atom effect. The external heavy-atom effect occurs when the heavy atom is part of the
solution (usually the solvent) in which the luminescent compound is dissolved rather than
directly attached to the luminescent molecule.
• The effect that the halides have upon a luminescent molecule is an example of the
internal heavy-atom effect.
16
18. Photoluminescence is favored when the absorption is efficient (high absorptivities).
• Fluorescence is favored when
1. The energetic difference between the excited singlet and triplet states is relatively
large
2. The energetic difference between the first excited singlet state and the ground state
is sufficiently large to prevent appreciable relaxation to the ground state by
radiationless processes.
• Phosphorescence is favored when
1. The energetic difference between the first excited singlet state and the first excited
triplet state is relatively small
2. The probability of a radiationless transition from the triplet state to the ground state
is low.
• Any physical or chemical factor that can affect any of the transitions can affect the
photoluminescence.
• These factors include: structural rigidity, temp., solvent, pH, dissolved oxygen.
18
19. Effects of Structural Rigidity
• The nature of the chemical structure of a molecule in terms of flexibility and
rigidity is of major influence on the Photoluminescence signal.
• High degree of flexibility will trend to decrease the fluorescence(due to collision)
• More rigid structure have lower collision, thus have more fluorescence potential.
• Photoluminescent compounds are those compounds in which the energetic levels
within the compounds favor de-excitation by emission of UV-visible radiation
rather than by loss of rotational or vibrational energy
• Fluorescing and phosphorescing compounds usually have a rigid planar structure
• The quantum efficiencies for fluorene and biphenyl are nearly 1.0 and 0.2,
respectively, under similar conditions CH2 causes more rigidity
19
20. Cont.…
• The rigidity of the molecule prevents loss of energy through rotational and vibrational
energetic level changes.
• Any subsistent on a luminescent molecule that can cause increased vibration or rotation
can quench the fluorescence.
• The planar structure of fluorescent compounds allows delocalization of the 𝜋-electrons
in the molecule. That in turn increases the chance that luminescence can occur because
the electrons can move to the proper location to relax into a lower energy localized
orbital.
• Organic compounds that contain only single bonds between the carbons do not
luminesce owing to lack of absorption in the appropriate region and lack of a planar and
rigid structure.
• Organic compounds that do luminesce generally consist of rings with alternative single
and double bonds between the atoms (conjugated double bonds) in the rings.
• The sp2 bonds between the carbons in the rings cause the desired planar structure, and
the alternating double bonds give rigidity and provide the 𝜋-electrons necessary for
luminescence. 20
21. Effect Of Temperature
21
• The quantum efficiency of fluorescence in most molecules decreases with
increasing temperature
• Higher temperature result in larger collisional deactivation due to
increased movement and velocity of molecules.
• Therefore, lower temperature are preferred.
22. Effect Of PH
• The pH of the solution is a very important factor
• Fluorescence of an aromatic compound with acidic ring substituents is usually
pH-dependent.
• Both 𝛌 and the emission intensity are likely to be different for the ionized and
nonionized forms of the compound
For Example:
Aniline shows fluorescence, while Aniline in acid solution(anilinium ion) does
not
22
23. Cont.…
• Most compound luminesce in basic or slightly basic solution
• While some show fluorescence in acidic medium
• So, It is important to adjust pH to obtained maximum luminescence intensity
• pH also affect the emission wavelength, longer emission wavelength is
observed at higher pH
23
24. Effect Of Solvent Nature
Solvents characteristics have important effect on luminescent behavior of molecules.
• Three main effect can be recognized:
Solvent Polarity:
A polar solvent is preferred as the energy required for the π-π* is lowered.
SolventViscosity:
More viscous solvents are preferred since collisional deactivation will be lowered at higher
viscosities.
Heavy Atoms Effect
Fluorescence quantum efficiency will decrease, Phosphorescence will increase.
• Other solutes with such atoms in their structure; carbon tetrabromide and ethyl iodide are
examples.
• The effect is similar to what occurs when heavy atoms are substituted into fluorescing
compounds; orbital spin interactions result in an increase in the rate of triplet formation and a
corresponding decrease in fluorescence. 24
25. Effect Of Dissolved Oxygen
• Dissolved Oxygen largely limits fluorescence , since it promotes intersystem
crossing because it is paramagnetic.
• Dissolved Oxygen affects phosphorescence more than fluorescence
• As far as intersystem crossing is increased in the presence of oxygen,
phosphorescence is expected to increase.
On the contrary, phosphorescence is completely eliminated and quenched in
presence of dissolved oxygen.
• This may be explained on the basis that the ground state of oxygen is the triplet
state and is easier for an electron in the triplet state to transfer its energy to
triplet oxygen rather than performing flip in spin and relax to single.
• Therefore, oxygen will be excited and we really observe oxygen emission rather
than phosphorescence.
• For this reason oxygen should be totally excluded to detect phosphorescence
25
26. Effects Of Inner-Filter
• Fluorescence intensity will be reduced by the presence of any compound
which is capable of absorbing a portion of either the excitation or emission
energy.
• At high concentrations this can be caused by absorption due to the
fluorophore itself.
26
27. Quenching
• Interaction of the excited state of the fluorophore with its surroundings is
known as quenching
• Decreasing fluorescence intensity
• Relatively rare
• Quenching is not random
• Quinine fluorescence is quenched by the presence of halide ion despite the
fact that the absorption spectrum and extinction coefficient of quinine is
identical in 0.5M H2SO4 and 0.5M HCl.
27