1) The document discusses nuclear magnetic resonance (NMR) spectroscopy and provides details on the theory, principles, instrumentation, and applications of NMR. It describes how NMR works based on the spin and magnetic properties of atomic nuclei.
2) The key components of an NMR instrument are described, including the magnet, radiofrequency transmitter and receiver coils, and detector. Common solvents used in NMR experiments are also listed, such as deuterated chloroform and benzene.
3) The concepts of relaxation processes and chemical shifts are explained. Relaxation involves the nuclei returning to equilibrium after excitation by radiofrequency pulses. Chemical shifts refer to small changes in resonant frequencies of different nuclei based on their chemical environment.
PRINCIPLES of FT-NMR & 13C NMR
Fourier Transform
FOURIER TRANSFORM NMR SPECTROSCOPY
THEORY OF FT-NMR
13C NMR SPECTROSCOPY
Principle
Why C13-NMR is required though we have H1-NMR?
CHARACTERISTIC FEATURES OF 13 C NMR
Chemical Shifts
NUCLEAR OVERHAUSER ENHANCEMENT
Short-Comings of 13C-NMR Spectra
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.
Quadrupole and Time of Flight Mass analysers.Gagangowda58
Description about important mass analysers Quadrupole and TOF: Principle, Construction and Working, Advantages and Disadvantages and their Applications.
PRINCIPLES of FT-NMR & 13C NMR
Fourier Transform
FOURIER TRANSFORM NMR SPECTROSCOPY
THEORY OF FT-NMR
13C NMR SPECTROSCOPY
Principle
Why C13-NMR is required though we have H1-NMR?
CHARACTERISTIC FEATURES OF 13 C NMR
Chemical Shifts
NUCLEAR OVERHAUSER ENHANCEMENT
Short-Comings of 13C-NMR Spectra
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.
Quadrupole and Time of Flight Mass analysers.Gagangowda58
Description about important mass analysers Quadrupole and TOF: Principle, Construction and Working, Advantages and Disadvantages and their Applications.
Mass spectroscopy
1.Introduction
2. Principle
3. Theory
4. Instrumentation
5. Different types of Ionization
6. FAB
7. MALDI
8. APCI
9. ESI
10.Quardapole
Introduction
working principle
fragmentation process
general rules for fragmentation
general modes of fragmentation
metastable ions
isotopic peaks
applications
Mass Analyzers for example Magnetic Sector Mass Analyzer, Double Focusing Mass Analyzer, Quadroupole Mass Analyzer, Time of Flight Mass Analyzer and Applications of Mass Analyzer were explained
1. contents - NMR SPECTROMETER
INTRUMENTATION OF NMR
COMPONENTS OF NMR SPECTROMETER
REFERENCES
2. NMR Spectrometer is an instrument which is used to obtain NMR Spectra.
A high resolution spectrometer contains a complex collection of electronic equipments.
NMR spectrometers are referred to as 300 MHz instruments (or) 500 MHz instruments, depending upon the frequency of the RF radiation used for resonance.
These spectrometers use very powerful magnets to create a small but measurable energy difference between two possible spin states.
3. COMPONENTS OF NMR SPECTROMETER
Magnet
Field Lock
Shim Coils
Probe Unit
- Sample Holder
- RF Oscillator
- Sweep Generator
- RF Receiver
Detector
Read out Device
4. magnets ;-
The heart of both continuous-wave and Fourier form NMR instruments is the magnet.
Magnets produces the magnetic field, which determines the frequency of any nucleus.
Sensitivity and resolution are critically dependent on quality of magnet.
It should give homogenous magnetic field, i.e. the strength of the magnetic field should not change from point to point.
The magnet must be capable of producing a very strong magnetic field with strength at least 10,000 gauss
5. Types of Magnets
Permanent Magnet:
Permanent magnets with field strengths of 0.7, 1.4, and 2.1 T are mostly used.
Permanent magnets are highly temperature-sensitive and require extensive thermostating and shielding as a consequence.
It is inexpensive and simple to operate.
They are operated up to 30 – 60 MHz
They provide field of good homogeneity.
Disadvantage:- Field variation is not possible, as required, because different nuclei resonate at different magnetic field.
6. Electro Magnets:
They require power supply to produce magnetic field
Cooling system is required to counter the heat generated from the electric power.
They are more effective than the permanent magnet because of possibility of field variation
They are operated up to 60 - 90 MHz
7. 3. Super conducting magnet:
A super conducting magnet has an electromagnet made up of superconducting wire.
These magnets attain fields large as 21 T.
Superconducting wire has a resistance approximately equal to zero by immersing it in liquid helium (at 0° c).
Superconducting magnet systems be filled with liquid nitrogen every 10 days
The length of superconducting wire in the magnet is typically several miles.
They are operated up to 470 MHz
8. field lock
In order to produce a high resolution NMR spectrum of a sample there is need of homogeneous magnetic field.
The field strength might vary due to aging of the magnet, movement of metal object near the magnet, and temperature fluctuations.
9. shim coils
Shim coils are pairs of wire loops.
By using these coils Current is adjusted until the magnetic field has required homogeneity.
Magnetic field produced by the Shim coils cancels the small residual inhomogeneities in the magnetic field.
Mass spectroscopy
1.Introduction
2. Principle
3. Theory
4. Instrumentation
5. Different types of Ionization
6. FAB
7. MALDI
8. APCI
9. ESI
10.Quardapole
Introduction
working principle
fragmentation process
general rules for fragmentation
general modes of fragmentation
metastable ions
isotopic peaks
applications
Mass Analyzers for example Magnetic Sector Mass Analyzer, Double Focusing Mass Analyzer, Quadroupole Mass Analyzer, Time of Flight Mass Analyzer and Applications of Mass Analyzer were explained
1. contents - NMR SPECTROMETER
INTRUMENTATION OF NMR
COMPONENTS OF NMR SPECTROMETER
REFERENCES
2. NMR Spectrometer is an instrument which is used to obtain NMR Spectra.
A high resolution spectrometer contains a complex collection of electronic equipments.
NMR spectrometers are referred to as 300 MHz instruments (or) 500 MHz instruments, depending upon the frequency of the RF radiation used for resonance.
These spectrometers use very powerful magnets to create a small but measurable energy difference between two possible spin states.
3. COMPONENTS OF NMR SPECTROMETER
Magnet
Field Lock
Shim Coils
Probe Unit
- Sample Holder
- RF Oscillator
- Sweep Generator
- RF Receiver
Detector
Read out Device
4. magnets ;-
The heart of both continuous-wave and Fourier form NMR instruments is the magnet.
Magnets produces the magnetic field, which determines the frequency of any nucleus.
Sensitivity and resolution are critically dependent on quality of magnet.
It should give homogenous magnetic field, i.e. the strength of the magnetic field should not change from point to point.
The magnet must be capable of producing a very strong magnetic field with strength at least 10,000 gauss
5. Types of Magnets
Permanent Magnet:
Permanent magnets with field strengths of 0.7, 1.4, and 2.1 T are mostly used.
Permanent magnets are highly temperature-sensitive and require extensive thermostating and shielding as a consequence.
It is inexpensive and simple to operate.
They are operated up to 30 – 60 MHz
They provide field of good homogeneity.
Disadvantage:- Field variation is not possible, as required, because different nuclei resonate at different magnetic field.
6. Electro Magnets:
They require power supply to produce magnetic field
Cooling system is required to counter the heat generated from the electric power.
They are more effective than the permanent magnet because of possibility of field variation
They are operated up to 60 - 90 MHz
7. 3. Super conducting magnet:
A super conducting magnet has an electromagnet made up of superconducting wire.
These magnets attain fields large as 21 T.
Superconducting wire has a resistance approximately equal to zero by immersing it in liquid helium (at 0° c).
Superconducting magnet systems be filled with liquid nitrogen every 10 days
The length of superconducting wire in the magnet is typically several miles.
They are operated up to 470 MHz
8. field lock
In order to produce a high resolution NMR spectrum of a sample there is need of homogeneous magnetic field.
The field strength might vary due to aging of the magnet, movement of metal object near the magnet, and temperature fluctuations.
9. shim coils
Shim coils are pairs of wire loops.
By using these coils Current is adjusted until the magnetic field has required homogeneity.
Magnetic field produced by the Shim coils cancels the small residual inhomogeneities in the magnetic field.
Explaining all the difficult concepts with precise and accurate points, 3D models, animations and smart art graphics.
Principle
The NMR phenomenon
Theory
Precessional frequency (ν)
Chemical shift
Spin-spin interactions
Interpretation of NMR
Chemical shift (δ)
Multiplicity of the signal
Coupling constant
Instrumentation
Fourier NMR
Continuous wave NMR
Applications
Identification testing
Assay of drugs
These slides comprised of following NMR points:
Introduction
Principle
Instrumentation
Working
Data Interpretation
Advantages
Disadvantages
Application
NMR - Nuclear magnetic resonance (NMR).pptxmuskaangandhi1
Nuclear magnetic resonance (NMR) spectroscopy is the study of molecules by recording the interaction of radiofrequency (Rf) electromagnetic radiations with the nuclei of molecules placed in a strong magnetic field.
It is concerned with absorption of certain amount of energy
by spinning nuclei in a magnetic field when irradiated with
radiofrequency radiation (RFR) of equivalent energy.
NMR gives the information about the number and configuration of
magnetically active atoms, like positions of different types
of Hydrogen over the C- skeleton of an organic molecule.
Absorption of RFR occurs when the nucleus undergoes
transition from one alignment in the applied magnetic field
to the opposite alignment, i.e. from parallel (ground state)
orientation to anti-parallel (excited state) orientation.
When the frequency of the oscillating electric field of the
incoming RFR just matches the frequency of the electric field
generated by the precising nucleus, then the 2 fields can
couple, and the energy can be transferred from the
incoming radiation to the nucleus, thus causing a spin change
(clock-wise to anti-clock-wise).
This condition is called "resonance", and the nucleus is said to
have resonance with the incoming electromagnetic wave
(RFR).
In NMR technique, the frequency of the RFR is kept constant
(60MHz) and the strength of magnetic field is varied.
At certain value of the applied field strength, depending
upon the nature of proton or nucleus, the energy required to
flip the proton matches the energy of radiation.
As a result, absorption takes place and a signal is observed
in the spectrum. Such a signal or peak is called an NMR
Spectrum.
NMR spectrum is graphical plot of relative intensity
(Y axis) and the δ value (x axis).
The nucleus of a hydrogen atom (proton) behaves as a spinning bar magnet because it possesses both electric and magnetic spin.
Like any other spinning charged body, the nucleus of hydrogen atom also generates a magnetic field.
Nuclear magnetic resonance Involves the interaction between an oscillating magnetic field of electromagnetic radiation and the magnetic energy of the hydrogen nucleus or some other type of nuclei when these are placed in an external static magnetic field.
The sample absorbs electromagnetic radiations in radio wave region at different frequencies since absorption depends upon the type of protons or certain nuclei contained in the sample)
Consider a spinning top. It also performs a slower waltz like motion,
in which the spinning axis of the top moves slowly around
the vertical.
This is processional motion & the top is said to be processing around the vertical axis of earth's gravitational field.
The precession arises from the interaction of spin with earth's gravity acting vertically downwards.
It is called Gyroscopic motion.
Proton will be showing processional motion due to interaction of Spin &
Gravitational force of Earth
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
3. INTRODUCTION
N
M
R
MEGNETIC
NUCLEAR RESONANCE
• Proton in nucleus shows spin movement because of that proton acts as small magnet
• Due to this the resonance in this small magnet takes place and processes NMR
• Range : 4-600 MHz
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4. QUANTUM NUMBER
AND THEIR ROLE
• Describe shape of
orbit .
• Value of I depends
on N.
• Have + or – value .
• Specify the orientation
• This number divides
the subshell into
individual orbital
which hold the
electron.
• Describes angular
momentum of
electron.
• Because angular
momentum is
vector spin
quantum number
has both
magnitude and
direction .
Definition:- occurs in the theoretical expression for the value of some quantized property of a subatomic
particle , atom or molecules and can only have certain integer or half integer value.
In simple term :- Quantum number is set of number use to describe position and energy of electron in atom.
It has 4 types
1. Principal(N) 2.Angular
momentum(I)
3.Magnetic(M) 4. Spin (S)
• The main energy
level occupied by
the electrons
• Energy level are
fixed distance from
nucleus of given
atom
• Described in whole
number
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6. • The theory behind NMR comes from the spin of a nucleus and it generates magnetic field.
• Without external applied magnetic field the nuclear spin are random in direction.
• When external magnetic field (B0) is present the nuclei aligned themselves either with or against the field of
external magnet.
Theory & Principle
THEORY
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8. The spinning nucleus
The effect of external magnetic field
Precessional motion
Precessional frequency
Energy transition
Theory & Principle
PRINCIPLE
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9. 1) THE SPINNING NUCLEUS:-
The nucleus of the hydrogen (proton)
behaves as a tiny spinning bar
magnet,
and it does so because it possesses
both electric charge and mechanical
spin
any spinning charged body will
generate a magnetic field, and the
nucleus of hydrogen is no exception
Theory & Principle
PRINCIPLE
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10. 2) The effect of external magnetic field
The proton can only adopt two orientations
with respect to an external magnetic
field-either aligned with the field (the
lower energy state)
Or
opposed to the field (the higher energy
state).
Theory & Principle
PRINCIPLE
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11. 3) Precessional motion
Proton will be showing precessional motion
due to interaction of spin & gravitational
force of earth [gyroscopic motion ]
Energy of reorientation of magnetic dipole
∆E=hv
Where ,
H= plank’s constant
V= frequency of radiation
Theory & Principle
PRINCIPLE
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12. 4) Precessional frequency
Spinning frequency of proton will be same
Precessional frequency ∝ external magnetic
force
v ∝ Bo
Theory & Principle
PRINCIPLE
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13. 5) Energy transition
If proton’s precessional frequency will be exactly same then only it will absorb the radiation and
resonance takes place which is know as NMR
Proton goes to low energy level to high energy level.
The emitted radiofrequency signal gives the NMR spectrum of the concerned nucleus.
The emitted radiofrequency is directly proportional to the strength of the applied magnetic field
Theory & Principle
PRINCIPLE
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16. INSTRUMENTATION
INSTRUMENTATION
1.SAMPLE HOLDER:
5mm GLASS TUBE IS USED,
WHICH CAN HOLD 0.4ml
LIQUID SAMPLE.
MICROTUBES ARE USED FOR
LOW VOLUMES.
2.MAGNET:
• ACCURACY & QUALITY OF THE INSTRUMENT IS DEPENDENT ON
ITS STRENGTH.
• RESOLUTION INCREASES WITH INCREASE IN THE FIELD
STRENGTH.
• THREE TYPES OF MAGNETS CAN BE USED
• CONVENTIONAL MAGNET (30 - 60MHz)
• PERMANENT MAGNET (60,90, 100MHz)
• SUPER CONDUCTING MAGNET (470MHz)
3.SWEEP GENERATOR:
A SET OF SWEEP COIL IS LOCATED PARALLEL TO THE
MAGNET, WHICH ALLOWS THE MAGNETIC FIELD TO SWEEP
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17. INSTRUMENTATION
INSTRUMENTATION
4. RF TRANSMITTER / GENERATOR :
• IT IS A PAIR OF COILS MOUNTED PERPENDICULAR
TO THE PATH OF FIELD & RECIEVER COIL.
5. RECIEVER COIL & AMPLIFIER:
• AMPLIFIES THE RECEIVED EMR BY 10 5
TIMES.
6. DETECTOR:
• DETECTS THE SIGNAL PRODUCED
BY RESONATING NUCLEI.
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18. SOLVENT USED
IN NMR
CRITERIAS
CHEMICALLY INERT
SOLVENTS SHOULD
BE MAGNETICALLY
ISOTROPIC IN
NATURE
FREE FROM ANY
HYDROGEN ATOM
SOLVENT SHOULD
BE ABLE TO
DISSOLVE THE
MOLECULARAMPLE
IN A RESONABLE
QUANTITY.
COMMONLY USED SOLVENTS:
CARBON TETRACHOLRIDE(CCL4)
CARBON DISULPHIDE(CS2)
DEUTEROCHLOROFORM(CDCI3)
HEXACHLOROACETONE((CDCI,),CO),
DEUTEROBENZENE(C;D.).
DEUTERODIMETHYLSULFOXIDE((CH;)250)
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19. RELEXATION
PROCESS
RELEXARION
PROCESS
RELAXATION IS PROCESS BY WHICH THE
SPINS IN THE SAMPLE COME TO
EQUILLIBRIUM WITH THE SURROUNDINGS.
RATE OF RELAXATION:
DETERMINES HOW FAST AN EXPERIMENT
CAN BE REPEATED
INFLUENCED BY THE PHYSICAL
PROPERTIES OF MOLECULE & THE SAMPLE
AN UNDERSTANDING OF RELAXATION
PROCESSES IS IMPORTANT FOR THE PROPER
MEASUREMENT & INTERPRETATION OF NMR
SPECTRA.
1. SPIN LETICE /LONGITUDINAL RELAXATION :
CHARACTERISED BY T1 NUCLEI IN UPPER
STATE STARTS TO LOSE ENERGY TO THE
SURROUNDING .
2.SPIN-SPIN/ TRANSVERSE RELAXATION:
CHARACTERISED BY T2 DOESN’T LEAD TO A
CHANGE IN UPPER & LOWER ENERGY LEVEL
NUCLEI IN THE UPPER STATE STARTS TO
TRANSFER ITS ENERGY TO A NUCLEI IN
LOWER ENERGY LEVEL.
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20. CHEMICAL SHIFT
CHEMICAL SHIFT
the chemical shift is the resonant frequency of an
atomic nucleus relative to a standard in a magnetic
field.
FACTORS INFLUENCING CHEMICAL
SHIFT
1. ELECTRONEGATIVITY -SHIELDlNG AND
DESHIELDING
2. VAN DER WAALS DESHIELDING
3. ANISOTROPIC EFFECTS
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