SlideShare a Scribd company logo
Raman Spectrum.pptx
Raman Spectrum.pptx
SPECTROSCOPY
• Spectroscopy is that branch of science which
deals with the study of interaction of
electromagnetic radiations with matter
• When the different types of electromagnetic
radiations are arranged in order of their
increasing wavelengths or decreasing frequencies,
the complete arrangement is called
electromagnetic spectrum.
Raman Spectrum.pptx
Electromagnetic wave
One of the waves that are propagated by simultaneous periodic
variations of electric and magnetic field intensity and that
include radio waves, infrared, visible light, ultraviolet, X-rays,
and gamma rays
Concept of Polarisability in Raman Effect
• How molecule become polarised :
When a molecule interacts with electric field of
electromagnetic radiation, it undergoes distortion in its
electron cloud resulting in the formation of a dipole..
• Isotropically polarisable:
When spherically symmetrical molecule i.e. CH4, CCl4
etc. interacts with radiation, the electron forming the
bonds are displaced by an electric field symmetrically
in all directions. Thus molecule become polarised,
whatever will be the direction of applied electric field.
Anisotropically polarisable:
Non spherical molecules i.e. diatomic H2,
HCl, CO and linear polyatomic molecules CO2
,HC≡CH, etc. The electron forming the bonds
are more easily displaced by an electric field
applied in parallel or perpendicular to bond.
CLASSICAL THEORYOF RAMAN EFFECT
The induced dipole moment µ of polarized
molecule is given by:
P = αE ……(1)
α = polarisability of molecule
The electric field vector E is given by:
E = E0 sin 2πνt ……(2)
E0 = amplitude of oscillating electric field
ν = frequency of incident radiation
From (1) and (2)
P = αE0 sin 2πνt ……..(3)
As the molecule undergoes vibrational or rotational motion
with frequency νn ,the polarisabilty of the molecule changes
:
α =α0 + βsin2πνn t
α = equilibrium polarisabilty
β = rate of change of polarisabilty with vibration , then
eq. (3) can be written as:
P = (α0 + βsin2πνn t) (E0 sin 2πνt)
= α0E0 sin 2πνt + βE0 sin 2πνtsin2πνn t
P = α0E0 sin 2πνt +(1/2) βE0 {cos2π( ν-νn )t - cos2π( ν+νn )t}
Here, α0E0 sin 2πνt has frequency of incident radiation,
represents Rayleigh scattering . The (ν-νn ) represents
Stoke’s lines and (ν+νn ) represents anti Stoke’s lines
QUANTUM THEORY OF RAMAN EFFECT
hvi
• Molecule may deviate the photon without absorbing its energy
unmodified line.
• May absorb part of energy of incident photon modified Stokes
line.
• Molecule, itself being in an excited state, imparts some of its intrinsic
energy to incident photon modified Antistokes line.
Let a molecule of energy Ep be exposed to radiation (ν0) and after collision the
energy of molecule be Eq and the frequency of scattered photon be ν’.
From law of conservation of energy
hν0 + Ep + 1/2mv2 = hν’ + Eq + 1/2mv’2 …..(1)
Since, there is no change in temperature due to
collision so,
1/2mv2 =1/2mv’2
So equation (1) becomes
hν0 + Ep = hν’ + Eq
ν’ = ν0 + Ep- Eq/h
i. Ep = Eq, ν’=ν0 (unmodified line)
ii. Ep < Eq, ν’< ν0 (Stokes line)
iii. Ep > Eq, ν’> ν0 (Antistokes line)
What happens when light falls on a
material?
Rayleigh scattering is the scattering of light by the particles present in
the atmosphere. According to Rayleigh's scattering law, the amount of
scattering of the light is inversely proportional to the fourth power of
the wavelength. From the relation between scattering and wavelength,
we understand that shorter wavelengths scatter more. Since blue light
has a lesser wavelength than red light it scatters more.
Raman Spectrum.pptx
Raman Spectrum.pptx
• When a substance is irradiated
with monochromatic light, the light
scattered at right angles to the
incident light contained lines not
only of the incident frequency but
also of lower frequency and
sometimes of higher frequency as
well. The lines with lower
frequency are called Stokes' lines
whereas lines with higher
frequency are called anti-Stokes'
lines.
Raman Spectrum.pptx
Raman Spectrum.pptx
Raman Spectrum.pptx
Types of Vibration
Raman Spectrum.pptx
Raman Spectrum.pptx
Instrumentation
There are following component involves:
1. Laser or source of light
2. Filter
3. Sample holder
4. Detector
Raman Spectrum.pptx
1. Laser or source of light
• Lasers are strong source strong to detect Raman
scattering.
• Lasers operate using the principle of stimulated
emission.
• Electronic population inversion is required.
• Population inversion is achieved by “pumping”
using lots of photons in a variety of laser gain
media
2. Filter
For getting monochromatic radiations filters are
used.
They may be made of nickel oxide glass or quartz
glass.
Sometimes a suitable colored solution such as an
aqueous solution of iodine in CCl4 may be used as
a monochromator.
3. Sample holder
For the study of raman effect the type of sample
holder to be used depends upon the intensity of sources
,the nature and availability of the sample.
The study of raman spectra of gases requires
samples holders which are bigger in size than those for
liquids.
Solids are powdered or dissolved before subjecting to
Raman spectrograph.
Any solvents which is suitable for the ultraviolet
spectra can be used for the study of Raman spectra.
Water is regarded as good solvents for the study of
compounds in Raman spectroscopy.
4. Detector
Because of the weakness of a typical Raman signal.
Now days multichannel detectors like photodiode
arrays(PDA), charged couple devices(CCD) are
used.
Sensitivity & performance of modern CCD
detectors are high.
Selection Rule
• The polarisability of molecule must be change.
• For vibrational Raman spectra, the vibration must change
the polarisability of the molecule
∆v = ±1
where, ∆v = 1 corresponds to Stokes lines and
∆v = −1 corresponds toAnti-Stokes lines.
• For rotational Raman spectra, the polarisibilty of molecule
must be anisotropic.
∆J = 0, ±2
• All diatomic, linear and non spherical molecules are Raman
active.
• All spherical molecules are rotational Raman inactive. E.g
CH4 and CCl4 .
ADVANTAGES OF RAMAN OVER IR
•Raman lines are polarized.
•Raman spectra can be obtained even for molecules
such as O2, N2, CO2 etc. which have no permanent
dipole moment. Such a study has not been possible
by infra-red spectroscopy.
•Raman spectra can be obtained not only for gases
but even for liquids and solids whereas infra-red
spectra for liquids and solids are quite diffuse.
•Water can be used as solvent.
•Very suitable for biological samples in
native state (because water can be used as
solvent)
•Frequencies, spectrum is obtained using
visible light or NIR
•Glass and quartz lenses, cells, and optical
fibers can be used.
• Standard detectors can be used.
Disadvantages of Raman Spectroscopy
• Instrumentation is very expensive.
• Can not be used for metals or alloys.
• The Raman effect is very weak, so the detection
needs sensitive detectors.
• Fluorescense compounds when irradiated by the
laser beam, can hide the Raman spectrum.
• Sample heating through intenselaser
radiation can destroy the sample.
APPLICATIONS
• Application in inorganic chemistry
Vibrational spectroscopy still plays an important role
in inorganic systems. For example, some small reactive
molecules only exist in gas phase and XRD can only be
applied for solid state. Raman Spectroscopy is utilized to
study the structure of homonuclear diatomic molecules
(i.e. bond length) are all IR inactive
• Organic chemistry-
usеd to obtain information rеgarding thе prеsеncе or
absеncе of spеcific linkagеs in a molеculе, thе structurе
of simplе compounds, study of isomеrs (i.e. cis and
trans).
• Physical Chemistry-
helps to study physical chemistry concerning electrolytic
dissociation, hydrolysis and transition from crystalline
to amorphous state.
• Polymer Chemistry-
usеd for charactеrization of polymеr compounds,
by rеvеaling thе physical propеrtiеs and tacticity.
• Forensic science
including the identification of illicit drugs,
gunshot residue, inks used in explosives.
• Pharmaceutical Sector-
Raman Spectroscopy is widely adopted analytical technique in the
pharmaceutical market. . It can analyze excipients and active
pharmaceutical ingredients (APIs) of whole tablet within seconds,
to obtain an overview of the tablet through to a few tens of
micrometers to provide an in-depth analysis of individual grains
and phase boundaries.
• Biology-
• It helped to confirm the existence of low-
frequency phonons in proteins and DNA, and
their biological functions.
• used as a technique for, biochemical
characterization of wounds.
• used to detect cancer cells using bodily fluids
such as urine and blood samples

More Related Content

Similar to Raman Spectrum.pptx

Raman Spectroscopy
Raman SpectroscopyRaman Spectroscopy
Raman Spectroscopy
krishslide
 
raman spectroscopy
raman spectroscopyraman spectroscopy
raman spectroscopy
Saikumar Raja
 
Raman spectra.pdf
Raman spectra.pdfRaman spectra.pdf
Raman spectra.pdf
shembhuRampoonarSPME
 
NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY
NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPYNUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY
NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY
Asra Hameed
 
Analys is techniques
Analys is techniquesAnalys is techniques
Analys is techniques
ShreyaNair37
 
Nmr spectroscopy
Nmr spectroscopyNmr spectroscopy
Nmr spectroscopy
darshit1671998
 
Raman Spectra 2nd ppt.pptx
Raman Spectra 2nd ppt.pptxRaman Spectra 2nd ppt.pptx
Raman Spectra 2nd ppt.pptx
oviyaprabhu
 
Raman effect
Raman effectRaman effect
Raman effect
Manjula Rangachari
 
Spectroscopy
SpectroscopySpectroscopy
Spectroscopy
Mangalore University
 
Raman spectroscopy by nitish kumar
Raman spectroscopy by nitish kumarRaman spectroscopy by nitish kumar
Raman spectroscopy by nitish kumar
NITISH KUMAR
 
Raman spectroscopy
Raman spectroscopy Raman spectroscopy
Raman spectroscopy
Aravind AB
 
light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...
light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...
light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...
Sharath Hns
 
Raman spectroscopy
Raman spectroscopyRaman spectroscopy
Raman spectroscopy
Urvashi Arya
 
IR and NMR spectroscopy
IR and NMR spectroscopyIR and NMR spectroscopy
IR and NMR spectroscopy
Sulov Saha
 
uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS
 uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS
uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS
Harevindarsingh
 
Nmr lect
Nmr lectNmr lect
Nmr lect
Zainab&Sons
 
Nmr lect
Nmr lectNmr lect
Nmr lect
Zainab&Sons
 
Molecular spectroscopy-final engineering.pdf
Molecular spectroscopy-final engineering.pdfMolecular spectroscopy-final engineering.pdf
Molecular spectroscopy-final engineering.pdf
antoniostark0010
 
Spectroscpoic techniques
Spectroscpoic techniquesSpectroscpoic techniques
Spectroscpoic techniques
navaneethapulijala
 
Spectroscopy techniques, it's principle, types and applications
Spectroscopy techniques, it's principle, types and applications Spectroscopy techniques, it's principle, types and applications
Spectroscopy techniques, it's principle, types and applications
NizadSultana
 

Similar to Raman Spectrum.pptx (20)

Raman Spectroscopy
Raman SpectroscopyRaman Spectroscopy
Raman Spectroscopy
 
raman spectroscopy
raman spectroscopyraman spectroscopy
raman spectroscopy
 
Raman spectra.pdf
Raman spectra.pdfRaman spectra.pdf
Raman spectra.pdf
 
NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY
NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPYNUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY
NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY
 
Analys is techniques
Analys is techniquesAnalys is techniques
Analys is techniques
 
Nmr spectroscopy
Nmr spectroscopyNmr spectroscopy
Nmr spectroscopy
 
Raman Spectra 2nd ppt.pptx
Raman Spectra 2nd ppt.pptxRaman Spectra 2nd ppt.pptx
Raman Spectra 2nd ppt.pptx
 
Raman effect
Raman effectRaman effect
Raman effect
 
Spectroscopy
SpectroscopySpectroscopy
Spectroscopy
 
Raman spectroscopy by nitish kumar
Raman spectroscopy by nitish kumarRaman spectroscopy by nitish kumar
Raman spectroscopy by nitish kumar
 
Raman spectroscopy
Raman spectroscopy Raman spectroscopy
Raman spectroscopy
 
light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...
light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...
light emission spectroscopy,raman spectroscopy, flourimetry,flame photometry,...
 
Raman spectroscopy
Raman spectroscopyRaman spectroscopy
Raman spectroscopy
 
IR and NMR spectroscopy
IR and NMR spectroscopyIR and NMR spectroscopy
IR and NMR spectroscopy
 
uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS
 uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS
uv spectroscopy by HARVINDAR SINGH .M.PHARM PHARMACEUTICS
 
Nmr lect
Nmr lectNmr lect
Nmr lect
 
Nmr lect
Nmr lectNmr lect
Nmr lect
 
Molecular spectroscopy-final engineering.pdf
Molecular spectroscopy-final engineering.pdfMolecular spectroscopy-final engineering.pdf
Molecular spectroscopy-final engineering.pdf
 
Spectroscpoic techniques
Spectroscpoic techniquesSpectroscpoic techniques
Spectroscpoic techniques
 
Spectroscopy techniques, it's principle, types and applications
Spectroscopy techniques, it's principle, types and applications Spectroscopy techniques, it's principle, types and applications
Spectroscopy techniques, it's principle, types and applications
 

Recently uploaded

degree Certificate of Aston University
degree Certificate of Aston Universitydegree Certificate of Aston University
degree Certificate of Aston University
ebgyz
 
Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...
Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...
Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...
University of Maribor
 
largeintestinepathologiesconditions-240627071428-3c936a47 (2).pptx
largeintestinepathologiesconditions-240627071428-3c936a47 (2).pptxlargeintestinepathologiesconditions-240627071428-3c936a47 (2).pptx
largeintestinepathologiesconditions-240627071428-3c936a47 (2).pptx
muralinath2
 
Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...
Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...
Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...
Sérgio Sacani
 
The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...
The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...
The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...
Sérgio Sacani
 
Bragg Brentano Alignment for D4 with LynxEye Rev3.pptx
Bragg Brentano Alignment for D4 with LynxEye Rev3.pptxBragg Brentano Alignment for D4 with LynxEye Rev3.pptx
Bragg Brentano Alignment for D4 with LynxEye Rev3.pptx
Lisandro Cunci
 
Science-Technology Quiz (School Quiz 2024)
Science-Technology Quiz (School Quiz 2024)Science-Technology Quiz (School Quiz 2024)
Science-Technology Quiz (School Quiz 2024)
Kashyap J
 
Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...
Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...
Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...
Sérgio Sacani
 
El Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdf
El Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdfEl Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdf
El Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdf
Champs Elysee Roldan
 
A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....
A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....
A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....
Sérgio Sacani
 
Testing the Son of God Hypothesis (Jesus Christ)
Testing the Son of God Hypothesis (Jesus Christ)Testing the Son of God Hypothesis (Jesus Christ)
Testing the Son of God Hypothesis (Jesus Christ)
Robert Luk
 
The Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track
The Dynamical Origins of the Dark Comets and a Proposed Evolutionary TrackThe Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track
The Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track
Sérgio Sacani
 
Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...
Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...
Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...
Hossein Fani
 
poikilocytosis 23765437865210857453257844.pptx
poikilocytosis 23765437865210857453257844.pptxpoikilocytosis 23765437865210857453257844.pptx
poikilocytosis 23765437865210857453257844.pptx
muralinath2
 
SCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptx
SCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptxSCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptx
SCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptx
JoanaBanasen1
 
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...
Sérgio Sacani
 
poikilocytosis 237654378658585210854.pptx
poikilocytosis 237654378658585210854.pptxpoikilocytosis 237654378658585210854.pptx
poikilocytosis 237654378658585210854.pptx
muralinath2
 
Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanetHydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
Sérgio Sacani
 
A slightly oblate dark matter halo revealed by a retrograde precessing Galact...
A slightly oblate dark matter halo revealed by a retrograde precessing Galact...A slightly oblate dark matter halo revealed by a retrograde precessing Galact...
A slightly oblate dark matter halo revealed by a retrograde precessing Galact...
Sérgio Sacani
 
LOB LOD LOQ for method validation in laboratory
LOB LOD LOQ for method validation in laboratoryLOB LOD LOQ for method validation in laboratory
LOB LOD LOQ for method validation in laboratory
JCKH
 

Recently uploaded (20)

degree Certificate of Aston University
degree Certificate of Aston Universitydegree Certificate of Aston University
degree Certificate of Aston University
 
Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...
Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...
Deploying DAPHNE Computational Intelligence on EuroHPC Vega for Benchmarking ...
 
largeintestinepathologiesconditions-240627071428-3c936a47 (2).pptx
largeintestinepathologiesconditions-240627071428-3c936a47 (2).pptxlargeintestinepathologiesconditions-240627071428-3c936a47 (2).pptx
largeintestinepathologiesconditions-240627071428-3c936a47 (2).pptx
 
Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...
Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...
Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I ...
 
The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...
The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...
The cryptoterrestrial hypothesis: A case for scientific openness to a conceal...
 
Bragg Brentano Alignment for D4 with LynxEye Rev3.pptx
Bragg Brentano Alignment for D4 with LynxEye Rev3.pptxBragg Brentano Alignment for D4 with LynxEye Rev3.pptx
Bragg Brentano Alignment for D4 with LynxEye Rev3.pptx
 
Science-Technology Quiz (School Quiz 2024)
Science-Technology Quiz (School Quiz 2024)Science-Technology Quiz (School Quiz 2024)
Science-Technology Quiz (School Quiz 2024)
 
Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...
Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...
Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWS...
 
El Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdf
El Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdfEl Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdf
El Nuevo Cohete Ariane de la Agencia Espacial Europea-6_Media-Kit_english.pdf
 
A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....
A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....
A Strong He II λ1640 Emitter with an Extremely Blue UV Spectral Slope at z=8....
 
Testing the Son of God Hypothesis (Jesus Christ)
Testing the Son of God Hypothesis (Jesus Christ)Testing the Son of God Hypothesis (Jesus Christ)
Testing the Son of God Hypothesis (Jesus Christ)
 
The Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track
The Dynamical Origins of the Dark Comets and a Proposed Evolutionary TrackThe Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track
The Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track
 
Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...
Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...
Collaborative Team Recommendation for Skilled Users: Objectives, Techniques, ...
 
poikilocytosis 23765437865210857453257844.pptx
poikilocytosis 23765437865210857453257844.pptxpoikilocytosis 23765437865210857453257844.pptx
poikilocytosis 23765437865210857453257844.pptx
 
SCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptx
SCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptxSCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptx
SCIENTIFIC INVESTIGATIONS – THE IMPORTANCE OF FAIR TESTING.pptx
 
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regol...
 
poikilocytosis 237654378658585210854.pptx
poikilocytosis 237654378658585210854.pptxpoikilocytosis 237654378658585210854.pptx
poikilocytosis 237654378658585210854.pptx
 
Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanetHydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet
 
A slightly oblate dark matter halo revealed by a retrograde precessing Galact...
A slightly oblate dark matter halo revealed by a retrograde precessing Galact...A slightly oblate dark matter halo revealed by a retrograde precessing Galact...
A slightly oblate dark matter halo revealed by a retrograde precessing Galact...
 
LOB LOD LOQ for method validation in laboratory
LOB LOD LOQ for method validation in laboratoryLOB LOD LOQ for method validation in laboratory
LOB LOD LOQ for method validation in laboratory
 

Raman Spectrum.pptx

  • 3. SPECTROSCOPY • Spectroscopy is that branch of science which deals with the study of interaction of electromagnetic radiations with matter • When the different types of electromagnetic radiations are arranged in order of their increasing wavelengths or decreasing frequencies, the complete arrangement is called electromagnetic spectrum.
  • 5. Electromagnetic wave One of the waves that are propagated by simultaneous periodic variations of electric and magnetic field intensity and that include radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays
  • 6. Concept of Polarisability in Raman Effect • How molecule become polarised : When a molecule interacts with electric field of electromagnetic radiation, it undergoes distortion in its electron cloud resulting in the formation of a dipole.. • Isotropically polarisable: When spherically symmetrical molecule i.e. CH4, CCl4 etc. interacts with radiation, the electron forming the bonds are displaced by an electric field symmetrically in all directions. Thus molecule become polarised, whatever will be the direction of applied electric field.
  • 7. Anisotropically polarisable: Non spherical molecules i.e. diatomic H2, HCl, CO and linear polyatomic molecules CO2 ,HC≡CH, etc. The electron forming the bonds are more easily displaced by an electric field applied in parallel or perpendicular to bond.
  • 8. CLASSICAL THEORYOF RAMAN EFFECT The induced dipole moment µ of polarized molecule is given by: P = αE ……(1) α = polarisability of molecule The electric field vector E is given by: E = E0 sin 2πνt ……(2) E0 = amplitude of oscillating electric field ν = frequency of incident radiation From (1) and (2) P = αE0 sin 2πνt ……..(3)
  • 9. As the molecule undergoes vibrational or rotational motion with frequency νn ,the polarisabilty of the molecule changes : α =α0 + βsin2πνn t α = equilibrium polarisabilty β = rate of change of polarisabilty with vibration , then eq. (3) can be written as: P = (α0 + βsin2πνn t) (E0 sin 2πνt) = α0E0 sin 2πνt + βE0 sin 2πνtsin2πνn t P = α0E0 sin 2πνt +(1/2) βE0 {cos2π( ν-νn )t - cos2π( ν+νn )t} Here, α0E0 sin 2πνt has frequency of incident radiation, represents Rayleigh scattering . The (ν-νn ) represents Stoke’s lines and (ν+νn ) represents anti Stoke’s lines
  • 10. QUANTUM THEORY OF RAMAN EFFECT hvi • Molecule may deviate the photon without absorbing its energy unmodified line. • May absorb part of energy of incident photon modified Stokes line. • Molecule, itself being in an excited state, imparts some of its intrinsic energy to incident photon modified Antistokes line. Let a molecule of energy Ep be exposed to radiation (ν0) and after collision the energy of molecule be Eq and the frequency of scattered photon be ν’.
  • 11. From law of conservation of energy hν0 + Ep + 1/2mv2 = hν’ + Eq + 1/2mv’2 …..(1) Since, there is no change in temperature due to collision so, 1/2mv2 =1/2mv’2 So equation (1) becomes hν0 + Ep = hν’ + Eq ν’ = ν0 + Ep- Eq/h i. Ep = Eq, ν’=ν0 (unmodified line) ii. Ep < Eq, ν’< ν0 (Stokes line) iii. Ep > Eq, ν’> ν0 (Antistokes line)
  • 12. What happens when light falls on a material?
  • 13. Rayleigh scattering is the scattering of light by the particles present in the atmosphere. According to Rayleigh's scattering law, the amount of scattering of the light is inversely proportional to the fourth power of the wavelength. From the relation between scattering and wavelength, we understand that shorter wavelengths scatter more. Since blue light has a lesser wavelength than red light it scatters more.
  • 16. • When a substance is irradiated with monochromatic light, the light scattered at right angles to the incident light contained lines not only of the incident frequency but also of lower frequency and sometimes of higher frequency as well. The lines with lower frequency are called Stokes' lines whereas lines with higher frequency are called anti-Stokes' lines.
  • 23. Instrumentation There are following component involves: 1. Laser or source of light 2. Filter 3. Sample holder 4. Detector
  • 25. 1. Laser or source of light • Lasers are strong source strong to detect Raman scattering. • Lasers operate using the principle of stimulated emission. • Electronic population inversion is required. • Population inversion is achieved by “pumping” using lots of photons in a variety of laser gain media
  • 26. 2. Filter For getting monochromatic radiations filters are used. They may be made of nickel oxide glass or quartz glass. Sometimes a suitable colored solution such as an aqueous solution of iodine in CCl4 may be used as a monochromator.
  • 27. 3. Sample holder For the study of raman effect the type of sample holder to be used depends upon the intensity of sources ,the nature and availability of the sample. The study of raman spectra of gases requires samples holders which are bigger in size than those for liquids. Solids are powdered or dissolved before subjecting to Raman spectrograph. Any solvents which is suitable for the ultraviolet spectra can be used for the study of Raman spectra. Water is regarded as good solvents for the study of compounds in Raman spectroscopy.
  • 28. 4. Detector Because of the weakness of a typical Raman signal. Now days multichannel detectors like photodiode arrays(PDA), charged couple devices(CCD) are used. Sensitivity & performance of modern CCD detectors are high.
  • 29. Selection Rule • The polarisability of molecule must be change. • For vibrational Raman spectra, the vibration must change the polarisability of the molecule ∆v = ±1 where, ∆v = 1 corresponds to Stokes lines and ∆v = −1 corresponds toAnti-Stokes lines. • For rotational Raman spectra, the polarisibilty of molecule must be anisotropic. ∆J = 0, ±2 • All diatomic, linear and non spherical molecules are Raman active. • All spherical molecules are rotational Raman inactive. E.g CH4 and CCl4 .
  • 30. ADVANTAGES OF RAMAN OVER IR •Raman lines are polarized. •Raman spectra can be obtained even for molecules such as O2, N2, CO2 etc. which have no permanent dipole moment. Such a study has not been possible by infra-red spectroscopy. •Raman spectra can be obtained not only for gases but even for liquids and solids whereas infra-red spectra for liquids and solids are quite diffuse.
  • 31. •Water can be used as solvent. •Very suitable for biological samples in native state (because water can be used as solvent) •Frequencies, spectrum is obtained using visible light or NIR •Glass and quartz lenses, cells, and optical fibers can be used. • Standard detectors can be used.
  • 32. Disadvantages of Raman Spectroscopy • Instrumentation is very expensive. • Can not be used for metals or alloys. • The Raman effect is very weak, so the detection needs sensitive detectors. • Fluorescense compounds when irradiated by the laser beam, can hide the Raman spectrum. • Sample heating through intenselaser radiation can destroy the sample.
  • 33. APPLICATIONS • Application in inorganic chemistry Vibrational spectroscopy still plays an important role in inorganic systems. For example, some small reactive molecules only exist in gas phase and XRD can only be applied for solid state. Raman Spectroscopy is utilized to study the structure of homonuclear diatomic molecules (i.e. bond length) are all IR inactive
  • 34. • Organic chemistry- usеd to obtain information rеgarding thе prеsеncе or absеncе of spеcific linkagеs in a molеculе, thе structurе of simplе compounds, study of isomеrs (i.e. cis and trans). • Physical Chemistry- helps to study physical chemistry concerning electrolytic dissociation, hydrolysis and transition from crystalline to amorphous state.
  • 35. • Polymer Chemistry- usеd for charactеrization of polymеr compounds, by rеvеaling thе physical propеrtiеs and tacticity. • Forensic science including the identification of illicit drugs, gunshot residue, inks used in explosives.
  • 36. • Pharmaceutical Sector- Raman Spectroscopy is widely adopted analytical technique in the pharmaceutical market. . It can analyze excipients and active pharmaceutical ingredients (APIs) of whole tablet within seconds, to obtain an overview of the tablet through to a few tens of micrometers to provide an in-depth analysis of individual grains and phase boundaries.
  • 37. • Biology- • It helped to confirm the existence of low- frequency phonons in proteins and DNA, and their biological functions. • used as a technique for, biochemical characterization of wounds. • used to detect cancer cells using bodily fluids such as urine and blood samples