Raman Spectroscopy - Principle, Criteria, Instrumentation and ApplicationsPrabha Nagarajan
Basic principle of Raman scattering- Difference between Rayleigh and Raman Scattering- Major criteria for Raman active in compounds,-Stroke's lines and Anti-stoke lines- Difference and between IR and Raman spectroscopy- Wide applications of Raman spectroscopy.
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NQR - DEFINITION - ELECTRIC FIELD GRADIENT - NUCLEAR QUADRUPOLE MOMENT - NUCLEAR QUADRUPOLE COUPLING CONSTANT - PRINCIPLE OF NQR - ENERGY OF INTERACTION - SELECTION RULE - FREQUENCY OF TRANSITION - APPLICATIONS
It contains the basic principle of Mossbauer Spectroscopy.
Recoil energy, Dopler shift.
The instrumentation of Mossbauer Spectroscopy.
Hyperfine interactions.
Summary of operating principles of Surface Enhanced Raman Spectroscopy (SERS) instrumentation technique. Review of experimentation and results obtained using SERS in three scientific journals.
Raman Spectroscopy - Principle, Criteria, Instrumentation and ApplicationsPrabha Nagarajan
Basic principle of Raman scattering- Difference between Rayleigh and Raman Scattering- Major criteria for Raman active in compounds,-Stroke's lines and Anti-stoke lines- Difference and between IR and Raman spectroscopy- Wide applications of Raman spectroscopy.
CHECKOUT THIS NEW WEB BROWSER :
https://www.entireweb.com/?a=618b79ed612f3
NQR - DEFINITION - ELECTRIC FIELD GRADIENT - NUCLEAR QUADRUPOLE MOMENT - NUCLEAR QUADRUPOLE COUPLING CONSTANT - PRINCIPLE OF NQR - ENERGY OF INTERACTION - SELECTION RULE - FREQUENCY OF TRANSITION - APPLICATIONS
It contains the basic principle of Mossbauer Spectroscopy.
Recoil energy, Dopler shift.
The instrumentation of Mossbauer Spectroscopy.
Hyperfine interactions.
Summary of operating principles of Surface Enhanced Raman Spectroscopy (SERS) instrumentation technique. Review of experimentation and results obtained using SERS in three scientific journals.
Raman Spectroscopy is a non destructive chemical analysis technique which provides detailed information about chemical structure, crystallinity and molecular interactions. The raman effect involves scattering of light by molecules of gases, liquids, or solids. Raman Spectroscopy is sensitive to homo-nuclear molecular bonds. It is able to distinguish between single, double, and triple bonds between carbon atoms.Raman spectroscopy is the study of matter by the inelastic scattering of monochromatic
light. It has become a ubiquitous tool in modern spectroscopy, biophysics, microscopy, geochemistry, and analytical chemistry. In contrast to typical absorption or emission spectroscopy experiments, transitions among quantum levels of atoms or molecules are induced by the absorption or emission of photons (IR, visible, UV). In a typical Raman experiment, a polarized monochromatic light source (usually a laser) is focused into a sample, and the scattered light at 90 degree
to the laser beam is collected and dispersed by a high-resolution monochromator. The incident laser wavelength (chosen such that
the sample does not absorb, in ordinary Raman Spectroscopy) is fixed, and the scattered light is
dispersed and detected to obtain the frequency spectrum of the scattered light. The scattered light is very weak
(<10-7 of the incident power), so that monochromators with excellent straylight rejection and sensitive detectors are required. In a much rarer event (approximately 1 in 10million photons)Raman scattering occurs, which is an inelastic scattering process with a transfer of energy between the molecule and scattered photon. If the molecule gains energy from the photon during the scattering (excited to a higher
vibrational level) then the scattered photon loses energy and its wavelength increases which is called Stokes Raman scattering . Inversely, if the molecule loses energy by relaxing to alower vibrational level the scattered photon gains thecorresponding energy and its wavelength decreases;
which is called Anti-Stokes Raman scattering. • Quantum mechanically Stokes and Anti-Stokes areequally likely processes. However, with an ensemble of molecules, the majority of molecules will be in the ground vibrational level (Boltzmann distribution) and Stokes scatter is the statistically more probable process. As a result, the Stokes Raman scatter is always more intense than the anti-Stokes and for this
reason, it is nearly always the Stokes Raman scatter that is measured in Raman spectroscopy. Raman spectroscopy is used in chemistry to identify molecules and study chemical bonding and intramolecular bonds.In solid-state physics, Raman spectroscopy is used to characterize materials, measure temperature, and find the crystallographic orientation of a sample . In nanotechnology, a Raman microscope can be used to analyze nanowires to better understand their structures, and the radial breathing mode of carbon nanotubes is commonly used to evaluate their diameter.
Although the inelastic scattering of light was predicted by Adolf Smekal in 1923, it was not observed in practice until 1928. The Raman effect was named after one of its discoverers, the Indian scientist C. V. Raman, who observed the effect in organic liquids in 1928 together with K. S. Krishnan, and independently by Grigory Landsberg and Leonid Mandelstam in inorganic crystals. Raman won the Nobel Prize in Physics in 1930 for this discovery. The first observation of Raman spectra in gases was in 1929 by Franco Rasetti.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
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Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
4. “when we look at the
universe in a different „light‟
i.e., at „non visible‟ wave
length, we probe different
kinds of physical conditions
and we can see new kinds of
objects”
6. Spectroscopic data is often represented by a spectrum, a plot of
the intensity of radiation as a function of wavelength or frequency.
Spectrum of Benzene molecule
8. Sir Chandrasekhara Venkata Raman
. November 7, 1888 - November 21, 1970
. Won the Nobel prize in 1930 for Physics
. Discovered the “Raman effect”
. Besides discovering the Raman effect he
studied extensively in X-ray Diffractions,
Acoustics, Optics, Dielectrics and Colloidal
solutions.
9. When a monochromatic radiation of frequency ʋ is passed
through a non absorbing medium,it is found that most of it is
transmitted without any change, and some of it is scattered. If
the scattered energy is analyzed by means of a
spectrometer, the bulk of the energy is found at the frequency
of the incident beam ʋ˳ but a small portion of the scattered
energy will be
found at frequencies ʋ =ʋ˳ . The scattering of radiation
with change of frequency is called Raman scattering.
10. In Raman spectroscopy, by varying the frequency of
the radiation, a spectrum can be produced, showing the
intensity of the exiting radiation for each frequency.
This spectrum will show which frequencies of
radiation have been absorbed by the molecule to raise
it to higher vibrational energy states.
11. When Light hits a sample, It is Excited, and is
forced to vibrate and move. It is these vibrations
which we are measuring.
12. Atoms are at a certain energy level at any
given time.
As a laser light hits the atom, it is excited
and reaches a higher level of energy, and
then is brought back down.
If an atom is at a given energy level, it can
be excited then fall below the original
level.
Anti-stokes spectrum are mirror spectrums
of Stokes Raman Spectrums
13. Energy Scheme for Photon Scattering
Virtual
State
h 0 h 0+h
h h h m
Energy
0 0 0
h m
E0+h m
E0
IR Rayleigh Stokes Anti-Stokes
Absorption Scattering Scattering Scattering
(elastic)
Raman
(inelastic)
The Raman effect comprises a very small fraction,
about 1 in 107 of the incident photons.
14. Raman Spectrum
A Raman spectrum is a plot of the intensity of Raman
scattered radiation as a function of its frequency
difference from the incident radiation (usually in units
of wavenumbers, cm-1). This difference is called the
Raman shift.
19. Days before Laser..
Commonly used sources were 435.8nm and 253.6nm
emission lines of mercury vapour
Disadvantages
the source is an extended one and the brightness available per unit area is very
small
the relatively high frequency of mercury radiation often causes the sample to
fluorescence
as colored samples absorb in this high frequency region, it is not possible to record
their spectra
20. With the discovery of lasers …
Advantages
excellent monochromaticity
good beam focusing capabilities and small
line widths
the second order Raman spectra can be
recorded
the broadening due to Doppler effect can be
minimized
22. Lasers using in Raman spectroscopy
Laser sources for Raman spectroscopy include laser
diodes, diode-pumped lasers and ion lasers.
The Innova 300C and 70C series of small-frame argon or
krypton ion lasers are also well suited for Raman
experiments in the visible region of the spectrum.
Innova 70C Spectrum is a mixed gas lasers that can generate
a number of laser lines from the UV to the near IR
23. Laser wavelengths ranging from ultra-violet through
visible to near infra-red can be used for Raman
spectroscopy.
Typical examples include,
Ultra-violet: 244 nm, 257 nm, 325 nm, 364 nm
Visible: 457 nm, 473 nm, 488 nm, 514 nm, 532
nm, 633 nm, 660 nm
Near infra-red: 785 nm, 830 nm, 980 nm, 1064 nm
24. The Invictus 785-nm NIR laser is the excitation laser
of choice for the majority of Raman spectroscopy
applications from pharmaceutical to polymers.
The Invictus 830-nm NIR laser has been developed
for biomedical applications of Raman spectroscopy
where sample absorption characteristics require longer
excitation wavelengths and reduced spectral range.
The Invictus 532-nm VIS laser is used for specific
classes of Raman spectroscopy including gas phase
measurements.
25. The choice of laser wavelength has an
important impact on experimental capabilities:
Sensitivity
Spatial resolution
Optimisation of resulting based on sample
behaviour.
26. Laser filters using in Raman spectroscopy
Optical filters
Edge
Holographic notch
27. Gratings using in Raman spectroscopy
Typical gratings used for Raman vary from perhaps 300gr/mm
(low resolution) through to 1800gr/mm (high resolution) – more
specialised gratings (including 2400gr/mm and 3600gr/mm) are
also available, but have certain limitations, and should not be
considered general purpose.
Raman spectrometers typically use holographic gratings, which
normally have much less manufacturing defects in their
structure than ruled gratings. Stray light produced by
holographic gratings is about an order of magnitude less intense
than from the ruled gratings of the same groove density.
28. Detectors used in Raman spectroscopy
Charge Coupled Device (CCD) detector is the “camera” used
to detect the Raman spectrum. A CCD detector is a two
dimensional array of very low noise, silicon detectors.
Typical CCD chip.
30. Applications of Raman spectroscopy
Raman spectroscopy is commonly used in chemistry, since vibrational
information is specific to the chemical bonds and symmetry of
molecules. Therefore, it provides a fingerprint by which the molecule
can be identified.
In solid-state physics, spontaneous Raman spectroscopy is used
to, characterize materials, measure temperature, and find the
crystallographic orientation of a sample.
Raman spectroscopy can be used to observe other low frequency
excitations of the solid, such as plasmons, magnons, and
superconducting gap excitations
31. Spatially-offset Raman spectroscopy (SORS), which is less
sensitive to surface layers than conventional Raman, can be used to
discover counterfeit drugs without opening their packaging, and for
non-invasive monitoring of biological tissue
Raman spectroscopy can be used to investigate the chemical
composition of historical documents such as and contribute to
knowledge of the social and economic conditions at the time the
documents were produced.
Raman spectroscopy is being investigated as a means to detect
explosives for airport security.
32. Raman spectroscopy can be used as a technique
for identification of seafloor hydrothermal and
cold seep minerals
Used to discriminate between healthy and
unhealthy tissues, or to determine the degree of
progress of a certain disease.
Used in medicine , aiming to the development of
new therapeutic drugs and in the diagnosis of
arteriosclerosis and cancer.
33. References
Colin N. Banwell, Elaine M.McCash, 1994.
Fundamentals of Spectroscopy, Tata McGraw-Hill
Publishing Company Limited, New Delhi, 308p.
B B Laud, 1991.Lasers and non linear
optics, New age International(P) Limited, New
Delhi,261p.
H S Randhawa, 2003. Modern Molecular
Spectroscopy, Macmillan India LTD, New
Delhi,584p.