Raman spectroscopy and its applications are summarized. Key techniques discussed include resonance Raman spectroscopy, Raman microscopy, and surface-enhanced Raman spectroscopy. Applications covered include medical use for tissue analysis, forensics for explosive or ink detection, inspection of packaged products, analysis of artworks, and testing of silicon wafers. The document outlines the principles, instrumentation, and mechanisms of various Raman techniques.
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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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
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.
Analytical Spectroscopic systems
Mass Spectrometry
Atomic mass to charge ratio
Laser Raman
Spectroscopy
Molecular vibrational modes
Laser Induced
Breakdown
Spectroscopy
Atomic emission
Visible Reflectance
Spectroscopy
Reflected color
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.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
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.
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APPLICATIONS OF
RAMAN
SPECTROSCOPY
Submitted by,
KAAVYA B
Holy Cross College,
Trichy 2
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• Resonance Raman Scattering
• Raman microscopy
• Surface Enhanced Raman scattering
• CARS
• Applications In
a) Medical
b) Forensic
c) Inspection of products
d) Art
e)Geology
f) Nanotechnology
• Conclusion 2
OUTLINE
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• Many substances, especially colored ones,
may absorb laser beam energy and generate
strong fluorescence, which contaminates
Raman spectrum.
• It was discovered that instead of fluorescence
some type of colored molecules could
produce strong Raman scattering at certain
condition.This effect is Resonance Raman.
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Resonance Raman Spectroscopy
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• In RRS the λ of incoming laser is selected
to coincide with an electronic transition of
the molecule or material.
• Raman signal is amplified for about 106
magnitude orders.
• Extensively used for biological molecules.
• Detection of dilution solution possible
(concentration—10-3 M)
• All kinds of samples are analyzed .
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• It can be used to measure the atomic
displacement between ground state &
excited state.
• It can be used in the analysis of air
pollutants,aerosol particles etc.,
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• Highly monochromatic tunable lasers are
used.
• Glass can be used for windows, lenses, and
other optical components.
• When resonance Raman spectra are recorded,
however, sample heating and photo-
bleaching can cause damage and a change to
the Raman spectrum obtained
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Instrumentation
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• Although scattered light leaves the sample
in all directions the collection of the
scattered light is achieved only over a
relatively small solid angle by a lens and
directed to the spectrograph and CCD
detector.
• The laser beam can be at any angle with
respect to the optical axis used to collect
Raman scattering.
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• The collected scattered radiation is focused
into a spectrograph, in which the light is
first collimated and then dispersed by a
diffraction grating and refocused onto a
CCD camera
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• It consists of optical microscope, and adds an
excitation laser, laser rejection filters, a
spectrometer or monochromator, and an
optical sensitive detector such as a charge-
coupled device (CCD)
• It uses 2 lasers---- one of them produces RR
spectrum & other monitors the position of the
objective over the sample through CCD.
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Raman Microscope
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• The optical microscope uses light to
magnify and identify samples while the
Raman spectrometer scatters light and
measures the excitation vibration.
• The back scattered radiation from the
sample is imagined on to the entrance slit
of a monochromator.
• The data by the computer gives details
regarding the sample at the position
monitored by the CCD camera. 12
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• Raman microscopy of inorganic specimens
such as rocks and ceramics can use a
broader range of excitation wavelengths.
• Optical microscope + Raman spectrometer
= high resolution images of small samples.
• It is useful in studying phase transition in
molecular crystals.
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• It is an ideal tool for trace analysis
• Better to study highly diluted solutions
• Raman signal can be amplified by the
adsorption of molecules in certain metallic
surfaces--- surface enhanced raman
scattering.
• It permits the study of surface interactions,
adsoption process, electrode reactions, single
molecule detection.
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Surface Enhanced Raman Spectroscopy
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• 2 mechanisms—
• A.Electromagnetic model: interactions
among the incident EM radiations with the
surfaces.
• B.Charge transfer/chemical model:
interactions between adsorbed molecules
with the metallic atoms involved in
adsorption.
• Greatest enhancement --when excitation λ
is near plasma frequency of metal. 17
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• Output is not linearly proportional to its
input.
• It can effectively reduce the influence of
fluorescence.
• Hyper Raman Spectroscopy, Coherent anti
stokes Raman Spectroscopy, Coherent stokes
Raman spectroscopy, Stimulated Raman gain
and inverse raman spectroscopy.
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Nonlinear Raman spectroscopy
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• When tunable lasers generate frequency
which equals the anti stokes scattering
frequency , there is a signal enhancement.
• And the vibrational transitions equals the
energy difference between the two light
sources.
• CARS signal is anti stokes region.
• It is useful for molecules with high
fluorescence effect.
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• Bio molecules are highly raman active due to
their non polar molecular structure, the
abundance of water do not interfere with the
spectra due to the extreme polarity of water
molecules.
• This dichotomy between the scattering cross
section of biological macromolecules and
water is what allows raman to be used on
both tissues.
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Medical
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• Quality control of crystalline silicon are
tested.
• Orientation of silicon molecular structure
will affect raman spectra.
• For pure crystalline silicon , there is only one
allowed molecular vibration peak 521cm-1
• If wafer undergoes any stress or strain
correspondingly the peak will reduce.
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Silicon Wafer Testing
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• Laser can be focused through optically
transparent packaging allowing the content
to be analyzed without opening it
• Ava spec mini weighs 175 grams and of
dimensions 95mm x65mm x20mm
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Inspection of products
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• Raman data can be obtained from almost any
surface, allowing minute traces of
explosives or a firearm’s discharge to be
detected without attempting to lift samples
from evidence.
• Raman spectroscopy is highly sensitive to
minute chemical differences between inks.
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Forensic
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• Identification of individual pigments and
their degradation product leads to
insight into the working method of
artist.
• It also gives information about the
original state of painting.
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ART
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• It helps us to know whether the sample
is polarizable or not.– Raman scattering
occur after a dipole is induced in a
molecule by the incident radiation.
• It also indicates the
compostion,structure,stability &
vibrational levels within the sample
• Concentration of the scatter is found.
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Conclusion
