Questions tagged [raman-spectroscopy]

A spectroscopic technique typically used to determine vibrational modes of molecules (or rotational and other low-frequency modes of systems). Commonly used in chemistry to provide a structural fingerprint by which molecules can be identified.

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Ratio between Stokes and anti-Stokes scattering amplitudes in Raman scattering

I'm trying to understand the amplitudes and the ratio between those of Stokes and anti-Stokes scattering in Raman scattering. I understand that from a Boltzmann distribution point of view, the ratio ...
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Beats and Raman effect

I have some doubts on Raman effect: if we have a diatomic molecule and we want to see Raman effect, we can send an electric field $E(t)=E_0cos(\omega_pt)$ on the molecule which has, due to vibrational ...
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What resources are you aware of and can recommend me to study and model spectral diffusion?

I am looking for textbooks, papers, etc. that cover this topic in some detail and would allow me to develop a simple model to use in my BSc thesis. I'm having a hard time finding the resources I need. ...
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Raman scattering collection geometry

I believe that most Raman spectroscopy measurements are carried out with the collection optics being at either 180$^{\circ}$(back-scattering) or 90$^{\circ}$ from the excitation source. Are there any ...
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Can infrared radiation be used to enhance Anti-Stokes Raman?

I read that anti-stokes Raman is much weaker than stokes Raman at room temperature because the vibrational states are less populated than ground state(Boltzmann distribution). Does this mean that if I ...
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Can raman be used to know the number of layers other than graphene?

I came across some paper where the number of layers of Graphene have been investigated by Raman spectroscopy. I found simulation websites https://instanano.com/characterization/calculator/raman/...
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How can Raman Spectra be utilised to know the crystal structure?

If Raman spectroscopy is using a visible or infrared source to excite phonons in the crystal, that is much different from XRD which is using higher energy X-rays scattered from the crystal planes. How ...
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Are virtual states eigenstates of physical observables?

In quantum mechanics, physical observables are represented by self-adjoint operators. A "virtual state" is supposedly a state which is unmeasurable, due to being too "short lived"....
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What's the difference between inelastic X-rays scattering and Raman scattering?

In solids, inelastic scattering of X-rays can produce or absorb a phonon, which is equivalent to saying that solid ends up in excited vibrational level ( or if it was in a vibrational level to begin ...
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What are 'internal' and 'external' modes of vibration?

I was reading about Raman spectroscopy for crystals. I have come across these two terms: internal and external modes of vibrations in crystal. I have no clue what they might mean. I am looking for a ...
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Why are spectrums of incandescent light bulbs continuous despite the presence of Argon around them?

Incandescent bulbs emit light by heating a filament using electricity, this would lead to a continuous spectrum according to Kirchoff's first law. However, the glass casing around the filament is ...
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Raman Spectroscopy and Phonon Modes

How can someone use Raman Spectroscopy to obtain information for the phonon modes of a crystal? I am asking for some paper that contains information about Raman Spectroscopy and Phonons from an ...
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Diffraction grating: Why does the light need to be in-phase?

I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter J. Larkin. Section 1.1 Dispersive Systems of chapter 3 says the following: A monochromator consists of an ...
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Laser flux power density and Raman scattered radiation

I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled The Raman Scattering Process, the author says the following: The intensity of ...
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Rayleigh scattering and Raman scattering observed intensities

I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled The Raman Scattering Process, the author says the following: Both Rayleigh ...
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The typical IR spectrometer broadband source emits all IR frequencies of interest simultaneously

I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled Infrared Absorption Process, the author says the following: The typical IR ...
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Complex dielectric function and normal reflectance

I am currently studying the textbook Surface Enhanced Raman Spectroscopy -- Analytical, Biophysical, and Life Science Applications by Sebastian Schlücker, Wolfgang Kiefer. Chapter 1.2.2 Planar ...
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Selection rules in spectroscopy

I am reading 'Fundamentals of Molecular spectroscopy' by Banwell-McCash and in different sections, one come across these selection rules for the allowed transitions but the book doesn't derive or ...
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Constrained Brilloiun zone sum to integral

In order to evaluate the two-phonon Raman scattering cross section I'm trying to compute the following double sum in $ k $-space (See Phys. Rev. B 17, 4951 (1978), or the book Light Scattering in ...
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Molecular Rotational energies and frequencies of diatomic molecule

I am studying Raman spectroscopy (I am still in the introduction though), and I wish to find the rotational and vibrational energies and frequencies for a diatomic molecule, say $0_2$. From the ...
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Why would $B_{1g}$ Raman mode still exist under $D_{4h}$ where $xx = yy$?

I come across some issues about Raman tensors under high symmetry , e.g. $D_{4h}$. A preliminary thought tells me that $x$ and $y$ are supposed to be equivalent in this point group therefore the Raman ...
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Selection rules in rotational spectroscopy- water molecule

The University of Liverpool maintains a ChemTube 3D page, where it says http://www.chemtube3d.com/spectrorotcd0-CE-TEST-ROTATE-ALL.html *> Highly symmetric polyatomic molecules, such as carbon ...
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Raman effect and IR absorption

Let's consider a molecule with N atoms, on which is shot a polychromatic IR beam. From the quantum selection rules, we know that in a single event of absorption only one of the 3N-6 oscillators can be ...
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How to find out the temperature of phonons using the Raman anti-Stokes and Stoke intensities ratio?

Basically the title, the concept is simple, but I`m having a hard time trying to9 find an explicit solution.
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Why can't there be a direct absorption of a photon between Raman active states?

My question pertains to the fundamental difference between Raman spectroscopy and IR spectroscopy. Simply put, the Raman active transitions correspond to a change in the polarizability of the molecule ...
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How to determine if a calculated Raman mode in a crystal is active or not?

I have used an ab initio electronic structure code to calculate the harmonic Raman spectrum of a (molecular) crystal. However, no use of symmetry has been made, and it might well be that some of the ...
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How to explain about Raman spectroscopy?

What is the definition of Raman spectroscopy? How to explain in brief about antistoke line and Stoke line and Rayleigh?
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How are Maxwell equations satisfied when inelastic scattering occurs?

Consider two media, A and B (example air/dieletric). One finds conditions that the $\vec E$ and $\vec B$ fields must satisfy at the interface, namely $\hat n_\text{A-B}\times(\vec E_A-\vec E_B) = \vec ...
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Cannot observe Raman signal from Styrofoam

I am trying to build a low cost Raman spectrometer. I am using a refurbished B&WTek spectrometer that I purchased from eBay. I calibrated the unit myself and found to be very sensitive and ...
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Why is the Raman spectrum continuous?

A typical Raman spectrum looks something like this with peaks and a background. I would like to know (1) What is the reason for that background? (2) When I took spectra with quartz the background was ...
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How can I estimate the penetration depth of a laser in gallium oxide?

I am searching for a way to estimate the penetration depth of a laser with wavelength $\lambda$ in gallium oxide (Ga$_2$O$_3$) in a Raman setup, in order to know the depth at which I am probing. ...
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What is the difference between the dipole in IR and Raman vibrations?

In order for a vibration to be IR active, there must be a change in the dipole moment ($\mu$) of the molecule, which is given by: $\mu$ = $\sum$ q * r Where q is the charge magnitude and r is the ...
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How do I calculate the wavenumbers for a Broadband CARS system?

I had the question when I was reading a paper by Camp (High-Speed Coherent Raman Fingerprint Imaging of Biological Tissues), and I've been researching how to calculate wavenumbers from the 4 wave ...
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D-peak of Raman Spectra of Graphite explanation

The D peak in the Raman Spectrum of Graphite is attributed to the breathing mode of $A_{1g)$ symmetry involving phonons near zone boundary. The explanation is the following: The change of bond ...
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Raman Scattering vs. Fluorescence (1-photon / 2-photon process) [duplicate]

I have a question considering the difference between Raman Scattering and fluorescence. I know that Raman Scataring is a non-resonant process, while fluorescence is resonant, that Raman scattering ...
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Is there any good tutorial on how to read, convert and process .spc files using Python, R, Ruby, Java?

Is there any good tutorial on how to read, convert and process .spc files using Python, R, Ruby, Java? Need to extract content of 30 .spc vibrational spectroscopy files to do PCA and descriptive ...
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Lorentz distribution in emission peaks

Sometimes spectral peaks are fitted using a very pathological function named the Lorentz/Cauchy distribution. The Lorentz distribution has the property of not having a defined mean nor standard ...
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Classical treatment of Raman effect

I found the classical treatment of Raman effect as described here very intuitive and helpful considering I have no training in quantum physics. I have two related questions: 1) In absence of varying ...
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2 answers
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How does Raman scattering not break energy quantization?

I understand how Raman scattering works and I understand that it can only be clearly explained if you think about light as a wave instead of a particle (otherwise you have to start talking about "...
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Time of re-emission of a photon in Raman scattering?

In Raman scatering events, when a photon is absorbed by a molecule, how much time(in average for small molecules) does it stay in the Virtual Energy State caused by the absorption.
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What does it mean if there's no peaks on raman spectrum?

I carried out Raman measurements of a doped semiconductor. I know what are the peaks of undoped one. I also know, that usually doped semiconductor has at least few peaks in similar positions to the ...
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How can electronic transitions in atoms contribute to the vibration of molecules?

In Raman spectroscopy, light is inelastically scattered from a sample and the shift in the scattered frequency (the Raman shift) is related to the vibrational modes of the sample. [...] and should ...
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Raman vs Fluorescence, scattering vs absorption, classical vs quantum [duplicate]

I am trying to grasp the difference between Raman scattering and fluorescence. To me it appears that the former is described in a somewhat more classical context as ordinary inelastic scattering, ...
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Understanding Depolarisation Ratio in Raman Spectroscopy

So the depolarisation ratio is given by the ratio of the scattered intensities \begin{equation} \rho = \frac{I_{\text{perpendicular}}}{I_\text{parallel}} \end{equation} My understanding of this is ...
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Which of these reasons are causes for the Stokes effect in Raman Scattering and/or Luminescence?

I’ve read several reasons for the Stokes effect and I can’t make out which of these are the true causes. Which of these apply to Raman or Luminescence or both? Are some of these the same thing? At ...
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Decoding the character table

The following is character table of water molecule I would like to know (1)What does the last 2 column in the table indicate? (2) How to deduce the functions in the last column?
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Do Raman spectra of crystals depend on stress, strain or both?

Very fundamental question. I always assumed that the spectra changes, because one changes the inter-atomic distances (strain) only. However, I am not sure this is the entire story. Does Raman ...
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Origin of Selection Rules for Rotational Raman spectra

I am aware of the fact that selection rules for transitions between two different quantum states, are obtained via an assessment of the corresponding transition matrix elements [1,2]. When we ...
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Baseline correction algorithm for Raman spectra. Raman baseline removal

Can someone please help with baseline correction algorithm? My task is to build an algorithm that normalizes baseline of spectrum WITHOUT using any additional software like Mathematica etc. I have a ...
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Second order spectra vs First order

Can someone explain for dummies what these are? How they are seen? And how to distinguish them? Perhaps, post some images. Thanks.
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