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18 views

Deconvoluting Raman spectras from different wavelengths

I am using a laser source that is wider than typical laser source for Raman spectroscopy. This mean that the full width at half maximum (FWHM) of the laser is about 5-10 nm, compared to the normal 1-3 ...
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6 views

How to determine the mean coupling constant of a crystal based on the energy of its phonon modes?

I'm doing lab work on raman spectroscopy and I was asked to determine the mean coupling constant C+ from the experimental results (see graph), but I don't really know how to. Can someone explain how ...
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35 views

How to deal with coma and oblique spherical aberration in a Czerny Turner configuration?

I am modelling my own spectrometer using Zemax when all of a sudden I've been told that: even if you manage to optimize the angles or positions of the grating and the mirrors, you won't get ...
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1answer
83 views

What are the purposes of slits inside a spectrometer (Czerny-Turner)?

I am building a Raman spectrometer with a Czerny Turner configuration (with RamanPi). Why does the light source (A) appear to be converging into the entrance slit (B)? When a sample is excited by ...
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1answer
71 views

What is the relationship between Raman peaks and phonon vibration modes?

I've seen Raman spectra, such as here, where peaks at certain wavenumbers were identified with phonon vibration modes (TO, LO, TA, LA). What is the relationship behind this, and how could I make such ...
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21 views

Resonance Raman scattering vs. absorption

I cannot understand resonance Raman scattering. It happens when there is a photon with resonant energy which is the same condition for absorption. How does the molecule "decide" if the photon is ...
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1answer
117 views

What is harmonic and fundamental bands in IR spectroscopy?

What is harmonic and fundamental bands in IR spectroscopy? I'm trying to find exact definitions. I guess that fundamental is $1\leftarrow 0$ transition (the most intense and energetic) and harmonic ...
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25 views

Raman amplification

Recently I read a bit about Raman amplification. Unfortunately, I did not understand everything. As far as I understood the resulting wavelength only depends on the pumping wavelength. Now I heard on ...
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1answer
409 views

What is a virtual state?

In quantum mechanics / Raman spectroscopy, what is a virtual state? What is the difference between a virtual state and a superposition of states? Can you simply think of the virtual state as a ...
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43 views

Quantum description of Raman effect

In the classical description of Raman effect the object of study is the electric polarizability of the system. Since I'm interested in learning the quantum description of the Raman effect and in ...
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1answer
26 views

Do the characteristic vibrational modes of a material define how much will a material heat up upon radiation excitation?

Do, and if yes how, does the intensity and energy of the Raman modes of a material make it to heat more by radiation excitation. I see phonons and vibrations of the lattice as heat, but maybe I'm ...
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1answer
67 views

Usage of the terms Raman, Stokes and anti-Stokes scattering

I am confused over the correct usage of the terminology for "Raman scattering", "Stokes scattering", "anti-Stokes scattering", or even "Stokes-Raman scattering" and "anti-Stokes-Raman scattering". Is ...
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1answer
31 views

CARS microscopy

I have probably very naive question. In case of CARS microscopy http://en.wikipedia.org/wiki/Coherent_anti-Stokes_Raman_spectroscopy we have $ω_{pr}+ω_{p}-ω_{S}$, how can we have minus $ω_S$? In ...
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4answers
359 views

What's the difference between Raman scattering and second harmonic generation in crystal?

As far as I know, the Raman scattering is from the stokes and anti-stokes scattering that the laser light interact with molecular vibrations. So we know that ""laser light interact with molecular ...
2
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1answer
118 views

Phonon scattering process in raman spectroscopy

I am trying to understand diagrams that involve showing phonon scattering processes that contribute to raman spectroscopy peaks. For example, I drew the one at the bottom of this post. This is ...
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0answers
155 views

Looking for raw interferogram data / raw FID data from FT-IR / FT-NIR / FT-NMR

I'm trying to get my hands on some raw interferogram data / raw FID data from an FT-IR / FT-NIR / FT-NMR so I can run some tests using FFT with it (it needs to be real data). Here's a picture below of ...
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1answer
101 views

What happens to the $2\pi$ factor when calculating Raman-shifts in units of wavenumbers?

So from the classical theory, you find a formula for a dipole in a planar electromagnetic wave, where there will be two cosine terms with a frequency (actually angular velocity in $[rad/s]$, as the ...
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0answers
90 views

Are metal modes mixed with molecular modes during surface enhanced Raman effect?

This question is dedicated to Martin Fleischmann (1927-2012). When a molecule is adsorbed on a metal surface, the Raman scattering amplitude from the molecule is enhanced. According to Wikipedia, the ...