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Questions tagged [raman]

For questions relating to Raman scattering/effect and its applications as spectroscopy technique.

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Do these Raman scan output files really belong to the same exact Raman scan?

What I have got: Two files from First Defender’s system named Scan227-dark.spc and Scan227.spc. Plain text versions of both files: plaintextOfScan227-darkspc.txt and plaintextOfScan227spc.txt. Image ...
AbelBp's user avatar
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1 vote
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electronic properties simulation from experimental structure, good idea?

Good day to everyone ! I am currently in a physical chemistry internship trying to simulate a Raman spectrum of a molecular crystal using DFTB. Innocently, I directly tried to calculate the normal ...
Nectarion's user avatar
1 vote
0 answers
23 views

How to remove the baseline in the Raman spectrum without falsifying the spectral data. Measurement of anisotropy using SERS

My goal is to study the anisotropy of the sample based on changes in the Raman spectrum as a function of angle. The sample was rotated around the Z-axis and changes in the spectra are visible in the ...
Friszbot's user avatar
2 votes
0 answers
43 views

Source(s) of extreme Raman scattering of FeOOH under intense laser excitation?

RRUFF's Raman spectrum of FeO(OH) as Goethite: Bears no apparent similarity to the extreme Raman scattering of this sample of purported FeOOH under 785nm laser excitation with 100x objective that ...
James Bowery's user avatar
1 vote
0 answers
38 views

How to get Raman shift frequency values from neutron scattering measurements?

I have read some papers that say that a Kohn anomaly mode is a particular feature of 2H- transition metal dichalcogenides and that the existence of such a mode can be seen in neutron scattering data ...
John's user avatar
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2 votes
1 answer
197 views

Is there a difference between $A_{1g}$ modes and $A_{g}$ modes?

I know that both are totally symmetric and that the '$1$', according to the Mulliken table, refers to symmetry around the $C_2$ axis but I was reading some papers and found that modes were sometimes ...
John's user avatar
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3 votes
1 answer
47 views

Are A1g modes reduced at 180 degrees polarisation in Raman spectra?

I have read that A1g modes are identifiable in Raman spectra by looking at cross-polarised Raman spectra and seeing peaks that strongly reduce in intensity. So essentially, the intensity of A1g modes ...
John's user avatar
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1 vote
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73 views

IR / Raman factor group analysis (site and factor group determination)

I'm currently trying to interpret some IR and Raman spectra of solid state compounds. They show a simple molecular unit of which the expected bands are split due to the coordination in the crystal ...
Justanotherchemist's user avatar
1 vote
0 answers
39 views

Raman spectra of peptide

This is my first time measuring Raman spectra of a peptide sample. It is in solid form. I do think I see some Raman peaks but I am not sure how to assign them. I have a peptide sequence through which ...
Mukul Sharma's user avatar
2 votes
0 answers
57 views

What causes horizontal lines on an excitation-emission matrix in fluorometry?

I am doing excitation-emission matrices to test for CDOM, and we just got some brand new quarts cuvettes. When I hold them in front of a light, they're totally clear and clean. I ran a sample, and in ...
dogman's user avatar
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99 views

Finding wavelength of the centre of Stokes Ro-vibrational spectrum

I have the following rovibrational Raman spectrum for $N_2$: and I am trying to calculate the "wavelength where the centre of the Stokes ro-vibrational spectrum would be observed" if the $...
Allod's user avatar
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1 answer
463 views

Can you measure an IR spectrum of a sample inside a glass vial?

If I have a sample of some compounds dissolved in water inside a glass vial (let's say quartz). Would it be possible to get a usable measurement through this glass vial without too much absorption by ...
Tino Petersson's user avatar
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0 answers
434 views

Raman or FTIR spectroscopy to identify metals?

Metals are opaque, so doesn't most of the light reflect? And does the IR source even cause vibrations in the metal? Same goes for Raman spectroscopy, is it useful for use of metal identification? Is ...
Paperreader's user avatar
-1 votes
1 answer
145 views

Converting Raman Spectra to Infrared Spectra [closed]

I have data for detecting a substance using Raman spectra, but in production, I plan to be using a visible & near-infrared spectrometer. Would it be possible for me to convert from the Raman ...
ricky2020's user avatar
1 vote
1 answer
84 views

Raman scattering and "electron and proton center" of molecule

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: Light scattering ...
The Pointer's user avatar
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2 votes
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50 views

Convoluted explanation of different types of Raman scattering

I am currently studying the textbook Surface-Enhanced Raman Spectroscopy -- Bioanalytical, Biomolecular and Medical Applications by Marek Procházka. I just read this passage from chapter 2: Rayleigh ...
The Pointer's user avatar
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1 vote
1 answer
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CNT Raman ratio of G band to 2D band?

I believe that the G band (~1600 cm-1) shows the stretching mode of the graphene in a carbon nanotube (e.g. chiral, zigzag, armchair) and the 2D band (~2680 cm-1) shows the number of walls in the CNT. ...
Petra's user avatar
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Difference in transition lifetimes for near-resonant v/s non-resonant Raman effect

I have read that a virtual state is created when Raman scattering occurs. Since this state is forbidden, the molecule upon absorbing a photon (not enough to take it to the next electronically excited ...
user1155386's user avatar
2 votes
1 answer
3k views

Right Raman Spectrum of Cyclohexane

In this site, https://www.princetoninstruments.com/userfiles/files/assetLibrary/Technical%20posters/Poster-Aberration-Free-Raman-Spectroscopy-with-the-IsoPlane.pdf the raman spectrum of cyclohexane ...
Jtl's user avatar
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4 votes
1 answer
112 views

Could coating silver inside of a cuvette be used for SERS?

I understand that molecules adsorbed to a coinage metal surface experience plasmonic enhanced Raman shifts and I have a spectrometer that I would like to perform SERS measurements with but do not have ...
Dallon P's user avatar
0 votes
2 answers
6k views

Raman Spectrum of Water

This is the Raman spectrum of water. There is $\pu{1635 cm-1}$ Raman peak corresponding to $\ce{HOH}$ and $\pu{3410 cm-1}$ Raman peak corresponding to $\ce{OH}$. But why is there general nonzero ...
Samzun's user avatar
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1 vote
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49 views

How do blue shifts in Raman spectra indicate a co-crystalline compound?

The short conference paper The Acetylene-Butane Co-Crystal: A Potentially Abundant Molecular Mineral on Titan (mentioned in EurekaAlert's 'Bathtub rings' around Titan's lakes might be made of alien ...
uhoh's user avatar
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1 vote
0 answers
53 views

Raman Spectrum of Graphene

I recently took a raman spectrum for a sample of graphene-pla. The result had the characteristic G and D bands associated with Graphene, but not the 2D. But there is a broad peak at around 3100, which ...
user67675's user avatar
1 vote
1 answer
222 views

How to distinguish two molecules with same formula but different geometry with vibrational spectroscopy

There is a sample that we know is all made up by only one of these two molecule: how you can see they have the same formula but two different geometries. The question is if it is possible to know by ...
Landau's user avatar
  • 193
5 votes
1 answer
2k views

Raman spectra in Gaussian [closed]

I want to simulate Raman spectra of benzene in Gaussian 09. Calculated spectra for a single ring Benzene ($\ce{C6H6}$) in Gaussian differs about $\pu{40 cm^{-1}}$ for each peak, compared with ...
Persian_Gulf's user avatar
1 vote
0 answers
53 views

structure information form IR and Raman spectra? [closed]

Is it possible to gain the idea of full molecular structure from IR or Raman spectroscopy?
Bikash 's user avatar
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1 vote
0 answers
129 views

Absence of anti-Stokes line in Raman spectrum

If we have a molecule 1H-25X which shows a band at $3000~\mathrm{cm}^{-1}$ in the IR spectrum and you want to record a Stokes and anti-Stokes Raman spectrum with a laser of 1000 nm, why is the anti-...
Fechem's user avatar
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1 vote
0 answers
46 views

How on the quantum level do the notch filters used in Raman spectroscopy remove only a select wavelength of light?

From what I have gathered regarding the schematics of Raman spectrometers, the notch filter is used to remove a narrow range of light corresponding to that of the laser used to excite the sample. How ...
Joe's user avatar
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1 vote
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160 views

Raman database of polymer spectra for analyses in R/python

Can anyone reccomend a raman database of polymer spectra that is open source or freely available? I'm analyzing spectra of a number of plastics and looking for reference spectra for identification. ...
Tyler Gagne's user avatar
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27 views

Scan type of DFT calculations adding Freq=Raman keyword [duplicate]

I´m doing a scan calculation by adding Freq=Raman keyword. My objective is to obtain the Raman spectrum of each conformation in my compound. However, when i write the Freq=Raman Keyword, only the ...
S.G.V's user avatar
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4 votes
2 answers
408 views

How to obtain the Raman spectrum along every coordinate of a scan in Gaussian?

I am doing a scan calculation using Gaussian09 and adding the Freq=Raman keyword to my input file. My objective is to obtain the ...
S.G.V's user avatar
  • 79
0 votes
1 answer
245 views

Raman activity in sulfur

I was wondering why sulfur is Raman active but other elements (e.g. carbon) are not.
Paul's user avatar
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8 votes
0 answers
2k views

What drives the cost of Raman spectroscopy? [closed]

Raman spectroscopy setups are quite expensive- \$10-\$30k seems pretty common. The spectrometer, the probe/fiber cable, and the laser are typically each $3k+. The spectrometer could potentially be ...
ericksonla's user avatar
  • 1,710
1 vote
1 answer
466 views

Spectroscopy pyrazine molecule

Considering pyridazine and pyrazine molecules, I am asked to say if I can distinguish one from the other in a sample. I supposed that is possible because pyrazine belongs to D2h and so it has the ...
mickeymar's user avatar
12 votes
2 answers
748 views

Identification of Sir Raman's handheld scope

I read an article somewhere around 5-10 years ago that talked a little bit about the life of Sir C. V. Raman. The focus was on the effect of Raman spectroscopy but included an interesting little ...
Broklynite's user avatar
1 vote
2 answers
2k views

Raman Spectroscopy: How to calculate their constants?

$^1{\ce{H2}}$ is interrogated with a laser of wavelength lambda = 532 nm and vibrational Stokes transitions are observed at S(0) = 14302.206 cm$^{-1}$, Q(0) = 14638.442 and O(2) = 14992.823 cm$^{-1}$. ...
preyingmanti5's user avatar
3 votes
0 answers
3k views

How to tell if a vibrational mode in benzene is IR and/or Raman active?

Consider the vibrational mode that corresponds to the boat-like bending of a benzene ring. Is it (i) Infrared active? (ii) Raman active? This question was asked in an assignment in my college. ...
nosyminotaur's user avatar
4 votes
1 answer
568 views

Raman Spectrum of carbon chains: How to identify the vibrational modes

So I am using NWChem to calculate the raman spectra of C2H2 and C4H4. For example for the first I obtained the following frequencies: ...
user2804865's user avatar
3 votes
2 answers
6k views

Compound formed from concentrated sulfuric acid and sulfur

In the reaction below, I know what A and B are, but I'm not sure what compound C is. All I know about it is the following: Deep yellow solid Dication contains only sulfur Raman and infra-red spectra ...
Ryan White's user avatar
10 votes
1 answer
2k views

Why hydrofluoric acid (HF) has two Raman bands?

Hydrofluoric acid ($\ce{HF}$) is a diatomic molecule with only one vibrational coordinate. Therefore I would expect only one Raman band, however there are two. Why? (source)
Sparkler's user avatar
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1 vote
2 answers
6k views

Raman Spectra of Toluene

This is the raman spectra of Toluene I obtained while working at my lab using a raman spectrometer with laser of 532 nm wavelength. Well, I am a physics student, but I want to know how information ...
Roshan Shrestha's user avatar
2 votes
0 answers
122 views

SERS Gold nanoparticles performing poorly in organic solvents?

We have been working with some organic solvents lately and noticed a sharp decrease in surface-enhanced Raman spectroscopy (SERS) performance from our gold nanoparticles deposited in an organic ...
Tinker's user avatar
  • 227
5 votes
1 answer
2k views

Calculating Raman Intensities from Static Raman Activities

Whenever I want to calculate a Raman spectrum, my quantum chemical programs give me Raman scattering activities. As the common Raman spectrum is dependent on the incident wavelength of the used laser ...
pH13 - Yet another Philipp's user avatar
1 vote
0 answers
114 views

What are the strategies to deal with fluorescence from oil in Raman Spectroscopy?

I have a sample (for the purpose of this question let's call this Sample A) consisting of oil (edible olive oil) mixed with a contaminant (Contaminant B) from the Polycyclic Aromatic Hydrocarbons ...
Tinker's user avatar
  • 227
1 vote
2 answers
919 views

Why does Stokes raman not relax to the ground state while anti-Stokes does?

I'm just wondering why stoke-Raman doesn't go to the ground state. Where does the rest of energy from exciting laser leave? On the other hand, why does anti-stoke go back to ground state? I know that ...
user19568's user avatar
4 votes
1 answer
656 views

Role of Acetonitrile and Ammonium Acetate buffer in Leucomalachite Green stock solution?

I am trying to repeat an experiment conducted by FDA on Malachite Green (MG). According to this paper, ...
Tinker's user avatar
  • 227
11 votes
2 answers
9k views

Which are the differences between resonance Raman and fluorescence?

If the fluorescence is the re-emitting of a photon with a larger wavelenght due to the transition from a higher energy state to a lower energy state the case of resonance Raman (where there aren't any ...
G M's user avatar
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