Why do I plot certain Raman against the wavenumber

In summary, when conducting Raman spectroscopy measurements, the intensity is plotted against the Raman shift for 785 nm laser measurements, but for measurements involving a 532 nm laser, the program Spectrasuite is used to display the intensity against the "normal" wavenumber. This is because wavenumber is more natural for measuring spectra as it is proportional to energy. Additionally, it is common to measure and average the spectrum multiple times to reduce random errors and noise. The bonus question discusses why multiple spectra (in this case 13) are measured and averaged.
  • #1
metorido
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I am currently writing my Bachelorthesis about Raman spectroscopy. For measurement with a 785 nm Laser I plot the Intensity against the Raman shift. But for measurements involving a 532 nm, I had so select the program (Spectrasuite) so display them against the "normal" wavenumber. Why is that?

Thank you all in advance, really desperate here.

Bonus question: Why do I measure a certain amount ( in my case 13) of spectra?
 
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  • #2
Wavevenumber is proportional to energy, so it is more natural to measure spectra in wavenumber instead of wavelength. Theory gives the energy levels and and absorption/emission is proportional to the difference of the energies between the levels the transition occurs.

It is usual to measure something (the spectrum for example) several times, and average. The random errors, the noise of the spectrum diminishes this way.
 
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FAQ: Why do I plot certain Raman against the wavenumber

Why do I plot certain Raman against the wavenumber?

1. What is the purpose of plotting Raman against the wavenumber?

The purpose of plotting Raman against the wavenumber is to visualize the vibrational modes of a molecule. The wavenumber represents the energy of each vibrational mode, and the Raman scattering intensity is proportional to the strength of the vibrational mode.

2. How does the wavenumber affect the Raman signal?

The wavenumber directly affects the Raman signal as it represents the energy of each vibrational mode. As the wavenumber increases, the energy of the vibrational mode increases, resulting in a higher Raman scattering intensity.

3. What information can be obtained from plotting Raman against the wavenumber?

Plotting Raman against the wavenumber can provide information about the molecular structure and chemical bonds present in a sample. It can also identify the functional groups and their relative concentrations in a molecule.

4. Why is the wavenumber scale used instead of wavelength in Raman spectroscopy?

The wavenumber scale is used in Raman spectroscopy because it is directly proportional to the energy of the vibrational mode, making it easier to interpret and compare Raman spectra. Additionally, the wavenumber scale is more precise and has a larger dynamic range compared to the wavelength scale.

5. Can Raman spectra be compared if they are plotted against different wavenumber ranges?

Yes, Raman spectra can be compared if they are plotted against different wavenumber ranges. The relative positions and intensities of the peaks will remain the same, but the scale of the wavenumber axis may be different. However, it is important to note the range of the wavenumber axis when comparing spectra to ensure accurate interpretation.

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