Raman Spectroscopy: Why Peaks of Stokes Higher than Anti-Stokes?

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Discussion Overview

The discussion revolves around the observation that Stokes peaks are higher than anti-Stokes peaks in Raman spectroscopy, focusing on the underlying reasons for this phenomenon. The scope includes conceptual understanding of Raman scattering and the population of electronic states involved.

Discussion Character

  • Conceptual clarification, Technical explanation

Main Points Raised

  • Some participants propose that the difference in peak heights is due to the nature of the initial states involved in Stokes and anti-Stokes processes.
  • One participant suggests that anti-Stokes scattering occurs from an excited state, leading to a lower population of electrons in that state compared to the ground state, which may explain the lower intensity of anti-Stokes peaks.
  • Another participant reiterates the idea that the population of electrons in the excited state is lower than in the ground state, implying this contributes to the observed peak intensity differences.

Areas of Agreement / Disagreement

Participants generally agree on the explanation that the population of electrons in excited states is lower than in ground states, which may account for the differences in peak heights. However, the discussion does not reach a consensus on the completeness or implications of this explanation.

Contextual Notes

The discussion does not address potential limitations or assumptions regarding the population distributions of electronic states or the specific conditions under which the Raman spectra are measured.

fricke
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Why do peaks of Stokes higher than peaks of anti-Stokes in graph of absorbance unit against wave number?
 
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Because anti-Stokes typically takes place when the initial state is an excited state.
 
blue_leaf77 said:
Because anti-Stokes typically takes place when the initial state is an excited state.
Thank you for your reply!
So, anti-Stokes has lower peaks than Stokes because its initial state is an excited state where the population of electrons at excited state is lower than the ground state? Does it make sense?
 
fricke said:
Thank you for your reply!
So, anti-Stokes has lower peaks than Stokes because its initial state is an excited state where the population of electrons at excited state is lower than the grounded state? Does it make sense?
Basically yes.
 

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