Spectra: line mixing explanation?

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Discussion Overview

The discussion centers around the concept of line mixing or cross-relaxation in atomic and molecular spectra. Participants seek a clear conceptual explanation of why two transitions might mix and the conditions under which this phenomenon occurs, with a focus on modeling spectra as the sum of individual transition shapes.

Discussion Character

  • Exploratory, Conceptual clarification, Technical explanation

Main Points Raised

  • One participant requests resources for understanding line mixing and its conceptual basis.
  • Another participant suggests that the original poster might be referring to phenomena like Fermi resonance, indicating a specific example that could be relevant.
  • A later reply expresses interest in modeling spectra as independent contributions from individual transitions and seeks to identify phenomena that could lead to inaccuracies in this model, particularly interference between lines.

Areas of Agreement / Disagreement

The discussion remains unresolved, with participants exploring different aspects of line mixing and its implications without reaching consensus on specific definitions or models.

Contextual Notes

Participants have not fully defined the assumptions or conditions under which line mixing occurs, and there is a reliance on specific examples like Fermi resonance that may not encompass the broader topic.

mikeph
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Hi

Can anyone point me to a clear description of line mixing/"cross-relaxation" in atomic/molecular spectra?

Every paper I read assumes some previous knowledge, is there an online resource that will explain why two transition would mix? I'm specifically looking for conceptual explanation and conditions for this phenomenon to occur.

Thanks
Mike
 
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can I bump this?
 
That looks similar to what I'm thinking of. In general I want to model a spectrum as the addition of individual transition shapes, i.e. I'm treating each line as an independent contributor to the overall spectrum. I'm looking for any phenomenon which will make this model inaccurate, like any type of interference between lines.

I'll have a read around Fermi resonances because the CO2 example seems quite relevant. Thanks!
 

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