Public Lab Research note


Absorption lines in flare spectra

by warren | October 09, 2013 20:10 | 50 views | 0 comments | #9431 | 50 views | 0 comments | #9431 09 Oct 20:10

What I want to do

There seem to be some distinct lines missing in the Chalmette flare spectra folks have been collecting. There's a separate post on emission spectra in these, which is the primary goal; this is more of a speculative exploration on if we can also measure absorption lines since the flame is a good full-spectrum light source and the steamy/smoky stuff coming out might allow us to detect some molecules. Emission spectra are mostly just for atoms, not full molecules, so this would be a nice secondary technique.

Here's a great example of an atmospheric spectrum (of the sky):

https://spectralworkbench.org/analyze/spectrum/913 (see below)

sky.png

My attempt and results

Since we're not sure Scott's spectrometer is well calibrated, I tried to align the spectra visually using the green band as a reference. I compared it to another spectrum from a Desktop kit, so the scale should be similar.

capture-2.png

Top, a Chalmette flare spectrum from July 27. Bottom, a sky spectrum from Moscow, showing a nice oxygen absorption line at ~760nm

It seems to me that the faint line in the flare spectrum aligns with the ~760nm O2 line in the sky spectrum. Since that's a particularly strong absorption line (see this annotated one by Liz), that seems feasible.

Questions and next steps

If we can identify some other absorption lines, and clean up the data a bit, we might be able to fingerprint other whole molecules.

We should also try to figure out what the big missing region (big dip) in the red part of the spectrum is -- I don't think any absorption lines are that wide, so what's going on there (below)?

capture-3.png


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