Questions on diatomic spectroscopy

[ollo]

I've been looking at spectra from diatomic molecules. If I know the temperature of the material I'm looking at and I know which transition I want to look at how can I calculate what the observed flux (in Jansky) should be?
Also, what can I calculate from observed FWHM?

Thanks.

[zhermes]

If I know the temperature of the material I'm looking at and I know which transition I want to look at how can I calculate what the observed flux (in Jansky) should be?
You need to solve the radiative transfer equation---in particular, finding the Einstein Coefficients (http://en.wikipedia.org/wiki/Atomic_spectral_line#The_Einstein_coefficients)


Also, what can I calculate from observed FWHM?

The width of lines tells you many things concerning the cause of Line Broadening (http://en.wikipedia.org/wiki/Spectral_line#Spectral_line_broadening_and_shift)

[ollo]

I have the Einstein coefficients and I know the relative population of states, but how do I use these to calculate a flux?