# Relative intensity changing with temperature?

1. Aug 1, 2008

### AdrianH

I am trying to determine the temperature in a discharge lamp. I have the spectrum of that lamp and Nist Atomic Spectra Database. I don't have the pressure in the lamp (can I determine that too? How?). The spectrum that I have has a low resolution (of about 0.3 nm). Can this be done?
1) One method that I know is to compare 2 distinct lines that represent the transitions from one energy level to two fairly different energy levels or transitions from two different levels to a single level (am I wrong?).
2) Checking the broadening and the self-absorbtion of a line (assuming that the pressure is sufficient), but I don't know much about this. Can someone explain this technique or point me to the literature (would the resolution be enough for this?)

(sorry for my english, I'm romanian)

2. Aug 2, 2008

### Andy Resnick

The problem is that discharge lamps don't have a blackbody spectrum (or even a close approximation), so determining a thermodynamic temperature is problematic.

There are numerous ways to assign a temperature based on the relationship between your lamp output and that of a blackbody radiator (effective temperature, etc.)

The broading of the line could probably give you a pressure measurement- look up "homogeneous line broadening", but I would be surprised if the number was significantly different than the manufacturer spec.

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