I want to measure the temperature of an atmospheric pressure Nitrogen plasma using the Boltzmann plot method. I am unsure the process by which I should be selecting emission lines to ensure that they are optically thin. I had presumed that I should pick wavelengths which lie in the low intensity regions of the N2 emission spectrum but am unsure.

As a bit of additional information I used a set of emission data from a Mn test solution to calculate a temperature of ~5600 which is in the ball park (I expect 5000-5500). So it would seem I am on the right track but would like any advice I can get!

Please and thank you!