Emission Spectra of Pulsed Chemical Lasers

There is a large number of chemical laser publications that deal with the investigation of the output spectra, mostly in a rather empirical fashion. The two questions which may be answered qualitatively concern the identification of the pumping reaction and the confirmation of predictions for the output composition. Such predictions may be based on spontaneous infrared luminescence measurements. 

By investigating the vibrational transitions present in the laser signal, the contribution of the hot reaction  

Chemical-laser emission spectra up to 1967 have been compiled by Patel 6 ). There is some inconsistency between HF laser spectra obtained in different laboratories and with different experimental set-ups. This is probably due in part to the absorption of several HF lines by the atmosphere inside or outside the laser cavity. However, there is additional inconsistency between the emission spectra of infrared chemiluminescence experiments and HF chemical lasers. While spontaneous luminescence predicts a peak in the v=2 - 1 transitions around /=614 , the laser emission usually 

Note added in proof More detailed investigations which have been conducted in the meantime indicate a stronger contribution from the hot reaction now (S. Suchard, private communication). 

A tentative interpretation of these results may be based on the assumption that in this laser high rotational levels (J 10) are indeed populated initially 71 . It should also be mentioned that two peaks in the rotational energy distribution are similarly observed in HC1 chemiluminescence experiments under conditions of partial rotational relaxation 9 . A simple rotational relaxation model suggested by Polanyi and Woodall 72) has been applied to fit these observations. In this model the probability P of the relaxation process J + AJ) / is given as 

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