Study of the HF chemical laser by pulse-delay measurements

A simple analytical model is presented to describe the delay τ
c
between flashlamp initiation and laser-pulse onset in the flash-photolysis HF chemical laser. The predictions of the model agree well with experiments concerning the functional dependence of τ
c
on pressure, flashlamp intensity, optical cavity loss, and the absolute magnitude of τ
c
. This detailed agreement between theory and laser performance has not been achieved in previous chemical laser work. The pulse-delay measurements demonstrate the presence of complete vibrational inversion at the time of laser-pulse initiation. In the Appendixes, the fractional photodissociation of MoF
6
is calculated for the experimental geometry used, the effects of flashlamp heating are considered, and a general expression for the temperature dependence of HF laser gain is derived and plotted. A complete bibliography of laser transitions in HF and DF is included.