Collisional narrowing in the optically pumped CH3OH and CH3F lasers

The gain linewidth of the optically pumped CH
3
F laser is observed to narrow and rebroaden with the addition of He. In addition, we observe the same effect in the CH
3
OH laser with the addition of the polyatomic buffer gases SF
6
and CS
2
. These results offer conclusive evidence of the Dicke narrowing phenomena in these inverted pure rotational transitions. The effect is observed using a high harmonic mixing technique in a Schottky barrier diode.