Collisional narrowing by polyatomic buffer gases in an optically pumped CH3F laser

The gain linewidth of an optically pumped CH3F molecular laser is observed to narrow with the addition of various polyatomic buffer gases. This is interpreted as collisional (Dicke) narrowing. The measurement is the first observation of collisional narrowing by polyatomic buffer gases. It is also the first observation of the effect in a laser oscillator. The effect was observed using a heterodyne mixing technique at the laser emission frequency of 604 GHz. Collision cross sections for SF6–CH3F and CS2–CH3F are obtained.