A number of gases are reported that extend the range of CO
2laser lines able to be modulated by means of the molecular Stark effect. Data are presented on external modulation of the

band in the

branch by methyl fluoroform and in the

branch by 1-1 difluoroethane. The gases fluoroethane, mono-methylamine, and methyl mercaptan and the vapors methanol and trichloroethylene are reported to modulate lines in the

branch of the

band.