Abstract/Summary

Attempts to observe ΔK = ±1 transitions in the rotational spectrum of CF3CCH and CF3H in the first excited state of a degenerate vibration, by direct absorption in the Y band and K band regions of the microwave spectrum, have not been successful. In the course of this work the J = 3-2 and 4-3 rotational spectrum of CF3CCH has been observed with higher sensitivity than previously, and from the positions of the vibrational satellites several new rB values have been determined.