Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths. X. The Spectrum of Tri-Deuteromethane in the Photographic Infrared

The absorption spectrum of CD3H has been investigated under high resolution in the photographic infrared with absorbing paths of up to 7 m atmos obtained by multiple reflection. Two simple parallel bands were observed at 8870A and 11590A. The K structure in the former was clearly resolved. The rotational structure of the two bands was analyzed yielding B0=3.2787±0.0010 cm−1.On the assumption of tetrahedral symmetry for the CD3H molecule this value leads to a C–H distance r0=(1.09193±0.00017)×10−8 cm.This value is compared with the corresponding values obtained by other authors from studies of CH4 and CH3D.