MICROWAVE SPECTRUM OF $METHYLPHOSPHINE^{*}$

Abstract

Some eighty rotational lines of the methylphosphine molecule have been measured in the region of 12-33 kmc. The rotational constants and dipole moment have been determined. The barrier to internal rotation of the methyl group, as determined from the A--E splittings of rotational lines in the ground torsional state and from the satellite frequency pattern of the $0_{00}\to 1_{01}$ transition, is $685.2\pm$$5 cm^{-1}$.