THE ELECTRIC-DIPOLE MOMENT OF METHYL-FLUORIDE

The Stark effect of CH3F is extensively used as a calibration standard in laser Stark spectroscopy. The accepted value for the dipole moment of the ground vibrational state of CH3F is less accurate than the precision of laser Stark measurements, and questions have also been raised about the literature value. New molecular beam spectroscopy measurements have been made of the ratio of the Stark effect in the J = 1, K = 1 and J = 2, K = 2 CH3F states to that of the 01 '0 vibrational state of OCS. The results were μ1.1(CH3F)/μ010(OCS) = 2.638905(23) and μ2.2(CH3F)/μ010(OCS) = 2.63894(10). This produces a dipole moment of 1.85840 D with precision relative to OCS of 10 ppm and absolute accuracy of 43 ppm. Copyright © 1980 by Academic Press, Inc.