COTTON MOUTON EFFECTS, MAGNETIC HYPERPOLARIZABILITIES, AND MAGNETIC ANISOTROPIES OF THE METHYL HALIDES - COMPARISON WITH MOLECULAR ZEEMAN AND HIGH-FIELD NMR SPECTROSCOPIC RESULTS

Measurements of the vapor-phase Cotton-Mouton effects of methyl fluoride, methyl bromide, and methyl iodide are reported. Analysis of the results, in conjunction with those of an earlier study of methane and methyl chloride, shows that in the series CH3X (X = H, F, Cl, Br, I) the magnetic hyperpolarizability anisotropy, which is related to the quadratic response of the molecular polarizability to a magnetic field, is positive in sign and roughly proportional in magnitude to the mean polarizability. The magnetic anisotropies (10(29) DELTA-X/J T-2) found for methyl chloride, methyl bromide, and methyl iodide (CH3Cl, -15.0 +/- 1.3; CH3Br, -15.1 +/- 0.8; Ch3I, -18.0 +/- 1.5) are compared with values obtained by the molecular Zeeman and high-field H-2 NMR spectroscopic methods.