DIPOLE-MOMENT FUNCTION OF METHANE AND ANALYTICAL ANHARMONIC, 9-DIMENSIONAL POTENTIAL SURFACE - THEORY AND EXPERIMENT FOR THE PERMANENT ELECTRIC-DIPOLE MOMENT OF CH2D2 USING QUANTUM MONTE-CARLO CALCULATIONS ANDFIR SPECTROSCOPY

The pure rotational spectrum in the far-infrared and its absolute inte nsity in the vibrational ground stale of CH2D2 and CHD3 were measured by high-resolution interferometric Fourier transform techniques. The a nalysis of the integrated absorption cross sections results in a perma nent, vibrationally induced electric dipole moment \mu(0)\ = (8.6 +/- 1.4). 10(-3) Debye for CH2D2. This value is much more reliable than th e older value existing in the literature and is also in much better ag reement with our previously published theoretical estimate (mu(0)(z) = -(7.60 +/- 0.50). 10(-3) Debye, the z-axis being the C-2 axis with si gn chosen such that the H-atoms have positive z-coordinates).