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Abstract
Experimental and theoretical photo-absorption and high energy inelastic electron scattering cross sections, together with refractivity and sum rule constraints, are used to construct the non-relativistic dipole oscillator strength distribution (DOSD) for ground-state CH4. The DOSD is used to evaluate a number of useful dipole oscillator strength sums. For example, these results give the mean excitation energies (estimated error <1 per cent) associated with the Lamb shift and the stopping and straggling of fast charged particles in methane. Results are also given for all the parameters needed to evaluate the total cross section for the inelastic scattering of fast charged particles by CH4 in the Bethe-Born approximation. The DOSD is also used to evaluate the molar refractivity, as a function of wavelength, in the ultra-violet and visible spectral region, and to obtain an accurate result (estimated error <1 per cent) for the orientation averaged dipole-dipole dispersion energy constant, C 6, for the CH4-CH4 interaction. Experimental band intensities are used to evaluate the infra-red contribution to both C 6(CH4-CH4) and the dipole polarizability of methane. Finally combination rule values of C 6(CH4-B), for B=H2, N2, O2, NH3, H2O, NO, N2O and He are obtained by using C 6(CH4-CH4) and accurate literature values for C 6(B-B).
This research was supported by a grant from the National Research Council of Canada.
This research was supported by a grant from the National Research Council of Canada.
Notes
This research was supported by a grant from the National Research Council of Canada.