Photoionization spectra of CH3I perturbed by SF6: electron scattering in SF6 gas

A photoionization study of CH3I in the presence of SF6 perturbers (up to the perturber density 9.75×1019 cm−3) disclosed a red shift of autoionizing features that depends linearly on the perturber number density. From the perturber induced energy shifts of the CH3I nd′ Rydbergs (n=9, 10, 11, 12), the electron scattering length of SF6 was found to be A=−0.484 nm, which accords with previously reported (but less precise) cross-section data. An assessment is made of the validity of the impact approximation used in the data analysis presented here.