Mean amplitudes of vibration of SF6 and intramolecular multiple scattering

Abstract

Precise gas phase electron diffraction data for incident electron energies of 43 and 54 keV have been collected for SF6 by counting techniques with emphasis toward a determination of root-mean-squared amplitudes of vibration and as a case study for the necessity of correcting the scattering cross sections for intramolecular multiple scattering. At first, the amplitudes and shrinkage values were found to disagree with predicted values based on spectroscopic results. However, after corrections for the multiple scattering had been applied, the values changed significantly. The new structural parameters obtained are ra (S–F) = 1.5622(7) Å, l(S–F) = 0.0416(5) Å, ra(F–F) (cis) = 2.2094(8) Å, l(F–F) = 0.0604(4) Å, ra(F–F) (trans) = 3.1240(21) Å, and l(F–F) = 0.0551(17) Å. The shrinkage values for the F–F trans distance changed from −0.0003(2) to +0.0018(2) Å due to the corrections and are now in agreement with the spectroscopic values. The success of the modified Glauber approximation warrants an introduction of this formalism into routine structure determination in electron scattering.