The valence orbital momentum distributions and binding energy spectra of dimethyl ether by electron momentum spectroscopy: An investigation of the methyl inductive effect

Abstract

The high momentum resolution experimental momentum profiles of some of the valence orbitals of (CH 3) 2O have been measured by electron momentum spectroscopy. Good agreement is obtained between the measurements and the momentum distributions calculated from relatively simple wavefunctions except in the case of the outermost 2b 1 orbital. The effects of diffuse and polarization functions in the basis sets and also the influence of molecular geometry have been investigated. The observed features of the binding energy spectra including the inner valence region are quite well reproduced by earlier published Green function calculations. Comparison of the XMPs of the outermost (HOMO and NHOMO) orbitals of H 2O, CH 3OH, and (CH 3) 2O shows an increase in low momentum components with increasing methyl substitution. The results are discussed in relation to commonly held views of the methyl inductive effect.