Temperature-Dependent Electron Momentum Spectroscopy on the Molecular Orbitals of Dimethyl Ether

This paper investigates vibrational excitation effects on valence electron momentum distributions of dimethyl ether. A symmetric noncoplanar (e, 2e) experiment has been performed for the molecule at a high temperature (980 K) as well as at room temperature (300 K). For comparison, theoretical calculations with vibrational effects being involved have also been carried out. Changes of the momentum profiles with the rise of temperature are observed for the 2b1 and 6a1 orbitals, indicating that distortion of these molecular orbitals is appreciably enhanced upon excitation of the methyl torsional vibrations. The present study provides a way for exploring the influence of vibrational excitation on electronic wavefunctions of molecules.