Electron momentum spectroscopy study of outer valence electronic structure of pyrrole

The binding energy spectrum and electron momentum distributions (EMDs) for the outer valence shells of pyrrole molecule are measured by a high-sensitivity (e, 2e) spectrometer at incident energy of 1200 eV plus the binding energy employing non-coplanar symmetric kinematic geometry. The obtained EMDs are compared with the theoretical calculations at equilibrium molecular geometry as well as considering vibrational effect by density functional theory method. The result shows that the molecular vibrational motion has obvious influence on EMDs for some of the outer valence orbitals. The controversy over the assignment of the ionization bands, especially the positions of satellite states concerning the ionization of 1b1 orbital, in the binding energy range of 11-16.5 eV has been clarified.