Measurements of the valence shell binding energy spectrum and momentum profiles of the frontier orbitals of propane by binary (e,2 e) spectroscopy

We report here the first measurements of the momentum distributions for the frontier orbitals of propane (C3H8) using a high-resolution binary (e,2e) electron momentum spectrometer, at an impact energy of 1200 eV plus the binding energy and using symmetric non-coplanar kinematics. Binding energy spectra of the complete valence shell are obtained at a coincidence energy resolution of 0.9 eV FWHM. The binding energies are in excellent agreement with photoelectron spectroscopy data. The experimental momentum profile is compared with the summed calculated momentum distribution for the three individual frontier orbitals. The experimental measurement is well described by Hartree-Fock and density functional theory (DFT) calculations using a large basis set. (C) 1999 Elsevier Science B.V. All rights reserved.