A NEW METHOD FOR INCORPORATING MOMENTUM RESOLUTION EFFECTS AND DEFINING THE MOMENTUM SCALE IN ELECTRON MOMENTUM SPECTROSCOPY

Two existing methods for incorporating the effects of finite momentum resolution in comparing the results of electron momentum spectroscopy (EMS) experiments with quantum mechanical calculations of the electron momentum distributions are described. Neither of these existing methods is considered to be particularly satisfactory. However, a new procedure, the momentum averaged Gaussian weighted (MAGW) method, is found to be more satisfactory in the sense that it attempts to account for the acceptance angles and transmission characteristics of the ejected and scattered electrons in the EMS spectrometer in a physically more realistic manner than previous methods. A systematic error in the usual definition of the momentum scale in EMS experiments is also noted, and the MAGW method is used to correct for this error, which is appreciable at momenta below 0.4 au. Use of the new MAGW procedure, both for momentum resolution folding and defining the momentum scale, results in excellent agreement between Hartree-Fock limit theory and the measured momentum distribution for argon 3p electrons. In addition, an existing discrepancy between even the CI overlap treatment and experiment for the 1b1 orbital of H2O is effectively eliminated when the same MAGW method is used to fold the calculations and establish the momentum scale. © 1990.