Showing papers by "Michael J. Brunger published in 1993"

Excitation of the electronic states of carbon monoxide by electron impact

Abstract: Differential cross sections for the electron scattering processes: X1 Sigma + to X1 Sigma +, a3 Pi , a'3 Sigma +, (d3 Delta i+e3 Sigma -+I1 Sigma -+D1 Delta ), A1 Pi , b3 Sigma +, B1 Sigma +, j3 Sigma +, (C1 Sigma ++c3 Pi ) and E1 Pi in CO have been determined for incident electron energies 20, 30, 40 and 50 eV. These differential cross sections were obtained for the scattered electron angle range 10-90 degrees by analysing electron-energy-loss spectra in CO at a number of fixed scattering angles within that range. To the best of the authors' knowledge the present study represents the first comprehensive investigation of electron impact excitation of the electronic states of CO to be thus far reported in the literature.

Electron momentum spectroscopy of the isoelectronic species hydrogen fluoride and neon

Abstract: The authors report new electron momentum spectroscopy (EMS) measurements on hydrogen fluoride (HF) and neon (Ne) at 1500 eV. The present HF data for the 1 pi , 3 sigma and 2 sigma orbitals are compared in detail with the results of an earlier EMS study at 400 and 1200 eV and with the results of a recent calculation of the valence orbital momentum distributions given by (i) SCF calculations at the Hartree-Fock limit and (ii) CI calculations of the complete molecule-ion overlap amplitude. The current Ne 2p and 2s momentum distributions are compared with the results of both the plane wave and a new, fully distorted wave Born approximation (DWBA) calculation. The results of the DWBA calculation in Ne have direct relevance to HF, in particular to the inner valence (2 sigma ) cross section.

Electron momentum spectroscopy studies on ring compounds. I. Benzene

Abstract: The complete valence shell electron separation energy spectra and momentum distributions are measured for benzene by electron momentum spectroscopy at a total energy of 1200 eV. The measured momentum distributions are compared with those calculated in the plane wave impulse approximation (PWIA) formalism using a (9s5p/4s1p) to (4s2p/2s1p) Gaussian basis set. The level of agreement between the measured momentum distributions and the PWIA-SCF orbital momentum distributions is, in general, surprisingly good, particularly given the restricted nature of the current SCF basis set. The inner valence 2e2g, 2e1u and 2a1g orbitals are severely split by final state correlation effects. The agreement between the measured and Green function many-body method calculated spectroscopic factors and separation energies is good, although the measured separation energy spectra contain significant strength up to 51 eV, this strength being mainly of 2e1u and 2a1g origin.