Angle-resolved photoelectron spectroscopy of CCl/sub 4/: The Cooper minimum in molecules

Journal Article · Wed Dec 01 04:00:00 EST 1982 · J. Chem. Phys.; (United States)

OSTI ID:6715974

Carlson, T A; Krause, M O; Grimm, F A; Keller, P; Taylor, J W

Angle-resolved photoelectron spectra have been taken for the first five orbitals in CCl/sub 4/ (2t/sub 1/, 7t/sub 2/, 2e, 6t/sub 2/, and 6a/sub 1/) using a variable photon source extracted from synchrotron radiation. From these data, the partial cross sections and angular distribution parameters ..beta.. have been determined for photon energies from 16 to 80 eV. In the case of the lone pair orbitals (2t/sub 1/, 7t/sub 2/, and 2e) minima in both the cross sections and ..beta.. values were noted experimentally in the photon energy range of 40 to 50 eV. The behavior is similar in appearance to that observed with the 3p subshell of argon and is believed to be the molecular counterpart of the Cooper minimum in atoms. Calculations of the cross sections and ..beta.. values have been made for each of the different orbitals of CCl/sub 4/ measured experimentally using the multiple scattering X..cap alpha.. theory. Agreement between theory and experiment for the lone-pair orbitals is qualitatively good and in the case of photoionization in the 2t/sub 1/ orbital it has been possible to identify which continuum channels correspond to the atomic 3s and 3d counterparts. It was also observed that the nonlone-pair orbitals (6t/sub 2/ and 6a/sub 1/) show both experimentally and theoretically shallow minima in the vicinity of photon energies where the Cooper minimum is found. Finally, experimentally determined ..beta.. values for the first three valence orbitals in CH/sub 3/Br were obtained from 20 to 50 eV. The behavior of the lone-pair orbital of CH/sub 3/ Br could be correlated with the Cooper minimum observed for the 4p orbital of Kr. The general nature of the Cooper minimum in molecules is discussed.

• Research Organization: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
• OSTI ID: 6715974
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 77:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
BREMSSTRAHLUNG
CARBON TETRACHLORIDE
CHLORINATED ALIPHATIC HYDROCARBONS
CROSS SECTIONS
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
HALOGENATED ALIPHATIC HYDROCARBONS
IONIZATION
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
RADIATIONS
SPECTROSCOPY
SYNCHROTRON RADIATION