Electron impact study of the 50 000 cm/sup -1/ band of benzene
The 5.7--6.7 eV energy loss region of the electron scattering spectrum of benzene which contains the 50 000 cm/sup -1/ (2100 A) optical absorption band has been studied with incident energies from 10 to 42 eV, scattering angles from 0/sup 0/ to 15/sup 0/, and energy resolution from 25 to 35 meV. Three different inelastic processes have been detected including the S/sub 2/ /sup 1/B/sub 1u/reverse arrowS/sub o/ transition whose diffuse vibronic bands extend from 6.0 to 6.7 eV, a process at 6.31 eV which occurs strongly at incident energies above 20 eV and increases in intensity relative to the rest of the spectrum with increasing scattering angle and a weak, featureless process below the onset of the S/sub 2/reverse arrowS/sub o/ transition starting at 5.67 eV. Aside from the weak process below the onset of the S/sub 2/ state and a singlet--triplet transition observed at very low impact energy, the electron impact spectrum at incident energies below 20 eV and scattering angles to 15/sup 0/ agrees completely with the optical absorption spectrum. The 6.31 eV process arises from a second electronic state at this energy which causes the apparent shift in vibronic band intensities with scattering angle of the S/sub 2/reverse arrowS/sub o/ transition first observed by Lassettre et al. The state responsible for this effect is shown to be the same state observed in two photon absorption by Johnson and assigned as /sup 1/E/sub 1g/ or /sup 1/E/sub 2g/. Neither the 6.31 eV process nor any energy-shifted analog of it is observed in toluene: providing additional evidence that the 6.31 eV state is a Rydberg state.
- Research Organization:
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218
- OSTI ID:
- 6151672
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71:1; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AROMATICS
BENZENE
COLLISIONS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELECTRONIC STRUCTURE
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EV RANGE 10-100
HYDROCARBONS
INELASTIC SCATTERING
MOLECULE COLLISIONS
ORGANIC COMPOUNDS
SCATTERING
SPECTRA
ULTRAVIOLET SPECTRA