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Nature of high CF/sub 4/ vibrational levels excited by proton energy loss spectroscopy

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:6097841

The forced harmonic oscillator model, which has been applied to proton energy loss spectroscopy (PELS), is extended here to probe the nature of CF/sub 4/ vibrational levels excited by the proton beam. At each overtone of the triply degenerate ..nu../sub 3/ vibration, there is a collection of vibrational sublevels which differ in the way amplitude is distributed among the four C--F bonds. The model predicts that PELS populates a broad distribution of these sublevels with a propensity for the highest energy, most delocalized vibrations in each overtone band. Comparison is made with infrared multiphoton absorption which excites delocalized vibrations in SF/sub 6/ and with single photon overtone absorption which selects the most localized states. Peak positions in a simulated spectrum match the experiment up to 8..nu../sub 3/ but for higher overtones the anharmonic shift is up to 0.05 eV less than observed. A demanding test of the model must wait for higher resolution experiments and better spectroscopic constants.

Research Organization:
Department of Chemistry, University of Rochester, Rochester, New York 14627
OSTI ID:
6097841
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 84:8; ISSN JCPSA
Country of Publication:
United States
Language:
English