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Time-of-flight measurements of high-overtone mode-selective vibrational excitation of CH/sub 4/, CF/sub 4/, and SF/sub 6/ in collisions with H/sup +/, D/sup +/ and Li/sup +/ ions at energies between 4 and 10 eV

Conference · · J. Phys. Chem.; (United States)
OSTI ID:6557481
; ; ;

Time-of-flight spectra have been measured for the scattering of H/sup +/, D/sup +/, and Li/sup +/ ions from the spherical molecules CH/sub 4/, CF/sub 4/, and SF/sub 6/ at center-of-mass angles between 3 and 30/sup 0/. At angles up to about 15/sup 0/ all the spectra show multiple peaks, which are especially well resolved in the H/sup +/ and D/sup +/ experiments. The observed maxima have been attributed to the overtone excitation of a single vibrational mode with vibrational quanta up to eta = 7 in the case of CF/sub 4/ and SF/sub 6/, whereas the CH/sub 4/ spectra reveal multimode excitation. In all cases the peak locations can be fitted by assuming no rotational excitation consistent with the near-perfect spherical symmetry of the molecules. In H/sup +/(D/sup +/)-CF/sub 4/ and H/sup +/(D/sup +/)-SF/sub 6/ the nu/sub 3/ mode is excited at 10 eV. For Li/sup +/-CF/sub 4/ the nu/sub 2/ mode is excited at low energies (approx. = 4 eV), whereas the nu/sub 3/ mode is excited at 10 eV. In Li/sup +/-SF/sub 6/ the structure is consistent with the nu/sub 2/ or nu/sub 4/ modes and is probably due to the nu/sub 4/ mode. The relative transition probabilities in most cases follow a Poisson distribution, implying that the excitation can be attributed to a long-range electrostatic linear coupling to a harmonic oscillator.

Research Organization:
Max-Planck-Institut fuer Stroemungsforschung, Goettingen, Germany
OSTI ID:
6557481
Report Number(s):
CONF-8106216-
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:7; ISSN JPCHA
Country of Publication:
United States
Language:
English

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Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKANES
CARBON TETRAFLUORIDE
CHARGED PARTICLES
CHEMICAL ANALYSIS
COLLISIONS
DATA
DEUTERIUM IONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
EXPERIMENTAL DATA
FLUORIDES
FLUORINATED ALIPHATIC HYDROCARBONS
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
HYDROGEN IONS
INFORMATION
ION COLLISIONS
ION SCATTERING ANALYSIS
ION-MOLECULE COLLISIONS
IONS
LITHIUM IONS
METHANE
MOLECULE COLLISIONS
NONDESTRUCTIVE ANALYSIS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
SCATTERING
SPECTRA
SULFUR COMPOUNDS
SULFUR FLUORIDES
TIME-OF-FLIGHT METHOD
VIBRATIONAL STATES