Charge transfer and structured vibrational distributions in H/sup +/+CH/sub 4/ low-energy collisions

Journal Article · Wed Jun 01 04:00:00 EDT 1988 · J. Chem. Phys.; (United States)

OSTI ID:5228537

Chiu, Y; Friedrich, B; Maring, W; Niedner, G; Noll, M; Toennies, J P

Inelastic and charge transfer collisions of protons with methane molecules have been investigated in a perpendicular-plane crossed beam experiment via the detection of the scattered protons and H atoms, respectively. Time-of-flight analysis of the protons and H atoms at scattering angles 0/sup 0/less than or equal tothetaless than or equal to10/sup 0/ and collision energies 10less than or equal toEless than or equal to30 eV provided information on internal energy distributions of the CH/sub 4/ and CH/sup +//sub 4/ products. Excitation of the n(..nu../sub 1/ ,..nu../sub 3/) +m (..nu../sub 2/ ,..nu../sub 4/) type vibrations, with n,m = 0, 1, 2,xxxwas found to be the most probable assignment of the observed structured energy distributions of CH/sub 4/ (/sup 1/ A/sub 1/ ) at thetaless than or equal to4/sup 0/. At theta>4/sup 0/, the energy transfer increases steeply up to the dissociation limit while the vibrational structure was no longer resolved. In the case of charge transfer, the observed narrow internal energy distributions corresponding to a most probable average internal energy of CH/sup +//sub 4/ of about 0.95 eV was centered at the recombination energy of the proton indicative of quasiresonant charge transfer. In addition, fragmentation of CH/sup +//sub 4/ formed in charge transfer collisions of H/sup +/ with CH/sub 4/ was investigated in an independent experiment using mass spectrometric analysis to identify the individual fragment species. The relative intensities of the parent and fragment ions (i.e., of CH/sup +//sub 4/, CH/sup +//sub 3/, and CH/sup +//sub 2/) were found to be in good agreement with the known values of the appearance potentials of the fragment ions and the distribution of the CH/sup +//sub 4/ internal energy as obtained from the differential cross sections.

• Research Organization: Max-Planck-Institut fuer Stroemungsforschung, D-3400 Goettingen, Federal Republic of Germany
• OSTI ID: 5228537
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 88:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKANES
BEAMS
CATIONS
CHARGE EXCHANGE
CHARGED PARTICLES
COLLISIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
DISTRIBUTION
ENERGY LEVELS
ENERGY RANGE
ENERGY TRANSFER
ENERGY-LEVEL DENSITY
EV RANGE
EV RANGE 10-100
EXCITED STATES
HYDROCARBONS
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONS
METHANE
MOLECULAR BEAMS
MOLECULE COLLISIONS
ORGANIC COMPOUNDS
VIBRATIONAL STATES