Time-of-flight measurements of the rotational excitation of para- and ortho-H/sub 2/ by collisions with Li/sup +/ ions. I. Angular dependent transition probabilities for the j=0. -->. 2, 2. -->. 0, 2. -->. 4, and 1. -->. 3 transitions at E/sub c. m. /=0. 6 eV
Time-of-flight spectra for the scattering of Li/sup +/ ions from para-H/sub 2/ in the j=0 and j=2 rotational states and from ortho-H/sub 2/ in the j=1 state have been measured for center of mass scattering angles between 17/sup 0/ and 50/sup 0/ at a center of mass energy of 0.6 eV. In all the spectra two or more maxima were observed. For 100 /sup 0/K para-H/sub 2/ they could be attributed to the j=0..-->..0 and j=0..-->..2 transitions. For para-H/sub 2/ at 300 /sup 0/K additional maxima due to the j=2..-->..0 and the j=2..-->..4 transitions were observed. By using normal H/sub 2/ and subtracting off the known contributions from para-H/sub 2/ the transition probability for the j=1..-->..3 transition was also obtained. The angular resolution was sufficient to resolve the ''fast'' undulations as well as the rainbow maximum for both the j=0..-->..0 and j=0..-->..2 transitions. The results are compared directly with differential cross sections calculated by Schaefer and Lester (J. Chem. Phys. 62, 1913 (1975)) using a close coupling procedure with the inclusion of a number of closed channels for the best ab initio CI-type potential hypersurface. The comparison reveals a noticeable discrepancy in the angular location of the rainbow. This difference suggests that the ab initio potential well is too shallow in the experimentally probed region by about 17% to 35%.
- Research Organization:
- Max-Planck-Institut fuer Stroemungsforschung, Boettinger-Str. 4-8, D-3400 Goettingen, Federal Republic of Germany
- OSTI ID:
- 5867311
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 71:9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROGEN
ION-MOLECULE COLLISIONS
EXCITATION
LITHIUM IONS
ENERGY-LEVEL TRANSITIONS
ROTATIONAL STATES
TIME-OF-FLIGHT METHOD
ATOMIC IONS
CHARGED PARTICLES
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
ION COLLISIONS
IONS
MOLECULE COLLISIONS
NONMETALS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena