Rotationally inelastic gas--surface scattering: NH/sub 3/ from NH/sub 3/-saturated W(100)
Two-photon resonant three-photon laser ionization spectroscopy is employed to study rotationally inelastic NH/sub 3/ molecular beam--surface scattering from NH/sub 3/-saturated W(100). For all surface temperatures (T/sub s/) examined (300 to 65/sup 0/K), the scattered NH/sub 3/ rotational distributions are Boltzmann-like. Complete rotational accommodation is observed for T/sub s/less than or equal to 380/sup 0/K, while for T/sub s/> 380/sup 0/K, the NH/sub 3/ rotational temperature is less than T/sub s/. Angular and velocity analysis of the scattered NH/sub 3/ for T/sub s/ = 300/sup 0/K show cosine and Maxwellian (T = 300/sup 0/K) distributions, respectively. These findings indicate a trapping--desorption scattering mechanism with a surface residence time below 10 ..mu..s at T/sub s/ = 300/sup 0/K. Scattering of a nuclear-spin-state (para) enriched NH/sub 3/ beam prepared using electric deflection techniques indicates that nuclear spin equilibration (ortho--para) is not achieved during the gas--surface encounter.
- Research Organization:
- Sandia National Laboratories, Albuquerque, New Mexico 87185
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5086446
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 85:7; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMMONIA
ANGULAR DISTRIBUTION
BEAMS
COLLISIONS
DESORPTION
DISTRIBUTION
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
HYDRIDES
HYDROGEN COMPOUNDS
INELASTIC SCATTERING
LASER SPECTROSCOPY
METALS
MOLECULAR BEAMS
MOLECULE COLLISIONS
MULTI-PHOTON PROCESSES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ROTATIONAL STATES
SCATTERING
SPECTROSCOPY
TRANSITION ELEMENTS
TRAPPING
TUNGSTEN
VELOCITY