Rotational state distributions of NO molecules after interaction with germanium surfaces

Journal Article · Fri Nov 01 04:00:00 EST 1985 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.449006· OSTI ID:5174174

Moedl, A; Robota, H; Segner, J; Vielhaber, W; Lin, M C; Ertl, G

The rotational state distributions of NO molecules scattered at clean and oxidized Ge surfaces were determined by means of laser induced fluorescence (LIF). For low incident kinetic energies (E/sub kin/< or approx. =200 meV) scattering is dominated by trapping/desorption and the molecules coming off the surface are translationally accommodated to the surface temperature. The rotational state populations can in this case be approximated by a Boltzmann distribution. The rotational temperature T/sub rot/ equals the surface temperature T/sub s/, however only up to about 250 K. Further increase of T/sub s/ leads to a leveling off of T/sub rot/ until a limiting value T/sub rot,lim/roughly-equal400 K is reached. (Rotational cooling in desorption.) At higher kinetic energies direct-inelastic scattering dominates, and for E/sub kin/ = 820 meV a pronounced non-Boltzmann distribution (rotational rainbow) is observed. The observed effects are qualitatively interpreted in terms of current theoretical models.

• Research Organization: Institut fuer Physikalische Chemie, Universitaet Muenchen, 8000 Muenchen 2, West Germany
• OSTI ID: 5174174
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 83:9; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640301* -- Atomic
Molecular &amp; Chemical Physics-- Beams &amp; their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAMS
CHALCOGENIDES
COLLISIONS
DISTRIBUTION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
GERMANIUM
METALS
MOLECULAR BEAMS
MOLECULE COLLISIONS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
ROTATIONAL STATES
SURFACES