Rotational state distributions of NO molecules after interaction with germanium surfaces

A. Mödi*, H. Robota, J. Segner, W. Vielhaber, Ming-Chang Lin, G. Ertl

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


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 (Ekin ≲ 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 Trot equals the surface temperature Ts, however only up to about 250 K. Further increase of Ts leads to a leveling off of Trot until a limiting value Trot,lim ≈400 K is reached. (Rotational cooling in desorption.) At higher kinetic energies direct-inelastic scattering dominates, and for E kin=820 meV a pronounced non-Boltzmann distribution (rotational rainbow) is observed. The observed effects are qualitatively interpreted in terms of current theoretical models.

Original languageEnglish
Pages (from-to)4800-4807
Number of pages8
JournalThe Journal of chemical physics
Issue number9
StatePublished - 1 Dec 1985


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