State-resolved measurements of the energy distribution of no scattered at Ge surfaces

A673 Surface

798

STATE-RESOLVED MEASUREMENTS DISTRIBUTIONS OF NO SCATTERED F. BUDDE,

T. GRITSCH,

A. MGDL,

Science 178 (1986) 798-805 North-Holland, Amsterdam

OF THE ENERGY AT Ge SURFACES

T.J. CHUANG

* and G. ERTL

Institut ftirPh_vsrkalische Chemre, Uniuersitiil Miinchen, Sophienstrasse II, D-8000 Munich 2, Fed. Rep. of Germany

Fritz-Haber-Instrtut

der Max-Planck-Gesellschaft,

Received

1986; accepted

17 March

for publication

Farudayweg

4- 6, D-1000 Berlin 33, German.)

12 June 1986

Velocity distributions for NO( v” = 0, J”) molecules scattered from an oxidized Ge surface have been measured for various rotational states as a function of incident energy, incident angle and substrate temperature. Resonant two-photon ionization by a tunable ultraviolet laser and time-of-flight spectroscopy in combination with supersonic molecular beam-surface scattering were used for these measurements. Detailed experimental arrangements, data analyses and a brief discussion of experimental results are presented in this paper.

Surface Science 178 (1986) 806-812 North-Holland, Amsterdam

806

STICKING PROBABILITIES OF EVAPORATED ON PYROLYTIC GRAPHITE V. PHILIPPS,

E. VIETZKE

C,, C, AND C,

and K. FLASKAMP

Institut ftir Chemie I (Nuklearchemie), Kemforschungsanlage JPlich GmbH, Association Euratom KFA, D-51 70 Jiilich, Fed. Rep. of Germany Received

18 March

1986; accepted

for publication

30 April 1986

The sticking probabilities of C,, C, and C3 species evaporated on the surface of pyrolytic graphite have been determined as a function of the graphite temperature. The sticking of C,, C, and C, decreases with increasing substrate temperature reaching values of 0.5 for the C, and C, and below 0.1 for the C, component at 1800 K. The observed behaviour can be explained by reevaporation of the condensed C,, C, and C, components before a stronger bonding on special surface places occurs.