A 1 7 0

Surface Science 127 (1983) 283-314 283 North-Holland Pubhsbang Company

R O T A T I O N A L L Y M E D I A T E D S E L E C T I V E A D S O R P T I O N I N R I G I D

R O T O R / R I G I D S U R F A C E S C A T T E R I N G

R e m h a r d S C H I N K E

Max-Planck-Instttut fur Stromungsforschung, D-3400 Gottmgen, Fed. Rep of Germany Received 21 October 1982, accepted for pubhcattOn 16 December 1982

We present a detmled mvesUgatlon of a new effect m molecule/surface scattering, rotatlonally medmted selective adsorption, whach has been first observed by Cowm et al (J Chem Phys 75 (1981) 1033) m rotatlonally inelastic H D / P t (1 l l ) scattering I t as due to resonance between an asymptotically closed rotational channel and a vabratlonal bound state of the molecule/surface system Exact close-coupling and dfffractlonally sudden calculations are performed for HD scattered from a rigid, flat and weakly corrugated surface Both variation of the colhsion energy and variation of the mcldent angle are considered In the latter case we mchade the averaging over the colhslon energy of the tmtlal beam and compare quahtatwely our results with the expermaent Taking into account the resonances below t he j = 0 ~ 1 threshold we are able to explmn all of the experimentally observed resonances and to assign them wath the appropriate rotational-vibrational quan tum numbers The largest devtatlon between experimental and theoretical resonance angles is

- 1 6 ° at a colhslon energy of E = 109 meV An interesting interference effect is found m the case of weak surface corrugation Although the dfffractlonally sudden approxamatlon generally gwes only poor results, ~t also reproduces thas effect and provides a simple explanation of It m terms of the Brelt-W~gner representation of the S-matrix

Surface Science 127 (1983) 315-330 315 North-Holland Pubhshmg Company

T H E E F F E C T O F O X Y G E N O N T H E S P U T T E R I N G O F M E T A S T A B L E

A T O M S A N D I O N S F R O M B a M E T A L *

D G R I S C H K O W S K Y , M m g L . Y U a n d A C . B A L A N T

IBM Thomas J Watson Research Center, P 0 Box 218, Yorktown Hetghts, New York 10598, USA

Received 9 November 1982, accepted for pubhcatlon 5 January 1983

By means of the Doppler-Shaft-Laser-Fhaorescence techmque we have measured the effect of oxygen coverage on the velocity &stnbut~ons and relattve yields of sputtered Ba atoms and ions m both the ground and metastable excited states Our measurements show no evidence that the excitation probabdmes are correlated with the magnitude of the electnc-&pole-moment matrix element to the ground state We also fred that the excitation probabdity of the Ba( 1 D) state from a clean metal surface depends strongly on the enusslon velocity v and approaches the functional form e x p ( - A/av ) at higher velocmes