AVS 46th International Symposium
    Surface Science Division Thursday Sessions
       Session SS3+AS+NS-ThM

Paper SS3+AS+NS-ThM1
Determination of Sticking Probability and Transition State Energy by Line-of-Sight Detection: Halocarbons on Cu(111)

Thursday, October 28, 1999, 8:20 am, Room 604

Session: Novel Surface Probes & Technique Enhancement
Presenter: A.S.Y. Chan, University of Nottingham, UK
Authors: A.S.Y. Chan, University of Nottingham, UK
C.A. Clifford, University of Nottingham, UK
R.G. Jones, University of Nottingham, UK
Correspondent: Click to Email
We have used a new technique, Line-of-Sight Sticking Probability (LOSSP) to study the reactions of chloroform and 1-bromo-2-chloroethane (BCE) on Cu(111). The sticking probability measurements were made by applying a thermally randomised pressure of the halocarbon above the surface and detecting the reflected flux as a narrow beam of molecules flying in line-of-sight from the centre of the sample surface to the mass spectrometer.@footnote 1@ The general reaction undergone by both halocarbons on the copper surface is: M(gas) -> M(phys) [1] M(phys) -> M(gas) [2] M(phys) -> chemisorbed halogens + gas phase product [3]. By measuring the sticking probability as a function of temperature, we are able to obtain the energies of the transition state M(phys) towards decomposition, which for the non-activated adsorption system of BCE on Cu(111) is ~13 kJ/mol below zero, and for the activated adsorption of chloroform on Cu(111) is ~4 kJ/mol above zero. (Zero energy is defined as the energy of the molecule at an infinite distance from the surface. @FootnoteText@ @footnote 1@ R G Jones and C J Fisher; Surface Science 424 (1999)127.