Surface chemistry of the metal-halogen interface: Bromine chemisorption and dibromide formation on palladium (111) |
| |
Authors: | WT Tysoe RM Lambert |
| |
Institution: | Department of Physical Chemistry, University of Cambridge, Cambridge CB2 1EP, UK |
| |
Abstract: | At 300 K and in the coverage regime () bromine chemisorbs rapidly on Pd(111); the sticking probability and dipole moment per adatom remain constant at 0.8 ± 0.2 and 1.2 D, respectively. This stage is marked by the appearance of a √3 structure: desorption occurs exclusively as atomic Br. At higher coverages, desorption of molecular Br2 begins (desorption energy ~130 kJ mol?1) as does the nucleation and growth of PdBr2 on the surface. This latter stage is signalled by the appearance of a √2 LEED pattern and the observation of PdBr2 as a desorption product (desorption energy ~37 kJ mol?1). Some PdBr2 is also lost by surface decomposition and subsequent evaporation of atomic Br. The data indicate that the transition state to Br adatom desorption is localised and that PdBr2(a) ? Br(a) interconversion occurs; these surface species do not appear to be in thermodynamic equilibrium during the desorption process. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|