AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP18
Adsorption, Decomposition and Stabilisation of 1,2-dibromoethane on Cu(111)

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: A.S.Y. Chan, University of Nottingham, UK
Authors: A.S.Y. Chan, University of Nottingham, UK
R.G. Jones, University of Nottingham, UK
Correspondent: Click to Email
The molecular adsorption and thermal reaction of 1,2-dibromoethane (DBE) on Cu(111) has been studied using Ultraviolet Photoelectron Spectroscopy (UPS), work function change (@Delta@@Phi@) measurements, Low Energy Electron Diffraction (LEED) and Line-of-sight Temperature Programmed Desorption (LOSTPD). At 100 K, DBE adsorbs molecularly, exhibiting a decrease in work function of 0.86 eV at the completion of the monolayer. Layer-by-layer growth is observed up to two molecular layers, with further adsorption leading to the growth of tower crystallites. The first layer of DBE undergoes thermal decomposition at 120 K to give gaseous ethene and chemisorbed bromine in a (@sr@3x@sr@3)R30° structure, which increases the work function of the surface by 0.58 eV. Chemisorbed bromine from partial decomposition of the first layer is found to stabilise the remaining DBE molecules in the decomposing layer, thereby arresting complete decomposition until a higher temperature, leading to the emission of ethene at 140 K and 160 K for decomposition of the surface DBE layer in the submonolayer and multilayer regime respectively. The possibility of the ethene product being stabilised by co-adsorption adjacent to the chemisorbed bromine is discussed.