SSL Seminar Series 2001 No. 5
Title: Making Organic Molecules on Cu(100) and GaAs(100)
Speaker: Dr NK Singh
Date: 20th February 2001, Tuesday
Time: 3:00pm
Venue: Physics Conference Room S13 M01-15

Abstract
Alkyl coupling reactions, to form longer chain hydrocarbons, form the basis of many catalysed industrial processes, eg. Fischer Tropsch reduction of carbon monoxide and Ullman synthesis of biaryls. Surface investigations carried out to date to understand the mechanisms by which carbon–carbon bonds form during the coupling process have been restricted to reactions of alkyl halides on coinage metal surfaces. Recent investigations in our group at UNSW have shown that the GaAs(100) surface is also capable of catalysing alkyl coupling reactions, which had not been appreciated previously. The intriguing aspect of the coupling reactions on this surface is that the respective alkenes form from the surface alkyl groups, whereas in the case of coinage metals long chain alkanes have always been known to form.

In this seminar coupling reactions of a number of alkanethiols and alkyl halides on GaAs(100) and Cu(100), studied by thermal desorption and X–ray photoelectron spectroscopies, will be presented. We will show that both surfaces exhibit disproportionation and coupling reactions. Mechanisms by which these occur will be discussed, and the reasons for the differences in the observed product mixtures on GaAs(100) and Cu(100) will be postulated.

About Speaker
Dr Nagindar K Singh is a Senior Lecturer in Physical Chemistry at the School of Chemistry, The University of New South Wales, Australia. After her BSc and MSc at The University of the South Pacific, Fiji, she did her PhD (1989) at the University of Nottingham, UK on "Chemisorption Studies on Single Crystal Nickel Surfaces" under an Academic Commonwealth Scholarship. She was subsequently a post-doctoral Research Fellow at the Inorganic Chemistry and Physical Chemistry Laboratories, The University of Oxford, UK before taking up her present position in UNSW. Her current areas are: (i Mechanisms of Alkyl Coupling Reactions on Metal and Semiconductor Surfaces and (ii) Growth of Titanium-based Hard Coatings from Organometallic Precursors.