Molecular hydrogen interactions with discontinuous and continuous thin gold films

The influence of thin gold film surface nanostructure on H-2 chemisorption on unsintered gold films at 78 K was studied. Three classes of thin Au film s of different thicknesses were chosen for these experiments, as follows: ( i) very thin, purplish colour, transparent film formed by isolated Au islan ds, (ii) violet-green colour film formed by Au islands joined together and creating a kind of golden net, (iii) non-transparent, continuous Au film of golden colour. It has been found that H-2 chemisorption occurs only in the case when the thin Au films are deposited at low temperatures (78 K) and u nsintered. It has been suggested that this chemisorption occurs on surface Au atoms of low coordination number as a result of formation of AuH2 comple xes, similarly to the compounds arising due to H-2 interaction with isolate d Au atoms. (C) 1999 Elsevier Science B.V. All rights reserved.