Decomposition of methanethiol on Ni(111): a TPD and SSIMS study

Abstract

The adsorption and decomposition of methanethiol on Ni(111) is studied using temperature-programmed desorption (TPD), static secondary ion mass spectroscopy (SSIMS) and Auger electron spectroscopy (AES). CH 3SH adsorption is mostly molecular at 100 K. Thermal decomposition occurs below 150 K by S-H bond cleavage to form H (a) and CH 3S (a). For low thiol coverages, complete decomposition to desorbing hydrogen and residual sulfur and carbon is observed. At higher coverages, desorption of CH 4, C 2H 6 and H 2 is observed in TPD. 0.25 ML of preadsorbed sulfur inhibits thiol desulfurization and dehydrogenation. A simple mechanism that accounts for the observed results is discussed.