ADSORPTION AND REACTION OF METHANETHIOL ON W(001)

Methanethiol (CH3SH) adsorbs dissociatively on W(001) at 100 K, forming two distinct intermediates. These species have been identified by S 2p soft X-ray photoelectron spectroscopy (SXPS) as methyl thiolate moieties adsorbed in different bonding sites. Both species are stable at all coverages up to 150 K. At low coverages the thiolates totally decompose upon heating into atomic C and S and gaseous H-2. At high coverages a competing pathway produces atomic S and gaseous CH4. The thiolate adsorbed in a fourfold hollow site undergoes C-S bond scission at a lower temperature than the species in a lower coordination site. At high coverage the fourfold bonded intermediate preferentially leads to total decomposition whereas the other species favors methane formation.