Metastable-Atom-Induced Dissociation of Dodecanethiolate Self-Assembled Monolayers on Gold Substrates

摘要

Emission of H~+ and CH_x~+ is observed for dodecanethiolate SAMs on Au(111) surfaces under irradiation of the slow helium metastable atom beam at a thermal energy. Metastable atom deexcitation spectroscopy measurements show that impinging metastable helium atoms predominantly interact with σ_p orbitals constituted mainly of carbon 2p and hydrogen 1s atomic states of the methyl group at the top end of the alkane chain of the dodecanethiolate molecule. These results indicate that the hole created in the σ_p orbitals leads not only to C-H bond scission followed by H~+ desorption but also to C-C bond scission between the methyl group and the neighboring carbon atom followed by CH_x~+ desorption.