Izvestiya Akademii Nauk SSSR. Seriya Fizicheskaya vol:66 issue:7 pages:1012-1015
The ion-stimulated desorption of molecular fragments from self-assembled monolayers (SAMs) composed from phenethyl mercaptan (PEM) C6H5CH2CH2-SH and 2-(4'-methyl-biphenyl-4yl)-ethanethiol (BP2) CH3C6H4C6H4CH2CH2-SH deposited on Au(111) substrate was investigated. The emission of neutral fragments was measured by laser postionization mass spectrometry. From experimentally obtained time-of-flight (TOF) distributions, it was determined that the majority of ion-desorbed neutral molecules leave the surface with very low translational energies. As-the sample temperature is reduced, the distributions become broader and shift to longer flight times. The shift is the most pronounced for molecules emitted from BP2 and increases with the size of the recorded molecular fragment. The time dependence of neutral desorption signal shows that the damage cross section is large and exceeds the damage cross section reported for electron-irradiated samples by orders of magnitude.