In situ observation of particle-induced desorption from a self- assembled monolayer by laser-ionization mass spectrometry

We studied particle-stimulated desorption processes of highly ordered, self-assembled monolayers of biphenyl-based thiols covalently bound to Au/mica substrates with laser postionization in combination with mass spectrometry. Direct evidence was obtained that large molecular fragments are removed from these monolayers during impact of electrons with a kinetic energy of 1 keV. The damage that accumulates in the self-assembled monolayer with increasing electron dose was measured using ion-beam, sputter-initiated laser probing. Our results show that electron-induced desorption competes with the gradual erosion of the monolayer by the formation of a carbonaceous residual layer on the substrate. (C) 2003 American Institute of Physics.