SURFACE-INDUCED DISSOCIATION FROM A LIQUID SURFACE

Mass-selected projectile ions in the tens of electronvolt energy range undergo surface-induced dissociation upon collision with a liquid per fluorinated polyether (PFPE) surface. The efficiency of translational- to-vibrational (T-V) energy transfer is similar to that observed for a fluorinated self-assembled monolayer (SAM) surface. The thermometer i on W(CO)6+. was used to determine an average T-V conversion efficiency of 18% in the collision energy range of 30-50 eV. The surface can be bombarded for several hours without displaying any change in the scatt ered ion products. Ion surface reactions occur with some projectiles a nd are analogous to those seen with the fluorinated SAM surface. For e xample, WF(square)+ (m = 1-5) and W(CO)(n)F(square)+ (n = 1-2, m = 1-2 ) are generated upon collisions of W(CO)6+. with the PFPE liquid surfa ce. The ion-surface reactions observed suggest that F atoms and/or CF3 groups are accessible for reaction while the oxygen atoms lie below t he outermost surface layover. Chemical sputtering of the liquid surfac e also occurs and yields common fluorocarbon fragment ions, including CF3+, C2F5+, and C3F7+ and the oxygenated product CFO+. The liquid sur face is remarkably free of hydrocarbon impurities. Collisions of the p yrazine and benzene molecular ions, both probes for hydrocarbon impuri ties, resulted in very little protonated pyrazine or protonated benzen e.