Abstraction of multiple surface atoms by pyrazine, pyrene and HC2N ions on low‐energy collisions with self‐assembled monolayer surfaces

Abstract

AbstractIon/surface reactions of pyrazine and pyrene molecular ions and the HC2N+· ion were investigated using an alkyl self‐assembled monolayer surface consisting of hydrogenated and perdeuterated chains (CH3(CH2)15S–Au and CD3(CD2)15S–Au) intimately mixed in a 1:1 ratio. Each of these projectile ions is known to react upon collision at hydrocarbon‐covered surfaces, HC2N+· by abstraction of multiple hydrogen atoms and the pyrazine and pyrene molecular ions by abstraction of groups containing one or more carbon atoms. Data from the isotopically mixed surface show that pyrazine and pyrene abstract multiple carbon units from a single chain and that the units are transferred as intact alkyl units. The isotopic peak pattern arising from addition of two hydrogens to the HC2N+· ion on collision with the mixed surface differs from that expected from random addition of H and D, and the results indicate that multiple hydrogen atoms are abstracted from the same surface chain. Translational energy measurements on the ion/surface reaction products show that they leave the surface with very low kinetic energies (<5 eV).