Surface field activated fragmentation of arginine oligomers

Protonated arginine oligomers produced by matrix-assisted laser desorption/ionization (MALDI) graze at a kinetic energy of 350 eV along a surface of fluorinated hydrocarbon or mineral oil. The cation fragments activated by excitation processes during the slide on the surface are analyzed by time-of-flight mass spectrometry. The resulting fragment ion mass spectra are interpreted by applying a theoretical concept of excimol accumulation and trap bond dissociation, suggested earlier. According to this theory, energy is accumulated and fragments are formed independently by each arginine residue of a sliding oligomer ion. It is concluded that the observed variation in the fragment ion spectra of the oligomers is a consequence of different oligomer velocities and not a fingerprint of different ion structures.