Surface-induced dissociation: a unique tool for studying energetics and kinetics of the gas-phase fragmentation of large ions.

Abstract

Surface-induced dissociation (SID) is a valuable tool for investigating the activation and dissociation of large ions in tandem mass spectrometry. This account summarizes key findings from studies of the energetics and mechanisms of complex ion dissociation in which SID experiments were combined with Rice-Ramsperger-Kassel-Marcus modeling of the experimental data. These studies used time- and collision-energy-resolved SID experiments and SID combined with resonant ejection of selected fragment ions on a specially designed Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Fast-ion activation by collision with a surface combined with the long and variable timescale of FT-ICR mass spectrometry is perfectly suited to studying the energetics and dynamics of complex ion dissociation in the gas phase. Modeling of time- and collision-energy-resolved SID enables the accurate determination of energy and entropy effects in the dissociation process. It has been demonstrated that entropy effects play an important role in determining the dissociation rates of both covalent and noncovalent bonds in large gaseous ions. SID studies have provided important insights on the competition between charge-directed and charge-remote fragmentation in even-electron peptide ions and the role of the charge and radical site on the energetics of the dissociation of odd-electron peptide ions. Furthermore, this work examined factors that affect the strength of noncovalent binding, as well as the competition between covalent and noncovalent bond cleavages and between proton and electron transfer in model systems. Finally, SID studies have been used to understand the factors affecting nucleation and growth of clusters in solution and in the gas phase.