PNNL

Abstract

Achieving a fundamental understanding of the mechanism of unimolecular dissociation of internally excited complex molecules is one of the most important challenges in modern mass spectrometry. One of the central questions is whether the dissociation of large molecules is properly described by statistical theories—RRKM/QET or Phase Space Theories —that have proved to be remarkably successful both for small molecules and a number of small and medium size peptides. The concept question is whether the ergodic assumption that the internal excitation of the ion is randomly redistributed among the vibrational degrees of freedom prior to fragmentation is satisfied for large molecules. The validity of the ergodic hypothesis for dissociation of gas-phase biomolecules has been recently reviewed and will be only briefly discussed here.