Unusual hydroxyl migration in the fragmentation of β-alanine dication in the gas phase
We present a combined experimental and theoretical study of the fragmentation of doubly positively charged b-alanine molecules in the gas phase. The dissociation of the produced dicationic molecules, induced by low-energy ion collisions, is analysed by coincidence mass spectrometric techniques; the coupling with ab initio molecular dynamics simulations allows rationalisation of the experimental observations. The present strategy gives deeper insights into the chemical mechanisms of multiply charged amino acids in the gas phase. In the case of the b-alanine dication, in addition to the expected Coulomb explosion and hydrogen migration processes, we have found evidence of hydroxyl-group migration, which leads to unusual fragmentation products, such as hydroxymethyl cation, and is necessary to explain some of the observed dominant channels ; Financial support received from the CNRS PICS-05356 program, the ANR Programme Blanc PIBALE/ANR-09-BLAN-013001. Work was partially supported by the projects FIS2013-42002-R and CTQ2013-43698-P (MINECO), and NANOFRONTMAG (CAM). D.G.P. acknowledges the support of the Erasmus Mundus program of the European Union (FPA 2010-0147)
