Suchergebnisse

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)

TCNQ derivatives adsorbed on a metal surface undergo a self-limited decyanation reaction that only affects two out of the four cyano groups in the molecule. Combined Scanning Tunneling Microscopy/X-ray Photoelectron Spectroscopy experiments and Density Functional Theory calculations relate the self-limiting behavior to the transfer of electrons from the metal to the molecule ; We thank the CCC-UAM and the RES for allocation of computer time. Our work has been supported by the MINECO of Spain (MAT2009-13488, FIS2010-18847, FIS2010-15127, FIS2012-33011, CTQ2010-17006, CTQ2011-24652/BTQ), Comunidad de Madrid (Nanobiomagnet S2009/MAT-1726, Madrisolar-2 S2009/PPQ-1533), CONSOLIDER-INGENIO on Molecular Nanoscience (CSD2007- 00010) and European Union (SMALL PITN-GA-2009-23884)