Advanced mass spectrometry experiments are nowadays a fundamental tool for investigating structure and reactivity of different size molecular systems.

by Dr Riccardo Spezia (Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, UMR 8587 CNRS, Université d'Evry Val d'Essonne)

Monday May 19, 2008, 3:00 PM → 5:00 PM Europe/Rome

Sala Touschek (Dip Fisica - Ed. G.Marconi)

Molecular ions are produced in gas phase from a liquid phase in a soft way, by using Electrospray (ESI) and then they can be selected by their mass/charge ratio. Thus a unique species can be injected in the collision room where by the impact with an inert gas the ion can dissociate. Fragmentation products are analysed in term of their mass/charge ratio and the relative intensity of the different products can be followed as a function of collision energy. By linking these experimental observations with theoretical tools it is possible to make hypothesis on the initial structure and on the reaction mechanisms. Direct dynamics simulations are devoted to answer to the following questions: 1) what is the structure that is at the origin of the observed products? 2) What is the fragmentation mechanism? We show how a QM/MM molecular dynamics approach can be adapted at this aim, by applying that to a simple prototypical case of Urea collision induced dissociation.