Eur. Phys. J. D 60, 77-83 (2010)
https://doi.org/10.1140/epjd/e2010-00013-0

Theoretical investigation of the ultrafast dissociation of core-ionized water and uracil molecules immersed in liquid water

¹ Instituto de Física Rosario (CONICET-Universidad Nacional de Rosario), Avenida Pellegrini 250, 2000 Rosario, Argentina
² Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, LAMBE, UMR-CNRS 8587, Université d'Evry-Val-d'Essonne, bd. F. Mitterrand, Bât. Maupertuis, 91025 Evry, France
³ Institut Universitaire de France, 103 bd. Saint-Michel, 75005 Paris, France
⁴ Département de chimie, École Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
⁵ Institut de Minéralogie et de Physique des Milieux Condensés, IMPMC, UMR-CNRS 7590, Université Pierre et Marie Curie, Campus Boucicaut, 140 rue de Lourmel, 75015 Paris, France

Corresponding author: ^a penhoat@impmc.upmc.fr

Received: 9 November 2009
Revised: 22 December 2009
Published online: 26 January 2010

Abstract

We present a series of ab initio density functional based calculations of the fragmentation dynamics of core-ionized biomolecules. The computations are performed for pure liquid water, aqueous and isolated Uracil. Core ionization is described by replacing the 1s² pseudopotential of one atom of the target molecule (C, N or O) with a pseudopotential for a 1s¹ core-hole state. Our results predict that the dissociation of core-ionized water molecules may be reached during the lifetime of inner-shell vacancy (less than 10 fs), leading to OH bond breakage as a primary outcome. We also observe a second fragmentation channel in which total Coulomb explosion of the ionized water molecule occurs. Fragmentation pathways are found similar for pure water or when the water molecule is in the primary hydration shell of the uracil molecule. In the latter case, the proton may be transferred towards the uracil oxygen atoms. When the core hole is located on the uracil molecule, ultrafast dissociation is only observed in the aqueous environment and for nitrogen-K vacancies, resulting in proton transfers towards the hydrogen-bonded water molecule.