Interatomic Coulombic Decay in water clusters

Axe Théorie

Projet de recherche mené du 01/09/16 au 31/08/17.

Laboratoires co-porteurs
  • LCPMR
    Porteur de projet : Nicolas Sisourat
  • MONARIS
Mots clés

Intermolecular Coulombic Decay, water clusters, radiation damage

Le projet de recherche

Free electrons and radical cations produced by ionizing water molecules in biological organisms are responsible for most of the radiation damages. In particular, low energy electrons induce  significant damages in DNA via the so-called dissociative attachment mechanism. During the last decade a novel effect called Intermolecular Coulombic Decay (ICD) has been identified as a direct source of these genotoxic species (see figure): after ionization of a molecule in the inner-valence shell, this excited molecular ion transfers its excess energy to a neighboring molecule which is thus ionized. Two radical cations and a low energy electron are thus created. ICD has attracted a considerable and rising attention (see www.pci.uni-heidelberg.de/tc/usr/icd/ICD.refbase.html for a complete list of ICD publications).

The aim of the project was to investigate ab initio the ICD effect in small water clusters as biochemical model systems. ICD in these systems takes place after ionizing one water molecule in the 2a1 orbital. In brief for a water dimer,

H2O-H2O => H2O+*(2a1-1) - H2O + e-ph=> H2O+ + H2O+ + e-ph + e-ICD

The partners of this project are Dr. Nicolas Sisourat and Prof. Stéphane Carniato in LCPMR and Dr. Bruno Madebène in MONARIS. The project has started on the 1st of September 2016 with the recruitment for one year of Dr. Selma ENGIN as a postdoctoral researcher. 

We have first investigated ICD in water dimer using an original approach, so-called Fano-CI, for the computations of ICD lifetimes and a semiclassical method for modeling the nuclear dynamics. In collaboration with the group of Prof. Petr Slavicek in University of Chemistry and Technology in Prague, we have thus provided for the first time a complete ab initio  description of ICD in a hydrogen-bonded system. In particular, we have determined the efficiency of ICD in the water dimer. We have then investigated ICD in larger water clusters. During the project, the experimental group of Prof. Uwe Hergenhahn in Max Planck Institute for Plasma Physics in Garching measured the ICD efficiency in water clusters of different sizes. We have therefore started a collaboration with this group. A good agreement  between our two results was achieved. An article reporting the theoretical and experimental results is in preparation. 

As a "byproduct" of this study, we have shown that ICD can be used as a spectroscopic tool for probing the different weakly-bound and nearly isoenergetic conformers of molecular clusters. These results were published in The Journal of  Physical Chemistry A (J. Phys. Chem. A 121, 45 (2017)).

Results of this project were reported in the above cited paper, in 3 international conferences, 1 invited seminar and in 'Journée MiChem 2017'. As noted above, another article is in preparation. Furthermore, this project has initiated a fruitful collaboration of our group with two renown groups.

Publications
  • J. Phys. Chem. A 121, 45 (2017) + one in preparation
Interventions
  • Journée MiChem 2017 
  • International Workshop on "Dynamics of Energy Transfer on the Nanoscale" in Berlin, September 25 - 27, 2017 - DPG conference in Erlangen, March 4 - 9, 2018
  • International Workshop on "Intermolecular Coulombic Decay and related processes" in Paris, April 17 - 18, 2018
  • Invited seminar in Institute of Applied Physics and Mathematics in Beijing, May 2, 2018