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Journal of Physical Chemistry C 114 (2010) 12667-12674
Radiolysis of Water Confined in Porous Silica: A Simulation Study of the Physicochemical Yields
H. Ouerdane1, B. Gervais1, H. Zhou2, 3, M. Beuve2, 3, J.-P. Renault4

We investigate the radiolysis of liquid water confined in a porous silica matrix by means of an event-by-event Monte Carlo simulation of electron penetration in this composite system. We focus on the physical and physicochemical effects that take place in the picosecond range, before the radicals start to diffuse and react. We determine the radiolytic yields of the primary species for a system made of cylindrical pores filled with water over a wide range of pore radii RC. We show that the relative position of the conduction band edge V0 in both materials plays a major role in the radiolysis of composite systems. Due to its lower V0 as compared to that of silica, water acts as a collector of low-energy electrons, which leads to a huge enhancement of the solvated electron yields for RC ≤ 100 nm. The confinement has also a marked effect on the spatial distribution of the radicals, which become isolated in a very large number of pores as RC decreases.
1 :  CIMAP - UMR 6252 - Centre de recherche sur les Ions, les MAtériaux et la Photonique
2 :  IPNL - Institut de Physique Nucléaire de Lyon
3 :  LIRIS - Laboratoire d'InfoRmatique en Image et Systèmes d'information
4 :  IRAMIS - Institut Rayonnement Matière de Saclay (ex DRECAM)