Computer investigations on the mechanism of the influence of quencher concentration on the rate of simple bimolecular reaction.
Molecular dynamics investigations on the influence of the concentration of B (quencher) on the rate coefficient, k(t), for the reaction A+B-->C+B are continued [M. Litniewski, J. Chem. Phys. 123, 124506 (2005); 124, 114501 (2006)]. The problem is investigated by analyzing the excess in the two-particle probability density function and in its radial moments. The simulations have been performed for the deterministic systems as gas and liquid as well as for the Brownian system. The influence of moderate changes of the reaction radius resulting in changes of the activation energy has been also considered. The most important result is that the excess in k(t) may be not only a direct consequence of fluctuations in concentrations. For the gas, the excess in the mean radial velocity of A towards B dominated over the excess in the value of the probability density function. As a result, the excess in k(t) was negative in spite of the excess in the relative spatial correlations between A and B was positive. The excess in the mean radial velocity was completely unimportant for dense liquids and the Brownian system.
Litniewski
Marek
M
Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland. mark@ichf.edu.pl