Journal of Physical Chemistry A, Vol.103, No.32, 6339-6343, 1999
Is there any effect of solution microstructure on the solvated electron absorption spectrum in LiCl/H2O solutions?
Some years ago I. V. Kreitus measured changes in the optical characteristics of pulse radiolytically generated solvated electrons in solutions of LiCl in H2O and D2O over the LiCl concentration range 0-14.06 M (J. Phys. Chem. 1985, 89, 1987). With increasing LiCl concentration he observed a nonuniform blue-shift of the position of the e(solv)(-) absorption maximum and a similar discontinuous increase of the half-width of the absorption band. More rapid changes were observed just in those concentration regions which correspond to the stoichiometric mixtures such as LiCl . 6H(2)O and LiCl . 4H(2)O, respectively. Kreitus asserted that this effect is related to the microstructure of the solutions produced by Li+. He concluded finally that the high sensitivity of the e(solv)(-) absorption spectrum to slight microstructural changes in the medium could be used in future as a precise method for investigation of the solution structure. These experimental results and especially their interpretation have far reaching consequences. We therefore felt there is a need to repeat at least some of these measurements very carefully. It became all the more necessary as a femtosecond study on the solvation dynamics of electrons in concentrated aqueous LiCl solutions was interpreted according to the results of Kreitus. We report on our experimental results which neither corroborate the experimental data of Kreitus nor support his theoretical conclusions.