1. Department of Medical Physics and Biophysics, University of South Bohemia, Jírovcova 24, České Budějovice 370 04, Czech Republic, Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague, Czech Republic, Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235-1604, and Aqueous Chemistry and Geochemistry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110