1. Department of Physical Chemistry, Institute of Chemical Technology, Technická 5, Prague 6, Czech Republic and J. Heyrovský Institute of Physical Chemitsry, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic; Helmholtz-Zentrum Berlin für Materialien and Energie, and BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin, and Max-Born-Institut für Nichtlineare Optik and Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany Max-Planck-Institut für Dynamik and...