1. Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy