1. a Hahn-Meitner Institut Berlin Gmb H, Bereich Strahlenchemie , Glienicker Strasse 100, D-1000 , Berlin 39 , FRG
2. b Department of Chemistry , The University of Arizona , Tucson , Arizona , 85721 , USA
3. c Department of Chemistry , University of Kansas , Lawrence , Kansas , 66045-0046 , USA