1. Dipartimento di Chimica IFM, Università di Torino, Via Pietro Giuria 7, 10125 Turin, Italy, Fire Science Division, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Physics, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201, and Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201