I. KLEINER, Laboratoire de Photophysique Moléculaire, Université Paris Sud, 91405 Orsay, France; N. MOAZZEN-AHMADI, Department of Physics, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada; A. R. W. MCKELLAR, Stracie Institute for Molecular Science, National Research Council, Ottawa, Canada, K1AOR6; J. T. HOUGEN, Optical Physics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.