The work contained in this volume is representative of the presentations made by the participants at the Fifth International Conference on Time-Resolved Vibra­ tional Spectroscopy, which was held at Waseda University, Tokyo, Japan, from June 3 to 7, 1991. The conference was the fifth in a biennial series initiated in 1982 by Prof. George H. Atkinson (University of Arizona) at Lake Placid, USA, and subsequently convened by Prof. Alfred Laubereau (University of Bayreuth, Germany) and Dr. Manfred Stockburger (Max-Planck Institut, G6ttingen, Ger­ many) at Bayreuth-BischofsgrUn, Germany, in 1985, by Prof. Joop D.W. Van Voorst (University of Amsterdam) at Amersfoort, The Netherlands, in 1987, and by Prof. Thomas G. Spiro (princeton University) at Princeton, USA, in 1989. The purpose of the conference is to bring together researchers from various disciplines and provide a forum for discussion of the latest advances in time­ resolved spectroscopies concerned with transient vibrational phenomena and their application to fundamental scientific and engineering studies. The 167 registered participants, including 46 students, from 14 different countries, represented a wide range of scientific disciplines, and clearly indicated that the field continues to expand into new areas of physics, chemistry, biology, and materials science. Their enthusiasm and the originality and quality of the contributions presented produced a very successful and enjoyable conference.