Gas-phase photoacoustics are treated comprehensively for the first time in this book. Review articles by leading scientists in the respective research areas introduce their fields, review present knowledge and conclude with the latest developments and future prospects. Topics covered include the theory of photoacoustics in the frequency and time domains, acoustic resonator models, a great variety of experimental setups and techniques, studies of spectrocopy and fundamental kinetic processes such as energy transfer and chemical reactions, and applications such as air and exhaust monitoring and trace gas detection in biology and agriculture. The book will interest newcomers to photoacoustics, since it gives an overview of the important directions of current research and detailed descriptions of experimental methods. It will also be a valuable source of information for those already involved in photoacoustic research due to its clear presentation of theory and experimental results. All relevant literature references in this rapidly expanding field of laser applications are included.