Laser Induced Chemical Processes

The possibility of initiating chemical reactions by high-intensity laser exci tation has captured the imagination of chemists and physicists as well as of industrial scientists and the scientifically informed public in general ever since the laser first became available. Initially, great hopes were held that laser-induced chemistry would revolutionize synthetic chemistry, making possible "bond-specific" or "mode-specific" reactions that were impos sible to achieve under thermal equilibrium conditions. Indeed, some of the early work in this area, typically employing high-power continuous-wave sources, was interpreted in just this way. With further investigation, however, a more conservative picture has emerged, with the laser taking its place as one of a number of available methods for initiation of high-energy chemical transformations. Unlike a number of these methods, such as flash photolysis, shock tubes, and electron-beam radiolysis, the laser is capable of a high degree of spatial and molecular localization of deposited energy, which in turn is reflected in such applications as isotope enrichment or localized surface treatments. The use of lasers to initiate chemical processes has led to the discovery of several distinctly new molecular phenomena, foremost among which is that of multiple-photon excitation and dissociation of polyatomic molecules. This research area has received the greatest attention thus far and forms the focus of the present volume.

Laser Processing and Chemistry gives an overview of the fundamentals and applications of laser-matter interactions, in particular with regard to laser material processing. Special attention is given to laser-induced physical and chemical processes at gas-solid, liquid-solid, and solid-solid interfaces. Starting with the background physics, the book proceeds to examine applications of laser techniques in micro-machining, and the patterning, coating, and modification of material surfaces. This third edition has been revised and enlarged to cover new topics such as the synthesis of nanoclusters and nanocrystalline films, ultrashort-pulse laser processing, laser polishing, cleaning, and lithography. Graduate students, physicists, chemists, engineers, and manufacturers alike will find this book an invaluable reference work on laser processing.

Laser Processing and Chemistry gives an overview of the fundamentals and applications of laser-matter interactions, in particular with regard to laser material processing. Special attention is given to laser-induced physical and chemical processes at gas-solid, liquid-solid, and solid-solid interfaces. Starting with the background physics, the book proceeds to examine applications of laser techniques in micro-machining, and the patterning, coating, and modification of material surfaces. This third edition has been revised and enlarged to cover new topics such as the synthesis of nanoclusters and nanocrystalline films, ultrashort-pulse laser processing, laser polishing, cleaning, and lithography. Graduate students, physicists, chemists, engineers, and manufacturers alike will find this book an invaluable reference work on laser processing.

This conference on both the physics and chemistry of laser-induced processes in molecules was organized by the Quantum Electronics Divisional Board of the European Physical Society whose membership is given on p.367. The confer ence aim, to mix physicists and chemists interested in this exciting field both from Europe and further afield, was well fulfilled by the attendance of around 250 participants and the submission of about 100 papers, which dre presented here. Numerous people at both the Physics Department, Heriot-Watt University, Edinburgh, and at the Projektgruppe fUr Laserforschung, MPI, Garching, con tributed hard work to the organization; in addition to Dr. Bob Harrison, who bore the biggest burden with conspicuous success, we particularly thank Hugh MacKenzie, Richard Dennis and last but not least Miss Joanne Askham and the secretaries in Edinburgh together with Frau Doris Maischberger and the secretaries in Garching. December 1978 K.L. Kompa S.D. Smith Conren~ Part I. Study of Lasers and Related Techniques Suitable for Applications in Chemistry and Spectroscopy Rare Gas Halogen Lasers and Photochemical Applications. By S.D. Rockwood ... 3 Group VI Molecular Photolytic Dissociation Studies Using Rare Gas Halide Lasers. By M.C. Gower, A.J. Kearsley, and C.E. Webb ... 8 Broadly Tunable UV Source Based on Stimulated Raman Scattering.

Materials processing with lasers is a rapidly expanding field which is increasingly captivating the attention of scientists, engineers and manufacturers alike. The aspect of most interest to scientists is provided by the basic interaction mechanisms between the intense light of a laser and materials exposed to a chemically reactive or nonreactive surrounding medium. Engineers and manufacturers see in the laser a new tool which will not only make manufacturing cheaper, faster, cleaner and more accurate but which also opens up entirely new technologies and manufacturing methods that are simply not available using existing techniques. Actual and potential applications range from laser machining to laser-induced materials transformation, coating, patterning, etc. , opening up the prospect of exciting new processing methods for micromechanics, metallurgy, integrated optics, semiconductor manufacture and chemical engineering. This book concentrates on the new and interdisciplinary field of 1 aser-i nduced chemicaZ process i ng of materi als. The techni que permits maskless single-step deposition of thin films of metals, semiconductors or insulators with lateral dimensions ranging from a few tenths of a micrometer up to several centimeters. Moreover, materials removal or synthesis, or surface modifications, such as oxidation, nitridation, reduction, metallization and doping, are also possible within similar dimensions. This book is meant as an introduction. It attempts to cater for the very broad range of specific interests which different groups of readers will have, and this thinking underlies the way in which the material has been arranged.