Photo-Excited Processes, Diagnostics and Applications covers the area of photo-excitation and processing of materials by photons from the basic principles and theories to applications, from IR to x-rays, from gas phase to liquid and solid phases. The various chapters give a wide spectral view of this developing field. The research of photo-excited processes usually involves, in one form or another, the multitude of interactions between photons, electrons and atoms. One finds, for example, scientists who confine themselves to studying only the interactions between photons and electrons in order to create useful physical optical effects such as dynamic holograms. There are also those who look for direct ways of using photon-excited electrons to deposit or ablate atoms on surfaces for various electronic and electro-optic purposes. Thus, photo-excited-processes encompass a wide spectrum of sciences and disciplines ranging from physics and optoelectronics to materials science and photochemistry. It is for this reason that the goal set for this book was to choose a number of concepts and techniques, from fundamentals to advanced applications, and present all of them together to provide a "snap-shot" of the PEPDA fields. The reader can find herein a blend of topics such as physics of quantum excitations, optical advances and photochemical processing of materials in various phases. New concepts for diagnostics, processing of materials and micro-structuring of devices, using beams of photons are also included. Twelve leading groups worldwide set down to write this book during the past two years which include the most updated techniques used in their laboratories for investigating photo-excited processes and new applications. This book will be useful to scientists and engineers who have a strong interest in photo-assisted processes development for microelectronics and photonics.