This book summarizes several years of research carried out by a collaboration of many groups on ultrafast photochemical reactions. It emphasizes the analysis and characterization of the nuclear dynamics within molecular systems in various environments induced by optical excitations and the study of the resulting molecular dynamics by further interaction with an optical field.

The present monograph summarizes, in a comprehensive way, several years of joint experimental and theoretical frontier research on ultrafast laser-induced molecular dynamics and its control. Emphasis is set on the characterization of the nuclear dynamics within molecular systems in various environments (gas phase, surfaces, solids, solution, strong fields) triggered by optical excitations spanning from the infrared to the ultraviolet. Building on the converged analysis between experiment and theory, control of chemical reactions is established by means of optimally shaped laser pulses. This paves the road toward new applications and future challenges in this rapidly developing research field.

Following Herzberg's classic books on Molecular Spectra, this is the first book completely devoted to triatomic molecules and clusters. The book covers a self-consistent introduction, and parts on theoretical and experimental tools. All relevant systems from H3 to noble gas trimers are treated.