Laser-driven nonlinear cluster dynamics
Résumé
Laser excitation of nanometer-sized atomic and molecular clusters offers insight into complex many-particle dynamics from several perspectives. Whereas weak laser fields allow the analysis of photoionization, excited-state relaxation, and structural modifications on these finite quantum systems, violent collective electron motion and Coulomb explosion can be explored with intense laser pulses. This review provides an overview of key phenomena arising from laser-cluster interactions with focus on nonlinear optical excitations and discusses underlying processes according to the current understanding. A brief general survey covers basic cluster properties and excitation mechanisms relevant for laser-driven cluster dynamics. Then, after an excursion in theoretical and experimental methods, results for single- and multiphoton excitations are reviewed with emphasis on signatures from time- and angular-resolved photoemission. The broad spectrum of phenomena arising from clusters in strong fields is closely related to the creation of dense nanoplasmas, the dynamics of which is a major issue of this review. The implications for technical developments include the controlled generation of ion, electron, and radiation pulses as will be addressed along with corresponding examples. Finally, future prospects of laser-cluster research and experimental as well as theoretical challenges are discussed.