Attosecond pulses and laser-driven electron dynamics

The discovery of high-order harmonic generation in the late 1980s and the subsequent realization of attosecond temporal confinement of the emitted radiation, have stimulated significant interest in the study of attosecond phenomena in atoms, molecules, and solids. In the last two decades, technological advances in laser technology have permitted the development of isolated attosecond pulse sources spanning the extreme ultraviolet and extending into the soft X-ray region of the spectrum, and have stimulated the development of time-resolved spectroscopies and sophisticated theory techniques capable of following the electron dynamics of quantum systems in the time domain. In particular, attosecond science has allowed unique insight into laser-driven dynamics occurring on sub-optical cycle time scales, including ionization, high-order harmonic generation, Stark shifts, and other processes. The techniques are now sufficiently sophisticated to follow non-adiabatic electronic processes in gas-phase molecules, and to probe the dynamics of quantum phase transitions in solids. In this chapter, we review the techniques and technologies for generating attosecond pulses through high-order harmonic generation, and highlight some recent advances in the applications of attosecond pulses to study dynamics in atoms, molecules, and solids.