Attosecond X-Ray Pulses for Molecular Electronic Dynamics

Attosecond pulses are opening a wide new field on the border of chemistry and physics. They offer the opportunity to initiate and probe electronic rearrangement of atoms, molecules, solids and clusters on the natural timescale of the electron motion. This thesis is about making and measuring attosecond pulses, with the ultimate goal of applying attosecond spectroscopy to molecules. In chapter 1, attosecond spectroscopy is reviewed in general. The applications of attosecond pulses to atoms and molecules, including successful experiments and theoretical predictions, are discussed. In chapter 2, techniques for making and measuring attosecond radiation are presented. This chapter focuses on high harmonic generation from tabletop laser sources, since synchrotron- and free-electron laser-based techniques are not yet experimentally demonstrated. Chapters 3 and 4 discuss in detail the laboratory setup for attosecond pulse generation, including the laser source, optical diagnostics, and attosecond delay line. The attosecond control of free electron motion with few-cycle laser pulses is presented in chapter 5. There, the carrier-envelope phase (CEP), and thus the attosecond temporal evolution of the laser field, leads to quantum interferences between free electron wavefunctions and lends control over the direction of electron emission. Attosecond pulse production is achieved in chapter 6 by gating harmonic generation on the leading edge of the driving laser pulse. The gate mechanism is shown to rely on the macroscopic ionization of the harmonic generation medium. This final chapter also demonstrates a new technique for assessing attosecond pulse temporal structure based on the inversion of the driving laser field in the laboratory frame of reference, called CEP-scanning