Attosecond metrology and application of high harmonics

Abstract

Real-time studies of ultra-fast evolving quantum systems require even faster probe mechanisms. For electronic systems on the atomic scale subfemtosecond laser pulses are suitable. High-order harmonic generation can produce the necessary broad spectrum to support such short pulses. Under certain phase-matching conditions a subset of the emitted radiation can be well phase-locked resulting in attosecond laser pulses. To extract sound information from the experiments' results, accurate and reliable temporal and structural assessment of these pulses is indispensable. Various attosecond metrology methods have been proposed and some applied. Most of these rely either on a two-color photo-ionization of an atomic system by both the extreme-ultraviolet attosecond pulses and the fundamental infrared radiation together or they rely on a second-order autocorrelation based on a two-photon ionization by the mere attosecond pulses alone. Two techniques underlying most of the attosecond metrology methods were compared and evaluated. These are the reconstruction of attosecond beating by interference of two-photon transitions (RABITT) and the second- order intensity volume-autocorrelation (2IVAC). Despite considerable controversy on the applicability and reliability of these two methods, a direct comparison between them has been missing. This thesis