Ultrafast and ultra-intense AMO physics and physical chemistry is explored by new x-ray sources such as high harmonic generation. Isolated attosecond pulses in the extreme ultraviolet are used to probe strong field ionization and to initiate electronic and vibrational superpositions in atoms and small molecules. The results provide exceptional spectral and time resolution to probe chemical dynamical processes in atoms and molecules. Step-like features in the risetimes of strong field ionization of atoms are due to the subcycles of the 800 nm ionizing pulse. These are observed and compared with theory to elucidate instantaneous versus effective hole dynamics. Isolated attosecond pulses create extensive superpositions of electronic and vibrational states, which are revealed by time-delayed 800 nm manipulation pulses. The results provide specifically subcycle interferences, level shifting, and quantum beats imprinted onto the attosecond pulse as a function of time delay. Detailed outcomes are compared to theory for measurements of time-dynamic processes by attosecond transient absorption.

Attosecond dynamics: A time resolved x-ray spectroscopic revolution

252nd National Meeting (2016)

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