Ultrafast Molecular Spectroscopy in the Gas Phase

Abstract

This chapter gives an overview of ultrafast photoexcited molecular dynamics in the gas phase and their exploration via time-resolved spectroscopy. In the first part, we discuss the basics of ultrafast molecular motion in the framework of the Born–Oppenheimer approximation. We then discuss the coupled electronic–nuclear motion in situations where the Born–Oppenheimer approximation cannot be applied. The second part introduces the principles of valence- and core-level ionization before a systematic discussion of time-resolved gas-phase spectroscopy. Here, we demonstrate ultrafast valence- and core-level spectroscopic methods and show the latter’s strong sensitivity to electronic structure changes. The chapter ends with a short discussion of the synergetic information content of ultrafast spectroscopy compared to diffraction methods.