Investigation of charging dynamics in atomic clusters on an attosecond timescale

• Applicant: Dr. Bernd Schütte
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263667282

Atomic clusters are fascinating objects of research and can be regarded as a model for complex systems such as biomolecules. The interaction of an intense light pulse with a cluster leads to high electric charging of the cluster and its expansion, followed by a complete disintegration. The understanding of processes taking place during the interaction of a low-frequency light pulse with a cluster is far from complete. It is expected that multiphoton ionization and electron impact ionization driven by the laser field are the most dominant processes. This project aims to substantially improve the picture of cluster charging. In a first step, cluster ionization will be studied with photoelectron spectroscopy techniques using few-cycle near-infrared and mid-infrared pulses. In this way, and by varying the pulse length, valuable information will be obtained about the interplay between multiphoton ionization and laser-driven electron impact ionization. The significance of the two processes is expected to depend both on the pulse length and the ionization wavelength. In a second step, it is aimed to study cluster ionization in real time. Driven by the development of high-order harmonic sources, it is now possible to generate light pulses with attosecond (1 attosecond =10-18s) pulse duration, which is the natural time scale of electrons. These pulses will be used as a probe for the investigation of charging processes in atomic clusters during ionization with intense near-infrared pulses. Photoelectrons generated by the attosecond pulse experience an energy downshift that depends on the current cluster charge. The energy downshift will be measured at different delays between the near-infrared and the attosecond pulse, allowing the time-resolved observation of the cluster charge. This so far unaccessible information will be a huge step in the understanding of electron dynamics in clusters and extended systems in general.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Jon Marangos