Determination of ionization dynamical parameters by time-resolved photoelectron imaging

Abstract

A theoretical formalism is developed for photoelectron angular distributions from an aligned ensemble of molecules observed by a time-resolved photoelectron imaging experiment (TRPEI) in the gas phase. Rotational motion is treated quantum mechanically, and photo-ionization in the perturbative regime is considered. We introduce state multipoles of the ionization laser field and express the photoelectron anisotropy parameters by a double expansion with molecular axis alignment parameters and state multipoles of the field. In order to analyse the feasibility of the full determination of the dynamical parameters and examine multiple solutions for the quadratic equations of the dynamical parameters, we introduce G and H matrices by decoupling the geometrical factors and the already known dynamical factors from the unknown dynamical factors. The usefulness of multichannel quantum defect theory in the analysis of TRPEI is described.

Keywords:

• Photoelectron angular distribution
• Ionization dynamical parameters
• Multichannel quantum defect theory
• Molecular alignment
• Photoelectron imaging

Acknowledgements

This work was supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (17205004 and 15002011). Y.S. acknowledges the special postdoctoral research program of RIKEN.