Water Molecules in Ultrashort Intense Laser Fields

TL;DR

This study explores how water molecules ionize under ultrashort intense laser pulses, revealing orbital-specific ionization behaviors and phase effects that impact molecular imaging techniques.

Contribution

It provides a theoretical analysis of water ionization dynamics in intense laser fields, highlighting the orbital contributions and phase dependence relevant for imaging applications.

Findings

1b1 orbital dominates overall ionization

Lower-lying 3a1 orbital influences ionization in the nodal plane

Ionization yield ratios depend on laser intensity and phase

Abstract

Ionization and excitation of water molecules in intense laser pulses is studied theoretically by solving the three-dimensional time-dependent electronic Schr\"odinger equation within the single-active-electron approximation. The possibility to image orbital densities by measurement of the orientation-dependent ionization of H2O in few-cycle, 800nm linear-polarized laser pulses is investigated. While the highest-occupied molecular orbital 1b1 is found to dominate the overall ionization behavior, contributions from the energetically lower lying 3a1 orbital dominate the ionization yield in the nodal plane of the 1b1 orbital. The ratio of the ionization yields of the two orbitals depends on the intensity. Furthermore, even for laser pulses as long as 8 cycles the orientation-dependent ion yield depends on the carrier-envelope phase. In the interpretation of the orientation-dependent ionization as an imaging tool these effects have to be considered.