52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021;
Virtual; Time Zone: Central Daylight Time, USA
Session X02: Focus Session: Probing and Controlling Matter with Intense Light
8:00 AM–10:00 AM,
Friday, June 4, 2021
Chair: Loren Greenman, Kansas State University
Abstract: X02.00004 : Exploiting Coherences to Probe Strong-Field Molecular Ionization Dynamics*
8:54 AM–9:24 AM
Live
Abstract
Presenter:
Robert R Jones
(Univ of Virginia)
Author:
Robert R Jones
(Univ of Virginia)
Ionization is a common central feature of strong-field molecular physics. It serves as the critical first step in high-harmonic and attosecond pulse generation, and can establish electronic coherences and charge migration dynamics in the molecular ion. Not surprisingly, the orientation of a molecule relative to the polarization of an intense ionizing laser can play an essential role in inducing, controlling, and probing the intramolecular dynamics resulting from strong-field ionization. Hence, it is important to understand that orientation dependence. One approach for measuring angle-dependent (non-dissociative) ionization yields is to preferentially orient the target molecules in the laboratory frame, prior to their exposure to the intense ionizing field. Depending on the orientation technique, the effectiveness of this approach can be limited by the degree of achievable orientation, the presence of strong orienting fields during the ionization pulse, and/or background ionization induced by the orienting field. We have recently explored a different method, using an asymmetric 2-color ionizing field and the anisotropic ionization process itself to coherently alter the rotational distributions in both the molecular ions and surviving neutrals. The angular distribution of ion fragments produced via Coulomb explosion in a more intense time-delayed probe, is then used to track the coherent motion of the rotational wavepackets. For linear and symmetric top molecules, which exhibit pronounced rotational revival structures during their evolution, one can distinguish the rotational motion of neutral and ion species by their different revival times. By fitting the observed rotational revivals to a model that includes both strong-field ionization anisotropy and non-ionizing Raman and hyper-Raman rotational redistribution, the angle-dependent ionization rate can be extracted. The method can, in principal, be extended to determine the angle-dependent ionization rate into different electronic, and perhaps even vibrational, states of the ion.
*This work has been supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Award DE-SC0012462.