Adaptive control of CO$_2$ bending vibration: deciphering field-system dynamics

TL;DR

This paper presents an adaptive control method combining phase-shaping and imaging to optimize CO$_2$ bending vibrations, revealing insights into field-induced structural changes during Coulomb explosion.

Contribution

It introduces a constrained phase-shaping approach for controlling molecular vibrations and demonstrates its effectiveness in enhancing CO$_2$ bending during strong-field excitation.

Findings

Achieved up to 56% enhancement of bending vibration.

Reduced parameter set improved transparency of dynamics.

Results align with theoretical models of field-induced structural changes.

Abstract

We combined adaptive closed-loop optimization, phase-shaping with a restricted search space and imaging to control dynamics and decipher the optimal pulse. The approach was applied to controlling the amplitude of CO$_2$ bending vibration during strong-field Coulomb explosion. The search space was constrained by expressing the spectral phase as a Taylor series, which generated pulses with characteristics commensurate with the natural physical features of this problem. Optimal pulses were obtained that enhanced bending by up to 56% relative to what is observed with comparably intense, transform limited pulses. We show that (1) this judicious choice of a reduced parameter set made unwrapping the dynamics more transparent and (2) the enhancement is consistent with field-induced structural changes to a bent excited state of CO$_2^{2+}$, which theoretical simulations have identified as the state from which the explosion originates.