Adaptive control of theCO2bending vibration: Deciphering field-system dynamics

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 the $\mathrm{C}{\mathrm{O}}_{2}$ 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 $\mathrm{C}\mathrm{O}_{2}{}^{2+}$, which theoretical simulations have identified as the state from which the explosion originates.