Tracking ultrafast non-adiabatic dissociation dynamics of the deuterated water dication molecule.

We applied reaction microscopy to elucidate fast non-adiabatic dissociation dynamics of deuterated water molecules after direct photo-double ionization at 61 eV with synchrotron radiation. For the very rare D+ + O+ + D breakup channel, the particle momenta, angular, and energy distributions of electrons and ions, measured in coincidence, reveal distinct electronic dication states and their dissociation pathways via spin-orbit coupling and charge transfer at crossings and seams on the potential energy surfaces. Notably, we could distinguish between direct and fast sequential dissociation scenarios.

Direct Measurement of Charge Transfer Probability during Photodissociation of Few-keV OD Beam.

We have measured the photodissociation of few-keV OD molecular ions into either D + O or O + D final products. The three-dimensional momentum imaging measurements of the light and massive fragments in coincidence were enabled by using an upgraded two-detector setup. In this work, we show that absorption of a single 790 or 395 nm photon excites the OD from its electronic ground state to the B state, which dissociates to the O(S) + D dissociation limit.

Mutual neutralization in collisions of Li with CN.

The mutual neutralization reaction in collisions of Li with CN is a promising candidate for rigorous multi-dimensional studies of atom-molecule charge transfer processes. The reaction is driven by the non-adiabatic interaction between the lowest two A' electronic states at large Li-CN distances, resulting in a large cross section for mutual neutralization. As a first step, the relevant adiabatic potential energy surfaces and non-adiabatic interaction are computed , and the process is studied quantum mechanically using the vibrational sudden approximation, where the vibrational and rotational motions of the CN molecule are assumed to be frozen during the collision.

Efficiency of charge transfer in changing the dissociation dynamics of OD+ transients formed after the photo-fragmentation of D2O.

We present an investigation of the relaxation dynamics of deuterated water molecules after direct photo-double ionization at 61 eV. We focus on the very rare D+ + O+ + D reaction channel in which the sequential fragmentation mechanisms were found to dominate the dynamics. Aided by theory, the state-selective formation and breakup of the transient OD+(a1Δ, b1Σ+) is traced, and the most likely dissociation path-OD+: a1Δ or b1Σ+ → A 3Π → X 3Σ- → B 3Σ--involving a combination of spin-orbit and non-adiabatic charge transfer transitions is determined.

Atomic autoionization in the photo-dissociation of super-excited deuterated water molecules fragmenting into D + O + D.

We present the relaxation dynamics of deuterated water molecules autoionization, initiated by the absorption of a 61 eV photon, producing the very rare D + O + D breakup channel. We employ the COLd target recoil ion momentum spectroscopy method to measure the 3D momenta of the ionic fragments and emitted electrons from the dissociating molecule in coincidence. We interpret the results using the potential energy surfaces extracted from multi-reference configuration interaction calculations.