Bond-selective fragmentation of water molecules with intense, ultrafast, carrier envelope phase stabilized laser pulses

TL;DR

This study demonstrates that carrier envelope phase stabilized ultrafast laser pulses can control the bond-breaking pathways and energy release in water molecule dications, revealing isotope-dependent dissociation dynamics.

Contribution

It introduces the use of CEP-stabilized 5 fs laser pulses to control and study water molecule dissociation with observable isotope-dependent effects.

Findings

CEP influences dissociation channel ratios in HOD$^{2+}$

The OD$^+$/OH$^+$ ratio varies from 150% to over 300% with CEP

Kinetic energy release depends on CEP

Abstract

Carrier envelope phase (CEP) stabilized pulses of intense 800 nm light of 5 fs duration are used to probe the dissociation dynamics of dications of isotopically-substituted water, HOD. HOD$^{2+}$ dissociates into either H$^+$ + OD$^+$ or D$^+$ + OH$^+$. The branching ratio for these two channels is CEP-dependent; the OD$^+$/OH$^+$ ratio (relative to that measured with CEP-unstabilized pulses) varies from 150% to over 300% at different CEP values, opening prospects of isotope-dependent control over molecular bond breakage. The kinetic energy released as HOD$^{2+}$ Coulomb explodes is also CEP-dependent. Formidable theoretical challenges are identified for proper insights into the overall dynamics which involve non-adiabatic field ionization from HOD to HOD$^+$ and, thence, to HOD$^{2+}$ via electron rescattering.