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

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.

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