Imaging H2O Photofragments in the Predissociation of the HCl-H2O Hydrogen-Bonded Dimer

The state-to-state vibrational predissociation (VP) dynamics of the hydrogen-bonded HCl-H2O dimer was studied following excitation of the dimer's HCl stretch by detecting the H2O fragment Velocity map imaging (VMI) and resonance-enhanced multiphoton ionization (REMPI) were used to determine pair-correlated product energy distributions. Following vibrational excitation of the HCl stretch of the dimer, H2O fragments were detected by 2 + 1 REMPI via the (C) over tilde B-1(1) (000) <- (X) over tilde (1)A(1) (000) transition. REMPI spectra dearly show H2O from dissociation produced in the ground vibrational state. The fragments' center-of-mass (c.m.) translational energy distributions were determined from images of selected rotational states of H2O and were converted to rotational state distributions of the HCl cofragment. The distributions were consistent with the previously measured dissociation energy of D-0 = 1334 +/- 10 cm(-1) and show a dear preference for rotational levels in the HCl fragment that minimize translational energy release. The usefulness of 2 + 1 REMPI detection of water fragments is discussed.