Photodissociation spectroscopy of Ca+-H2O and Ca+-D2O

Electronic spectra are observed for the monosolvated metal cation complexes Ca+-H2O and Ca+-D2O using resonance enhanced photodissociation spectroscopy. The clusters are produced in a laser vaporization/supersonic expansion source and the mass-analyzed product is observed using a time-of-flight mass spectrometer. Both Ca+ and CaOH+ (or CaOD+) dissociation channels are observed on sharp resonances. Transitions from the ground electronic state to two excited electronic states are assigned, with vibrational progressions in the Ca-OH2 stretching mode. Spectroscopic constants are Ca+-H2O: (2) B-2(2)<--X (2)A(1) (T-0 = 21 464 cm(-1), Delta G(1/2)=357.9 cm(-1) and (2) B-2(1)<--X (2)A(1) (T-0=23 273 cm(-1), Delta G(1/2)=335.9 cm(-1)); and Ca+-D2O: (2) B-2(2)<--X (2)A(1) (T-0=21 447 cm(-1), Delta G(1/2)=350.9 cm(-1)) and (2) B-2(1)<--X (2)A(1) (T-0=23 261 cm(-1), Delta G(1/2)=324.1 cm(-1)). These transitions are rotationally resolved, confirming the structure of the complex to be C-2v. The Ca+-H2O bond distance is 2.22 Angstrom and the H-O-H bond angle is 106.8 degrees in the ground state. Comparisons with theoretical calculations are also made. (C) 1996 American Institute of Physics.