Anion ZEKE-Spectroscopy of the Weakly Bound Iodine Water Complex

Zero kinetic electron energy photodetachment spectroscopy of I-center dot H2O and I-center dot D2O has been performed from 27 660 to 28 500 cm(-1) and from 27 660 to 35 900 cm(-1), respectively. The I-center dot D2O spectral data and theoretical studies resulted in a reassignment of earlier anion-ZEKE spectra of iodide water (Bassmann, C.; et al. Int. J. Mass Spectrom. Ion Processes 1996, 159, 153). In opposite to the I-center dot H2O, the I-center dot D2O spectrum reveals a regular progression of the iodine-water van der Waals stretching mode and a short progression of even quanta of the van der Waals rocking mode. A rough estimation delivers dissociation thresholds of the anionic and of the lower and the upper spin-orbit component of the neutral van der Waals complex. A high resolution ZEKE spectrum of the van der Waals stretching mode (nu = 1) reveals significant fine structure, which is found again in a former photodissociation spectrum of the anionic complex (Ayotte, P.; et al. J. Phys. Chem. A 1998, 102, 3067). Our assignments are supported by theoretical calculations of molecular structures and vibrational motions. Vibrational frequencies and isotope effects are reproduced very satisfyingly by these calculations.