Anion ZEKE-Spectroscopy of the Weakly Bound Iodine Water Complex

Zero kinetic electron energy photodetachment spectroscopy of I−·H2O and I−·D2O has been performed from 27 660 to 28 500 cm−1 and from 27 660 to 35 900 cm−1, respectively. The I−·D2O spectral data and theoretical studies resulted in a reassignment of earlier anion-ZEKE spectra of iodide water ( Bässmann C. ; et al. Int. J. Mass Spectrom. Ion Processes 1996, 159, 153 ). In opposite to the I−·H2O, the I−·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 (v = 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.