Anion ZEKE-spectroscopy of the weakly bound iodine water complex.

Zero kinetic electron energy photodetachment spectroscopy of I(-)·H(2)O and I(-)·D(2)O has been performed from 27 660 to 28 500 cm(-1) and from 27 660 to 35 900 cm(-1), respectively. The I(-)·D(2)O 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(-)·H(2)O, the I(-)·D(2)O 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.

Photodetachment-photoelectron spectroscopy of HS- x H2S and DS- x D2S: the transition states of the SH + H2S and SD + D2S reactions.

The transition state region for neutral hydrogen transfer reactions can be accessed by photodetachment of a stable negative ion with a geometry similar to that of the neutral transition state. In this work the SH + H(2)S and SD + D(2)S reactions are investigated by photodetachment-photoelectron spectroscopy of HS(-) x H(2)S and DS(-) x D(2)S. The spectra exhibit vibrational structure which is attributed to the antisymmetric stretching mode (H-atom motion) of the neutral transitions state for H-atom transfer. The spectra are compared to one-dimensional simulations performed using a wave packet propagation scheme. Electronic structure calculations of the anionic, neutral and transition-state geometries and calculations of the vertical detachment energy at different levels of theory are used to support the analysis of the spectra. A vertical detachment energy VDE of 3.06 eV has been determined.

Photodetachment-photoelectron spectroscopy of disulfanide: the ground and first excited electronic state of HS2 and DS2.

Photodetachment-photoelectron spectra of HS(2)(-) and DS(2)(-) are presented. The obtained electron affinities (EA (HS(2)) = 1.916 +/- 0.015 eV and EA (DS(2)) = 1.918 +/- 0.015 eV) are in good agreement with earlier results (S. Moran and G. B. Ellison, J. Phys. Chem., 1988, 92, 1794). Photodetachment into the neutral ground state of the radicals HS(2) and DS(2) leads to excitation of the S-S stretching mode, whereas photodetachment into the first excited state causes a S-S-H bending and a weak S-H stretching motion. Additionally, weak peaks of S(2) were observed in the spectra of HS(2) and DS(2), leading to the conclusion that photodetachment with 2.77 eV (448 nm) causes dissociation of HS(2)(-) and DS(2)(-) into S(2)(-) and H/D. Taking 2.77 eV as an upper limit for D(0)(S(2)(-)-H) a lower limit for Delta(f)H(0)(HS(2 (g))) of 100.8 kJ mol(-1) is obtained which is an improvement on the literature value of 107.145 +/- 10.46 kJ mol(-1).