Transition state spectroscopy of the OH + H2 .fwdarw. H2O + H reaction via photodetachment of H3O- and D3O-

Theoretical calculation of photodetachment intensities for H3O−

“…Recently, de Beer et al 15 presented experimental photodetachment spectra of H 3 O Ϫ and D 3 O Ϫ as well as two degree of freedom simulation results. The experimental spectra were taken at two laser polarizations ϭ0°and ϭ90°.…”

“…The simulations of de Beer et al 15 explicitly treated the HO-H and H-H bonds. They performed ab initio calculations to obtain the anion potential as a function of these two coordinates.…”

“…For the anion surface we have used the surface of de Beer et al 15 15 The ground state wavefunction on this potential energy surface is localized in the H Ϫ •••H 2 O well, while excited states with у2 are delocalized across both wells. Very little information is available about the potential in the angular ͑bending͒ coordinates.…”

“…has become the benchmark of choice for quantum treatments of a four-atom reaction, 4-14 and de Beer et al 15 have recently carried out photodetachment experiments and simulations of H 3 O Ϫ and D 3 O Ϫ providing information on the potential energy surface of reaction ͑1.1͒. Despite the flurry of recent experimental and theoretical work on the OHϩH 2 reaction, the best available potential surface 16 still contains multiple flaws.…”

“…The anion has two stable geometries, H Ϫ •••H 2 O and HO Ϫ •••H 2 structures, neither of which lies close to the geometry of the neutral transition state. 15,17 The two anion species lead to distinctly different spectra at different laser polarizations, 15 and furthermore, excited vibrational states of the anion are delocalized over both geometries and can give FranckCondon overlap with the transition state. An additional difficulty is the lack of knowledge of both the anion and neutral surfaces.…”