Tunneling through light-induced molecular potentials in Ar-2(+) - art. no.023401

A photodissociation study is reported on the simply structured molecular io n Ar-2(+) that is, to good approximation a two-electronic state system (one bound, the other dissociative) under the conditions of this experiment. No nlinear behavior is manifest in characteristically changed dissociation dyn amics as a function of laser intensity in strong laser fields (less than or equal to 5 x 10(12) W/cm(2)). Light-induced molecular potentials (molecula r dressed states) provide a convenient description under such conditions an d predict surprising effects regarding molecular dynamics in a light field. Much care has been taken to assure a meaningful quantitative comparison of experimental results with numerical simulations. This leads to the identif ication of dissociation by tunneling through a light-induced molecular pote ntial well. Ar-2(+) is generated in a de-discharge, accelerated, and formed into a mass selected molecular beam (7.5 keV). For some experiments, molec ules are prepared in low vibrational states only, before they interact with a high intensity laser beam at a wavelength of 532 nm. The momentum distri bution of photofragments is measured using an imaging technique for neutral fragments.