Photoinduced charge-transfer reaction at surfaces. Part I. (HCl)m..Nan/LiF(001) + hv (640 nm)-->(HCl)m - 1...

A sub-monolayer of atomic sodium, Nan, was deposited on LiF(001) at 50 K and characterized by temperature-programmed desorption, X-ray photoelectron spectroscopy, and titration with HCl. The Nan was dosed with HCl to form (HCl)m..Nan/LiF(001), which was then irradiated by 640 nm laser-radiation to induce a charge-transfer (CT) reaction. Reaction-product atomic H(g) was observed leaving the surface, by two-color Rydberg-atom time-of-flight (TOF) spectroscopy. These H-atoms gave evidence of arising from the photoinduced harpooning reaction between the sodium clusters, Nan, on the substrate, and (HCl)m adsorbed on the Nan. The translational energy distribution, its vibrational structure, and the angular distribution of H(g) gave information regarding the harpooning event. Translationally and vibrationally excited HCl(g) was shown, by resonance-enhanced multiphoton ionization (REMPI), to be formed as an alternate product; by way of (HCl)m..Nan/LiF(001) + 602 nm-->(HCl)m - 1 Nan/LiF(001) + HCl(g)(v > or = 0).