PHOTOINDUCED REACTION IN COLLINEAR ALIGNED MG+-CO2 COMPLEXES

Mg+-CO2 ion-molecule complexes are produced in a pulsed nozzle molecular beam cluster source. Spectroscopic studies, in coordination with ab initio calculations, confirm that these complexes are linear and that the bonding is primarily electrostatic (ion-quadrupole forces). Excited-state energies and the symmetries of the orbitals involved am well characterized. Photoexcitation of these complexes near the 2S --> 2P atomic resonance line results in both simple cleavage of the electrostatic bond and a metal ion insertion reaction, producing the products Mg+ + CO2 and MgO+ + CO, respectively. The reactive channel is sharply wavelength dependent and occurs only in an excited state which has the Mg+ p orbital aligned on the internuclear axis.