Experimental interrogation of the multidimensional He plus ICl(E, v†) and He+ICl(β, v†) intermolecular potential energy surfaces

Resonant two-photon excitation of the T- shaped and linear He center dot center dot center dot I(35)Cl(X, v ''= 0) complexes is used to access the intermolecular vibrational levels bound within the He+ICl(beta,v(dagger)=0-2) and He+ICl(beta, v(dagger) = 11,12) intermolecular potentials. The excitation utilizes different metastable intermolecular vibrational levels within the He+ICl(A, v ' = 15) and He+ICl(B, v ' = 2,3) potentials to access levels with varying intermolecular vibrational excitation in the ion- pair states. In addition to providing data revealing properties of the He+ICl(E, v(dagger) = 15) and He+ICl(B, v(dagger) = 2,3) potentials, the transition energies of the observed features permit the relative binding energies of the T- shaped and linear ground-state He center dot center dot center dot ICl(X, v ''= 0) conformers to be accurately measured. The binding energies of the T- shaped and linear He center dot center dot center dot I(35)Cl(X, v '' = 0) conformers are 16.6(3) and 22.0(2) cm(-1), respectively. These values and the observed transition energies are then used to set the binding energies of the T-shaped He center dot center dot center dot I(35)Cl complexes in the He+ ICl(A, v ' = 15), He+ICl(B, v ' = 3), He +ICl(beta, v(dagger) = 1), and He+ICl(E, v(dagger) = 12) potentials as 13.4(3), 13.3(3), 41(1), and 39.2(4) cm(-1), respectively. Nonadiabatic coupling between specific intermolecular vibrational levels within the He+ICl(beta, v(dagger)) state and the ICl (D ', v(dagger) =12) molecular state is observed. (C) 2008 American Institute of Physics.