Direct measurement of the binding energy of the linear He•••I35,37Cl(X) isotopomers

Two color, pump-probe action spectra were recorded by tuning an excitation laser through the ICl B-X, 2 0 spectral region and monitoring the fluorescence induced by a probe laser, which was fixed on either the (ICl)-Cl-35 or the (ICl)-Cl-37 E-B, 13-2 bandhead. A continuum signal is observed above a discrete energy in each of the action spectra that is attributed to bound-free transitions of the He...(ICl)-Cl-35,37 complexes with preferred linear equilibrium geometries. The shifts of the onsets of the continuum signals from the transition energies of the respective PCl and (ICl)-Cl-35 B-X, 2-0 band origins correspond to ground state binding energies of 22.3(1.2) and 22.5(1.1) cm(-1) for the linear He...(ICl)-Cl-35(X,v" = 0) and He...(ICl)-Cl-37(X,v" = 0) isotopomers. (C) 2003 Elsevier B.V. All rights reserved.