Ca+-Ar-2 complexes: linear or bent?

Ca+-Ar-2 complexes are investigated with mass-selected photo dissociation s pectroscopy and with high-level ab initio calculations. Theory finds two mi nima with comparable energies for the ground state, a linear Ar-Ca+-Ar stru cture and a C-2v, Ca+-Ar-2 structure with a significant argon dimer interac tion. The latter is computed to be slightly lower in energy. Electronic spe ctroscopy finds a sharp spectrum near the forbidden Ca+(D-2-S-2) atomic int erval. Two vibronic progressions are assigned that have significantly diffe rent linewidths. Analysis of the spectrum establishes that the complex is m ost likely linear. (C) 2001 Elsevier Science B.V. All rights reserved.