Short-range characterization of the MeAr (Me = Zn, Cd) ground-state potentials from fluorescence spectra

First-time observed D1(1Pi)(v'-10) --> X0(+)((1)Sigma) fluorescence in ZnAr, and A0(+)((3)Pi)(v'-4) --> X0(+) and D1((1)Pi)(v'=7, 8) --> X0(+) fluorescence in CdAr van der Waals (vdW) molecules were produced in a continuous supersonic molecular beam crossed with a pulsed dye-laser beam, following excitation of single vibronic levels. The dispersed fluorescence spectra displayed characteristic Condon internal diffraction (CID) patterns consisting of bound-free, reflection type, continuous spectra, and, in certain cases, bound-bound discrete features. An analysis of the A0(+) --> X0(+) and D1 --> X0(+) bound-bound spectra indicates that Morse functions are adequate representations of the X0(+) potential energy (PE) curves below their dissociation limits. In simulation of the A0(+) --> X0(+) and D1 --> X0(+) bound-free spectra, the Morse, Lennard-Jones L-J(n - 6), and Maitland-Smith M-S(n(0), n(1)) functions were tested, and the respective M-S(11.3, 9.0) and M-S(10.6, 7.0) potentials were found to be good representations for the repulsive walls of the X0(+) PE curves of ZnAr and CdAr, respectively, over the short range, R = 2.45-4.38 Angstrom (ZnAr) and R = 2.85-4.31 Angstrom (CdAr), of internuclear separations. (C) 2002 Elsevier Science (USA).