Excitation spectrum of the A0+(5 3P1), B1(5 3P1)←X0+(5 1S0) transitions in the CdHe van der Waals molecule:: Spectroscopic characterization of the X0+, A0+, and B1 electronic energy states

The first observation of an excitation spectrum of the A0+(5 P-3(1)), B1(5 P-3(1))<--X0(+)(5 S-1(0)) transitions in the CdHe van der Waals molecule is reported. A continuous molecular-jet-expansion beam of CdHe seeded in helium was crossed with a pulsed-laser beam produced by a Nd:YAG laser-pumped-dye laser. The dye laser frequency was doubled using a KDP-C crystal and tuned to a frequency in the vicinity of the 5(3)P(1)<->5(1)S(0) resonance transition in atomic cadmium (lambda(res) approximate to 3262.0 Angstrom). The assignment of vibrational bands was obtained with the aid of rigorous computer simulation of the A0(+)X0(+) and B1 <-- X0(+) transitions. The analysis of the excitation spectrum yielded potential parameters of the molecule: D-e"(X0(+))=14.2 cm(-1), omega(e)"(X0(+))=9.6 cm(-1) omega(e)"x(e)"(X0(+))= 1.63 cm(-1) for the ground state, and D-e'(A0(+))=41.2 cm(-1), omega(e)'(A0(+))= 20.0 cm(-1) omega(e)'x(e)'(A0(+))= 2.4 cm(-1) as well as D-e'(B1)= 6.1 cm(-1) omega(e)'(B1)= 3.6 cm(-1), and omega(e)'x(e)'(B1)= 0.53 cm(-1) for the excited states. From a simulation procedure the differences between equilibrium cm internuclear separations Delta R=R-e"(X0(+))-R-e'(A0(+))= -1.50 Angstrom and Delta R=R-e"(X0(+))-R-e'(B1) =+0.12 Angstrom were also obtained. The results were subjected to the LeRoy-Bernstein method to evaluate the C-6/R-6 long-range potential parameters for the X0+ and A0+ energy states. (C) 1998 American Institute of Physics.