The structure of the lowest electronic Rydberg state of CdAr complex determined by laser double resonance method in a supersonic jet-expansion beam

摘要

The lowest El((3)Sigma(+) ') Rydberg state of the CdAr van der Waals (vdW) complex was investigated by means of an optical-optical double resonance (OODR) method of laser spectroscopy in conjunction with a free jet-expansion molecular beam. Two dye lasers were employed for the two-step excitation. The A0(+) ((3)Pi(+) ') and Bl((3)Sigma(+)) states were used as intermediates in the excitation process from the X0(+)((1)Sigma(+)) ground state. Two types of bound-bound excitation spectra of the El <--A0(+) and El <--Bl transitions were recorded indicating the existence of two, well defined minima in the El-state potential energy (PE) curve. First, considerably deep, with the well depth of D-e (El(2)) = 1309.0 cm(-1) and second, separated by a positive PE barrier, with D-e (El(2)) = 24.2 cm(-1). Combination of bound-bound and first-time observed bound-free excitation spectra enabled a complete determination of the spectroscopical parameters of the PE curve of the El-Rydberg state, the height of the PE barrier and its approximate location. In the excitation spectra of the El <-- Bl transition, a nodal structure of the bound-free transitions was observed and elucidated by a projection of the Bl-state vibrational wave-functions onto the El -state potential barrier and/or onto the repulsive part of the El-state PE curve. The experimental results of our investigation coincides well with recently published results of ab initio calculation of Czuchaj and co-workers (C) 2002 Elsevier B.V. All rights reserved. [References: 24]