Experimental studies of double-well potential energy curves theoretically implied as the representation of the lowest molecular Rydberg states of CdRG (RG = Ne,Ar,Kr) diatomic clusters

Abstract

The lowest Rydberg state El ( 3 E + ) of the CdNe CdAr and CdKr van der Waals complex has been investigated by an optical-optical double resonans (OODR). Two electronic states: AO + (5 3 P 1 ) and B1 (5 3 P 1 ) have been used as intermediates for probing the final E1(6 3 S 1 ) state. We have measured the bound-bound laser excitation spectra of the E1 2 AO + transition which correspond to the first observation of the bound CdNe/CdAr/CdKr complexes in the El state. By means of Birge-Sponer (BS) linear plot of the v'-progression we estimated the spectroscopical parameters of the potential well of the Cd(6 3 S 1 )-Ne(2 1 S 0 )/Ar (3 1 S 0 )/Kr(4 1 S 0 ) interactions. On the other hand in the excitation spectrum of the El 2 Bl transition we observed the characteristic nodal structure of a bound-free absorption which can be elucidated by the Franck-Condon (FC) projection of vibrational wave-function of the Bl state onto the hump of the E- state potential as it was predicted by ab initio calculations of Czuchaj and Stoll. Assuming Morse function as an adequate approximation of the inner El potential well we simulated the observed bound-bound spectra and hence we obtained some additional information regarding the location of the potential well minimum (R e ). By the use of B1 state as an intermediate we were also able to observe some bound-bound spectra related to a second (shallow) minimum in the potential energy curve and to evaluate its potential parameters. Simple energy considerations makes also possible an evaluation of the height of potential barriers predicted theoretically in the potential energy curves of the E1 state. Generally our results are in a reasonable agreement with the ab initio calculated results.