Experimental studies of the NaCs 12(0+) [71Σ+] state: Spin-orbit and non-adiabatic interactions and quantum interference in the 12(0+) [71Σ+] and 11(0+) [53Π] emission spectra

Abstract

We present results from experimental studies of the 11(0) and 12(0) electronic states of the NaCs molecule. An optical-optical double resonance method is used to obtain Doppler-free excitation spectra. Selected data from the 11(0) and 12(0) high-lying electronic states are used to obtain Rydberg-Klein-Rees and Inverse Perturbation Approach potential energy curves. Interactions between these two electronic states are evident in the patterns observed in the bound-bound and bound-free fluorescence spectra. A model, based on two separate interaction mechanisms, is presented to describe how the wavefunctions of the two states mix. The electronic parts of the wavefunctions interact via spin-orbit coupling, while the individual rotation-vibration levels interact via a second mechanism, which is likely to be non-adiabatic coupling. A modified version of the BCONT program was used to simulate resolved fluorescence from both upper states. Parameters of the model that describe the two interaction mechanisms were varied until simulations were able to adequately reproduce experimental spectra.

Observation of photoassociation of ultracold sodium and cesium at the asymptote Na (3S1/2) + Cs (6P1/2)

“…36 Due to these characteristics, a number of spectroscopic investigations on NaCs have been performed in hot molecular samples during the recent years, and various states, i.e., the 3 1 Π, A 1 Σ, b 3 Π, X 1 Σ + , a 3 Σ + , 5 3 Π 0 , and 12(0 + ) states of NaCs, have been analyzed. 35,[37][38][39][40][41] Nevertheless, at a lower temperature far below 1 mK, the ultracold polar NaCs molecules demonstrate their advantages with enhanced accuracy and resolution. By using the PA approach, the ultracold NaCs molecules were created by Bigelow and co-workers for the first time.…”