Bichromatic Photoassociation Spectroscopy for the Determination of Rotational Constants of Cs2 0 u + Long-Range State below the 6S1/2 + 6P1/2 Asymptote.

Jizhou Wu,Yuqing Li,Peng Li,Vladimir B Sovkov,Jie Ma,Wenliang Liu

doi:10.3390/molecules25173963

Abstract

This article demonstrates new observation of the high-resolution ro-vibrational bichromatic photoassociation spectra (BPAS) of Cs2 in the long-range state below the asymptotes 6S1/2 + 6P1/2. By combining with a modulation spectroscopic technique, precise references of the frequency differences have been engineered through the BPAS, with which the rotational constants of low-lying vibrational levels of the Cs2 long-range state have been accurately determined by fitting the frequency differences to the non-rigid-rotor model. The rotational constants for the newly observed seven ro-vibrational levels are summarized and disagreement for the level ῦ = 498 is clarified. The rotational constants of different vibrational levels demonstrate strong perturbations of the related energy structures. A simple analysis is performed and shows good agreement with experimental results.

Highlights

During trecent decades, quantum science and technologies have reached tremendous achievements benefiting from the ultracold atoms and molecules with a temperature extremely lower than1 mK [1,2], under which the inter-particle collisions are fully quantum-mechanical and highly sensitive to long-range interactions
Ultracold molecules prepared by PA are characterized by small binding energies as the molecules are mostly formed in the near dissociation region
The bichromatic photoassociation spectra (BPAS) for specific vibrational levels in the Cs2 0u+ long-range state near the dissociation limit 6S1/2 + 6P1/2 are newly detected, with which the rotational constants are obtained with a high accuracy

Summary

Introduction

Quantum science and technologies have reached tremendous achievements benefiting from the ultracold atoms and molecules with a temperature extremely lower than. Pillet’s research group realized the formation of the ultracold Cs2 ground state molecules via the PA, obtained the PAS, and estimated the rotational constants for the vibrational levels of the 0u+ and 1g states ranged from −5 cm−1 to −40 cm−1 relative to the Cs2 6S1/2 + 6P3/2 dissociation limit [25]. Efforts have been made to further extend the PAS detection range, both to the high-lying molecular vibrational levels within the extremely dense states and to the lower-lying levels that are largely red detuned against the 6S1/2 + 6P3/2 [15,18] 6S1/2 + 6P1/2 [35] asymptotes. The BPAS for specific vibrational levels in the Cs2 0u+ long-range state near the dissociation limit 6S1/2 + 6P1/2 are newly detected, with which the rotational constants are obtained with a high accuracy. Our results provide a framework for future works exploring the precise potential energy curves of the long-range states

Experimental Details

Results and Discussion

Six typical

Conclusions