Theoretical Calculation Of Spectral Properties For Low Excited Electronic States Of SrCl Molecule

Cold molecules research and analysis has been one of the most frontier subjects in the field of atom and molecule physics.Because of the complex vibrational energy levels and rotational energy levels of molecules,it is necessary to select a molecule with a quasi closed level system so that laser cooling of atoms molecule can be realized which is identical to the case of atomic laser cooling.Based on the background of laser cooling SrCl molecule,the main methodology and results are as follows:(1)RKR method is adopted to calculate the potential energy curves of both the ground electronic state X~2?~+ and the first excited electronic state A~2? with the experimental spectroscopic constants,as well as the Franck-Condon factor of A~2?-X~2?~+ transition.(2)With the rationale of ab initio method,calculation of the potential energy curves of seven ?-S states for two dissociation limites of SrCl molecule can be obtained.The spectroscopic constants for the five low-lying electronic states are fitted and the calculated results are in good agreement with the experimental data.By the vibration wave function,the Franck-Condon factor of A~2?-X~2?~+ transition is computed.The calculated results turn to be close to those of RKR method.Based on the transition dipole moments obtained in the calculation process,the lower radiative lifetimes of A~2?-X~2?~+ transition and Einstein spontaneous emission coefficient can be both obtained.(3)The Franck-Condon factor within the ground vibrational energy levels of A~2?-X~2?~+ transition for SrCl molecule is 0.96,which indicates that the transition between these two levels constitutes a quasi closed cycle.It is shown that SrCl molecule is a suitable candidate for laser cooling.In the end,the cooling scheme of SrCl molecule is provided.