Creation Of Ultracold NaCs Polar Molecules By Photoassociation And Spectral Measurement Of C~3?~+state

In the past two decades,the preparation and related applications of ultracold molecules have attracted extensive attention of scientists.Compared with ultracold atoms,ultracold molecules have more freedom and richer vibrational energy level structures.For ultracold heteronuclear molecules,there is also a unique permanent dipole,which has important applications in the measurement of basic physical constants,ultracold chemistry,quantum computing and quantum simulation.Ultracold atomic photoassociation is a mainstream method for preparing ultracold polar molecules in the world,which has a low requirement for the initial ultracold atom temperature.In studying the photoassociation process of ultracold molecules,the precise measurement of the molecular constant of highly sensitive photoassociation spectroscopy is presented.The accurate construction and correction of potential energy curves of long range molecules and the study of molecular energy level structure in the near dissociation region are very important.In this paper,we use trap loss spectroscopy to measure the hyperfine structure spectra of ultracold Na Cs molecules.The potential energy curves of ultracold heteronuclear Na Cs molecules have been obtained by measuring the undetermined long range molecular coefficients in detail.The main work of this paper is to prepare ultracold Na Cs molecules by photoassociation technique in a double dark magneto-optical trap.The hyperfine structure spectra of c3?+ electronic states of ultracold Na Cs molecules are obtained by using highly sensitive trapping loss spectroscopy technique.At the same time,the spectral data are theoretically analyzed,the C6 coefficients of the long range molecule are fitted and calculated,and the potential energy curves of the long range Na Cs molecular states are obtained.The main work can be summarized as follows:1.A double dark magnetic-optical trap for alkali metal Na atoms and Cs atoms is constructed.The ultracold Na atoms and ultracold Cs atoms are simultaneously prepared by laser cooling and trapping technique,and the two kinds of atoms are prepared to the corresponding dark state,so as to further improve the density of ultracold Na atoms and ultracold Cs atoms.2.Ultracold Na Cs molecules are prepared by photoassociation.The excited ultracold Na Cs molecules are detected by trapping loss spectroscopy technique and the efficiency of the detection system is improved by phase locking technique.A series of hyperfine structure photoassociation spectra of c3?+ electronic states have been obtained.3.A series of hyperfine structure spectra of c3?+ electronic states of ultracold Na Cs molecules are analyzed.The spectral data are theoretically analyzed by semi-classical Le Roy-Bernstein model,and the values of the long-range molecular coefficients C6 and the potential energy curves of the long-range molecular states are fitted and calculated.The experimental results are compared with those obtained from other experiments and theoretical calculations.