Precision Cesium Atomic And Molecular Spectroscopy

Precision spectroscopy is one of the important means of acquiring basic knowledge ofmaterial structure and exploring the physical laws of microscopic world. Precisionspectroscopy have widely applications and great significance in determining the basicphysical constants and accurate calibration of time and frequency. Periodic pulse emitted fromfemtosecond laser corresponds to the uniform distribution of the frequency comb in thefrequency domain, combined with the expanding spectrum application of photonic crystalfiber, femtosecond optical frequency comb become the next generation of optical frequencymeasurement techniques. Femtosecond optical frequency comb combined with the interactionof ultracold atoms and molecules, can carry out the coherent control of ultracold atoms andmolecules, with higher time-resolution and higher precision of spectrum to understandmatter’s internal energy transfer and information transmission process in microscopic world,which provides new concepts and new methods for the research of precision spectroscopy andquantum control.In this paper, we produce ultracold cesium atoms with high-density by using the lasercooling technology in magneto optical trap, prepare ultracold cesium molecules by usingphotoassociation technique, and obtain vibrational spectrum of cesium molecular withhigh-resolution. Combining femtosecond optical frequency comb with cesium atoms, weobtain the high-resolution two-photon spectroscopy of cesium.In this paper, the main work is as follows:1. We obtain the ultracold samples of cesium by using laser cooling and trappingtechnique, the temperature of atoms is about200uK, the density is about1011/cm3. Then, weproduce ultracold cesium molecular by the method of photoassociation(PA) and obtainhigh-precision PA spectrum of cesium under6S1/2+6P1/2dissociation limit, including threelong-range excited states—0u、0gand1gstate.2. In the experiment, we analyse the power effect of vibrational spectrum and the line-width in different power of PA laser. Based on the vibrational spectrum of the0ustateof v=214,215,216, we calculate the rotational constant Bv=0.0015cm-1，0.00175cm-1，0.00242cm-1.3. Selecting filters to excite cesium atoms to8S1/2,9S1/2and7D3/2states, we investigatetwo-photon frequency comb spectrum with high-resolution.4. We calculate the hyperfine coupling constants of8S1/2,9S1/2,7D3/2excited states asfollows: A8S=219.137(11)MHz, A9S=110.150(13)MHz, A7D=7.38(19)MHz, B7D=-0.15(21)MHz. The absolute centroid frequency of6S1/2�'8S1/2,9S1/2,7D3/2is729009798.80(17)MHz,806761363.96(11)MHz,780894762.595(23)MHz, respectively.