High Resolution Laser Spectroscopy Of The Excited States Of Rb₂ And Cs₂

The study on the electronic excited states of diatomic alkali metal molecules not only plays an important role in atom?molecule?cooling,chemical reaction dynamics,precision measurement and coherent control etc.,but also offers a great sample for molecular spectroscopy.The main work of this thesis focuses on the high resolution laser spectroscopy on the electronic excited states of rubidium dimmer?Rb₂?using perturbation facilitated optical-optical double resonance?PFOODR?technique.Continuous infrared semiconductor diode laser and Ti:Sapphire laser were used in a pump-probe experimental setup,and high resolution Fourier Transform Spectrometer?BOMEM DA and SPEX?were used to record the fluorescence from high excited states to the lower states.The Rb₂ 2³?_0g,4¹?_g⁺and 3¹?_g⁺states have been systematically studied for the first time,including:thousands of ro-vibrational energy levels term values were detected;molecular constants were obtained by analyzing these energy levels term values;the potential minima T_e of the 2³?_0g,4¹?_g⁺and 3¹?_g⁺states are 20284.5 cm^-1,19973.0429 cm^-1,19244.2007 cm^-1,respectively;and their equilibrium inter nuclear distance R_e are 5.5458?,4.9151?,5.4124?;the experimental energy curves were constructed matching Rydberg-Klein-Rees?RKR?function with the calculated energy curves;perturbation between the2³?_0g and 4¹?_g⁺states due to the spin-orbit interaction along with the electrostatic perturbation between the 4¹?_g⁺and 3¹?_g⁺states were detected.Besides,the fleorescence spectrum from the 2³?_0g state to the ground triplet a³?_u⁺state was recorded and analyzed,the term values of dozens of v-J energy levels,R_e,T_e,and energy curve of the triplet ground state were obtained.Using the perturbation between intermediate states A¹?_u^+b3?_u,twelve ro-vibrational energy levels of the ⁸⁵Rb₂ b³?_1u state have been observed.Using the new observed levels as intermediate window levels,dozens of transitions in to the⁸⁵Rb₂ 2³?_1g upper state v-J levels have been recorded.The average term value difference between the?=1 and?=0 components of the ⁸⁵Rb₂ 2³?_g levels with the same rotational quantum number is approximately 83.1±0.3 cm^-1,which proves that the 2³?_g state tends to belong to Hund's case?a?and it has a spin-orbit splitting of A=83.1±0.3 cm^-1.Another part of this thesis concentrates on the high sensitive photoassociation?PA?spectroscopy study of ultracold cesium dimmer?Cs₂?.Ultracold Cs₂ PA spectra have been obtained by directly modulating the frequency of the trapping lasers of a magneto-optical trap.The spectral range was extended to the red detuning of 112 cm^-1 below the 6S_1/2+6P_3/2dissociation limit and dozens of lower vibrational levels along with hundreds of rotational levels of the 0_g^-,0_u⁺,1_g long-range states at the asymptotes 6S_1/2+6P_1/2 and 6S_1/2+6P_3/2 were observed.The available set of the binding energies of all the six states has been analyzed simultaneously within a framework of the LeRoy-Bernstein near dissociation theory,which gives the unique atomic-related parameter c₃ governing the long-range properties of all the Cs₂states is 10.29±0.05 a.u..