本项目的主要研究内容：(1)选择一种适合做分子激光冷却实验的分子（候选分子氟化镁或者氢化铍），研究分子准闭合的能级结构和分子从X2Σ态跃迁到A2П态转动光谱和精细能级光谱。(2)设计并制备一束具有高束流、低内态和外态温度的分子束，作为分子激光冷却的束源；（3）消除分子的暗态，实现在优化的激光失谐和磁场强度条件下，分子束横向多普勒冷却，对应冷却温度小于5mK；（4）采用自发辐射力减速分子束纵向速度，平动速度小于50m/s；（5）研究并比较分子束的横向共振辐射力偏转和受激辐射力偏转，探索采用双色激光驻波场的受激辐射力来快速减速分子束的纵向速度，为实现分子在磁光阱中的二维和三维激光冷却与囚禁提供新的技术方案，也为实现产生超冷的化学稳定分子样品的研究奠定实验基础，可望产生温度微开量级的冷分子样品，并为在凝聚态物质中的量子模拟、量子计算、精密测量和冷碰撞等方面的应用提供理论与实验依据。

The main research content of this project: (1) to choose a candidate molecule (MgF or BeH) for laser cooling experiment, and measure the rotational and hyperfine structure for X2Σ and A2П of MgF or BeH. (2) to design and construct a low-temperature molecular beam source with high flux, low internal temperature and low translational temperature, it can be used as the beam source of laser cooling of molecule;(3) to eliminate the molecular dark state, and realize the transverse Doppler cooling of the MgF or BeH molecular beam under the optimal laser detuning and magnetic field intensity with cooling temperature less than 5mK. (4) to realize longitudinal velocity deceleration of molecular beam with the spontaneous radiation forces with slowed velocity less than 50m/s. (5) to study and compare the transverse deflection of the molecular beam by the radiative force and stimulated force, and explore the rapid deceleration of molecular beam with the optical bichromatic forces, support new technological scheme for the 2D and 3D laser cooling and trapping of molecule in Magneto-Optical Trap, establish the experimental basis for the generation of ultracold chemistry-stable molecules, and it is anticipated that ultracold molecules attractive candidates with the temperature of microKelvin has some potential applications in quantum simulations of condensed-matter systems, quantum computation, precision measurement, and cold collision, and so on.