Fig. 1. Experimental scheme and laser ablation data^[91]. (a) Scheme for the production of BaF molecule via laser ablation; (b) absorption signal; (c) normalizaiton and fit of the absorption signal; (d) the generated molecular number versus the output power of the ablation laser; (e) the dependence of the molecular number on the ablating times when successively ablating a position of the target. The repetition rate of the laser pulse is 2 Hz and the flow rate of the He gas is 5 sccm. 激光消融示意图及实验数据^[91] 　(a)激光消融产生BaF分子示意图; (b)分子吸收信号, 消融激光在t = 0 ms时打开; (c)对吸收信号做归一化处理和拟合; (d)吸收信号与消融激光输出功率的关系; (e)当消融靶材上固定某一位置处, 消融激光轰击次数越多, 分子吸收信号越差. 消融脉冲频率为2 Hz, He气速流为5 sccm

Fig. 2. Molecular distribution at different states^[91]. (a) Theoretic calculation of the rotational distribution for different temperatures; (b) experimental data for different rotational populations. All data are normalized with N = 0 population; (c) theoretic calculation of the vibrational distribution; (d) experimental absorption signal for v = 0 and v = 1 molecules from laser ablation. 分子在不同能级的布居分布^[91] 　(a)理论上根据玻尔兹曼分布计算不同温度下各个转动态上分子布居数的比例; (b)转动态温度的测量与拟合. 这里各个转动态的布居数均以测量的 态的布居数进行归一化; (c) 4 K和300 K温度下振动态布居数的分布; (d)实验测量的对 (蓝色)和 (红色)跃迁的吸收信号

Fig. 3. The energy levels of BaF and dark state mixing^[98].(a) Scheme for closing the vibrational levels; (b) scheme for closing the rotational and hyperfine dark states; (c) sideband modulation via an EOM to generate the four frequency bands to cover the four hyperfine sublevels; (d) LIF enhancement via introducing the sideband modulation; (e) LIF enhancement by introducing the polarization modulation; (f) LIF enhancement when adding the v = 1 repump laser. BaF能级示意图和暗态消除方案^[98] 　(a)振动态能级的闭合方案, 增加896 nm和898 nm两个再泵浦激光; (b)转动态能级的闭合及超精细能级分裂示意图; (c)利用EOM调制产生的4个频率边带, 图中是调制后的激光用法珀腔测量的信号; (d)引入边带调制后荧光信号的增强; (e)进行偏振调制后荧光信号的增强; (f)增加 v = 1再泵浦光后荧光信号的增强

Fig. 4. Deflection of the BaF molecular beam with the quasi cycling transitions^[98]. Images are given on the x-z plane of the (a) Deflected and (b) unperturbed molecular beams, respectively. The x direction reflects the width of the probe laser beam, while the z direction gives the transverse profile of the molecular beam. (c) integrated signal of the images in (a) and (b) along the x axis. The black and red lines are Gaussian fits to the unperturbed (light gray) and deflected (light orange) signal, which gives the revival rate of 80%. (d) normalized plot of the signals in (c) to clearly show the deflection effect. (e)deflection distance as a function of the number of the deflection beam, yielding the dependence of the scattering photon number on the interaction time. The red solid line is a linear fit to the measured data, illustrating that the photon scattered linearly increases with the interaction time. The black dashed line is the numerical prediction of the scattering from the 4+25 MLRE model with the switching scheme. 分子束偏转^[98]. CCD在x-z平面成像　(a)和(b)分别对应在相互作用区域有偏转光和没有偏转光时分子束的形状, (c)中给出沿 方向分别对(a)和(b)做积分后得到信号. 黑色和红色实线分别为两个信号的高斯拟合. (d)对(c)中的信号分别做归一化, 以清晰地展示偏转效果. (e)偏转距离与偏转光束数量之间的关系, 相应地, 可以推出散射光子数与相互作用时间间的关系. 红色实线为对测量结果的线性拟合. 黑色虚线为根据4+25能级速率方程模型计算得到的散射光子数与相互作用时间的关系