提出并演示了一种光泵预选态的原子光谱测量方法, 并对Ba原子的6s5d 3D态与6p5d 3F态的超精细结构及该跃迁的同位素移动进行了直接测量。 首先利用791 nm的激光激发Ba原子特定同位素及特定超精细结构的6s6s 1S0→6s6p 3P1跃迁, 并利用6s6p 3P1→6s5d 3D2的自发辐射有选择地分别将这些同位素制备到6s5d 3D2态不同的超精细能级上, 再用778 nm的激光扫出对应的6s5d 3D2→6p5d 3F2跃迁的荧光光谱, 通过这几组光谱之间的对比直接实现了对22条超精细谱线的认定和归属, 从而得到了135Ba和137Ba的6s5d 3D2能级与6p5d 3F2能级的超精细结构常数及该跃迁的同位素移动。

In the present experiments, a new method of atomic spectral measurement using states optical pre-selection was proposed and demonstrated, and the measurement of hyperfine-structures and isotope shifts in the 6s5d 3D→6p5d 3F transitions of Ba I was taken as an example. A 791 nm laser was used to excite the different hyperfine transitions 6s6s 1S0→6s6p 3P1 for different isotopes of barium and different hyperfine energy-levels of 6s5d 3D2 for these isotopes were populated by the 6s6p 3P1→6s5d 3D2 spontaneous radiations, then the corresponding fluorescence spectra of 6s5d 3D2→6p5d 3F2 transitions excited by another 778 nm laser were recorded. Comparing of these spectra, 22 lines were recognized and the hyperfine-structure constants of 6s5d 3D2 and 6p5d 3F2 of 135Ba and 137Ba were evaluated consequently while the isotope shifts of these transitions were also determined.