Investigation of the rare-abundant naturally-occurring long-lived radioisotopes by nuclear laser spectroscopy

稀有丰富的自然存在的长寿命放射性同位素，如^<50>V,^<138>La,^<176>Lu是接近中子幻数的原子核。这样的原子核不仅对核物理学，而且对年代测定和天体物理学都有特别的意义。在这个项目中，我们进行了核激光光谱学来了解这类原子核的超精细结构、电荷分布和核矩。利用我们开发的高分辨率二极管激光光谱装置，我们将测量范围扩展到轻元素，如^<89>Y，并确定了其超精细常数和g因子。研究了与宇称不守恒有关的斯塔克效应。在795 nm处观察到Rb 5s^2S_<1/2>→5p ^2P_<1/2>跃迁和Cs 6s^2S_<1/2>→6p^2P_<3/2>跃迁的Stark光谱，电场变化高达40 keV/cm，并推导出Rb和Cs的标量极化率和张量极化率。特别是，为了测量稀有丰富的天然放射性同位素，我们将倍频系统与二极管激光器相结合，获得了高达100 μW的高分辨率紫外激光源。利用高分辨率实验装置和紫外激光源，我们成功地在紫外区进行了^<27>Al的高分辨率核激光光谱分析。首次测定了^<27>Al的4个原子能级的超精细常数，包括基态。利用强光学紫外跃迁对自然存在的稀有长寿命原子核^<176>Lu进行了核激光光谱分析，得到了^<176>Lu和^<175>Lu的超精细常数，并得到了^<176-175>Lu的同位素位移。我们的一些研究结果已被报道，其中大部分将在其他地方发表。

The rare-abundant naturally-occurring long-lived radioisotopes, such as ^<50>V,^<138>La,^<176>Lu are the nuclei near the neutron magic numbers. Such nuclei are of particularly interests not only for nuclear physics but for dating and astrophysics. In this project, we carried out nuclear laser spectroscopy in order to understand hyperfine structures, charge distribution and nuclear moments of such nuclei. Using our developed high-resolution diode-laser spectroscopic setup, we expanded our measurements to light elements, such as ^<89>Y, and determined its hyperfine constants and g factors. The Stark effect, related to the parity non-conservation, was also investigated. Stark spectra were observed for the Rb 5s^2S_<1/2>→5p ^2P_<1/2> transition at 795 nm and for the Cs 6s^2S_<1/2>→6p^2P_<3/2> transition at 852 nm with the change of the electric field up to 40 keV/cm, and scalar and tensor polarizabilities were derived for Rb and Cs. In particular, in order to measure the rare-abundant naturally-occurring radioisotopes, we combined a frequency-doubling system with the diode laser, and a high-resolution UV laser source, up to 100 μW, was obtained. Using the high-resolution experimental setup together with the UV laser source, we succeeded in performing high-resolution nuclear laser spectroscopy of ^<27>Al in the UV region. Hyperfine constants of 4 atomic levels of ^<27>Al, included the ground state, were determined for the first time. Nuclear laser spectroscopy of the rare-abundant naturally-occurring long-lived nucleus ^<176>Lu was performed using the strong optical UV transition, and hyperfine constants of ^<176>Lu and ^<175>Lu were derived and isotope shifts of ^<176-175>Lu were obtained. Some of our results have been reported and most of them will be published elsewhere.