Spectroscopic studies of neutral otoms in and on superfluid helium

超流氦中和超流氦上的中性原子的光谱研究

基本信息

批准号：
07102011
负责人：
YABUZAKI Tsutomu
金额：
$ 134.4万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Specially Promoted Research
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07102011/
关键词：
superfluid helium laser spectroscopy neutral atom mgnetic resonauce

项目摘要

A neutral atom implanted into liquid helium produces a bubble-like structure of helium, pushing out the surrounding helium due to the Pauli exclusion principle, This model of impurity atom in a self-produced bubble is called atomic bubble model. It is now known that this model explains well the general features of observed spectra. In the present work, we have focused particularly on the phenomena which cannot be explained by this model. For the ground state alkali atom, we observed the splitting of the exciting D2 spectra, which were found to be due to quadrupole oscillations caused by zero-point fluctuation. For the excited alkali atom, some new infrared spectra were observed, which were shifted considerably from the D lines. Comparing with calculated adiabatic potentials, we found that these lines infrared lines were from the molecules or clusters with several helium atoms sticking to the excited alkali atom. The Tm atoms implanted into liquid and solid helium were also studied. The optical transitions between the ground and the lower-lying states are due to those of the inner core electrons. There exist two outer electrons, which are expected to shield surrounding helium. We could succeed to observe several transitions of Tm atoms, the inner core transitions being extremely sharp due to this shielding. We succeeded to observe a weak magnetic dipole transition between two fine-structure levels and to measure precisely the lifetime of the upper metastable state. We have also studied gaseous alkali atoms interaction with the surface of liquid helium. The binding energy on the surface is very low and hence the interaction is mostly repulsive, Using the liquid helium film coated on the cell walls as an atomic reflector, we could realize, for the first time, a long-lived alkali vapor cell at a liquid helium temperature. Almost perfect spinpolarization of alkali atoms in the cell could be attained by using optical pumping techniques.

将中性原子注入液氦中，会产生氦的气泡状结构，由于泡利不相容原理，将周围的氦推出去，这种自产气泡中的杂质原子模型称为原子气泡模型。现在已知该模型很好地解释了观测到的光谱的一般特征。在目前的工作中，我们特别关注该模型无法解释的现象。对于基态碱原子，我们观察到了令人兴奋的D2光谱的分裂，发现这是由于零点波动引起的四极振荡。对于激发的碱原子，观察到一些新的红外光谱，这些光谱与 D 线有很大的偏移。与计算的绝热势相比，我们发现这些红外线来自于有几个氦原子粘附在激发态碱原子上的分子或团簇。还研究了注入液态和固态氦中的 Tm 原子。基态和低位态之间的光学跃迁是由内核电子的光学跃迁引起的。存在两个外层电子，预计它们会屏蔽周围的氦。我们可以成功地观察到 Tm 原子的几次跃迁，由于这种屏蔽，内核跃迁变得非常尖锐。我们成功地观察到了两个精细结构能级之间的弱磁偶极子跃迁，并精确测量了上亚稳态的寿命。我们还研究了气态碱原子与液氦表面的相互作用。表面的结合能非常低，因此相互作用大多是排斥的，利用电池壁上涂覆的液氦薄膜作为原子反射器，我们首次实现了长寿命的碱蒸气电池液氦温度。通过使用光泵浦技术可以实现电池中碱原子的几乎完美的自旋极化。