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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.

注入液氦的中性原子会产生一个气泡状的氦结构，由于泡利不相容原理，将周围的氦挤出，这种杂质原子在自生气泡中的模型称为原子泡模型。现在我们知道，这个模型很好地解释了观测光谱的一般特征。在目前的工作中，我们特别关注的现象，不能用这个模型来解释。对于基态碱原子，我们观察到激发态D2谱的分裂，发现这是由于零点涨落引起的四极振荡。对于激发态碱金属原子，观察到一些新的红外光谱，这些光谱与D线有很大的位移。通过与绝热势计算值的比较，发现这些红外线是由多个氦原子与激发态碱金属原子结合形成的分子或团簇产生的。还研究了Tm原子注入液态氦和固态氦的情况。基态和低位态之间的光学跃迁是由于内核电子的光学跃迁造成的。存在两个外层电子，它们被期望屏蔽周围的氦。我们可以成功地观察到Tm原子的几个跃迁，由于这种屏蔽，内核跃迁非常尖锐。我们成功地观察到两个精细结构能级之间的弱磁偶极跃迁，并精确测量了上亚稳态的寿命。我们还研究了气态碱金属原子与液氦表面的相互作用。由于表面的结合能很低，相互作用主要是排斥作用，利用涂在池壁上的液氦膜作为原子反射器，我们首次实现了液氦温度下长寿命的碱金属蒸气池。利用光抽运技术，可以使池中碱金属原子获得近乎完美的自旋极化。