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.

植入液氦的中性原子会产生像氦气的气泡状结构，由于Pauli排除原理，推出了周围的氦气，在自生产的气泡中，这种杂质原子模型称为原子气泡模型。现在众所周知，该模型很好地解释了观察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，我们观察到令人兴奋的D2光谱的分裂，这是由于零点波动引起的四极振荡所致。对于激发的碱原子，观察到了一些新的红外光谱，这些光谱从D线大幅移动。与计算出的绝热电势相比，我们发现这些线红外线来自分子或簇，几个氦原子粘在激发的碱原子上。还研究了植入液体和固体氦的TM原子。地面和下层状态之间的光学转变是由于内核电子的光学转变。存在两个外电子，预计会屏蔽氦气周围。我们可以成功地观察到TM原子的几个过渡，由于这种屏蔽，内部核心过渡非常锋利。我们成功地观察了两个细胞结构水平之间的弱磁偶极转变，并精确地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。表面上的结合能非常低，因此相互作用主要是反击的，使用在细胞壁上涂有原子反射器的液体氦膜，我们可以首次意识到，在液态氦气温度下，长期存在的碱性蒸气池。通过使用光学泵送技术，可以实现细胞中碱原子的几乎完美的自旋极化。