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Atoms, Molecules and Ions in Superfluid Helium

超流氦中的原子、分子和离子

基本信息

批准号：
04554010
负责人：
YABUZAKI Tsutomu
金额：
$ 11.33万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04554010/
关键词：
superluid helium laser spectroscopy alkali atoms and molecules optical pumping magnetic resonance polarized hydrogen Bose condensation アルカリ原子光ポンピングアルカリ分子アルカリ土類原子

项目摘要

Neutral atoms, molecules and ions in superfluid helium have been attracted a great interest because of their unique optical features and energies considerably different from those in gases, solids, and ordinary liquids. For example, the valence electron of neutral atoms pushes our surrounding helium owing to the Pauli exclusion force and make a bubble-like structure. They have high potentiality to be applied to fundamental physics, because of their slow movement and a long spin relaxation time. However, there existed a serious experimental difficulty to implant these particles, particularly neutral atoms, in liquid. To remove this difficulty, we developed at first the laser-sputtering methods and succeeded to implant many kinds of particles at high density in superfluid helium. We could succeeded to implant alkali atoms and molecules for the first time and to observe the excitation spectra and emission spectra. The shifts and broadening of observed spectra were found to be explained theoretically by using the spherical atomic bubble model. We found the existence of quadrupole type oscillation of the bubble shape, from the observed D_2 excitation spectra composed of splitted two components. In addition to laser spectroscopy, we made optical pumping experiment with a circularly polarized laser beam and neraly 100% polarization could be achieved for both electron and nuclear spins. The magnetic resonances and hyperfine resonances could also be observed by optical means and the g-values and hyperfine constants could be measured. Furthermore, we studied two dimentional polarized hydrogen trapped on the surface of superfluid helium, and we could obtained the number density very closed to the critical value for the Bose condensation.

超流氦中的中性原子、分子和离子因其独特的光学特征和能量与气体、固体和普通液体中的显着不同而引起了人们的极大兴趣。例如，中性原子的价电子由于泡利排斥力而推动周围的氦并形成气泡状结构。由于其缓慢的运动和较长的自旋弛豫时间，它们具有应用于基础物理学的巨大潜力。然而，将这些粒子，特别是中性原子植入液体中存在严重的实验困难。为了解决这个困难，我们首先开发了激光溅射方法，并成功地在超流氦中高密度地注入了多种粒子。我们首次成功地注入碱金属原子和分子并观察激发光谱和发射光谱。发现观察到的光谱的移动和展宽可以通过使用球形原子泡模型从理论上解释。从观测到的由分裂的两个分量组成的D_2激发光谱中，我们发现气泡形状存在四极型振荡。除了激光光谱之外，我们还用圆偏振激光束进行了光泵浦实验，电子和核自旋几乎可以实现 100% 偏振。还可以通过光学手段观察磁共振和超精细共振，并且可以测量g值和超精细常数。此外，我们研究了超流氦表面捕获的二维极化氢，得到了非常接近玻色凝聚临界值的数密度。