Creation of 'Alkali-Helium' miticisle and clusters, and laser spectroscopy

在低温下，原子态的动力学可以用光学方法观察到，它是由周围粒子的热运动引起的非相干摄动。原子相干性的信息有助于研究量子力学的基本概念。通过观察内电子壳层间的光学跃迁，研究了液体氦和固体氦中的铥原子。亚稳态是通过在固体氦中捕获高密度的铥原子来检测的。这一结果使固体氦原子适用于原子常数的精确测量。我们也可以用激光冷却技术捕获原子。由于冷却原子的高密度，原子间相互作用会影响光跃迁的能量或相位，这是精确原子钟需要研究的问题。我们将卤化碱晶体中的O^-_视为高密度分子，并以高时间和光谱分辨率观测其发射。值得注意的现象是来自高密度O^-_薄层的超荧光。由于光的能量比与周围原子相互作用的能量大得多，因此在低温下对原子和分子进行光学探测很容易改变它们的电子状态和结构。为了对原子状态进行无损观测，我们在激光的基础上加入了射频场。高分辨率的磁共振使我们能够分辨原子和团簇的种类。三维磁共振成像（MRI）告诉我们原子在低温下的分布。目前我们可以观察到氦气体中Cs的磁共振和二维MRI。通过光抽运和检测，对图像进行了灵敏的观测。从抽运到检测的延迟时间，我们可以看到极化Cs的扩散。在未来，我们将测量宽温度范围内的扩散常数，以及稀有气体原子在低温下的核磁共振。

The dynamics of atomic state, which is perturbed incoherently by thermal motion of surrounding particles, can be optically observed at low temperature. The information of atomic coherence is helpful to study basic concepts of quantum mechanics.Thulium atom in liquid and solid helium is studied by observing the optical transition between inner electronic shells. The metastable state is detected by trapping thulium atoms with high density in solid helium. This result makes atom in solid helium applicable to accurate measurement of atomic constants. We can also trap atoms with the technique of laser cooling. Because of high density of cooled atom, the energy or phase of optical transition is affected by the inter-atomic interactions which should be studied for accurate atomic clock. We treat O^-_ in alkali halide crystals as high density molecules, and observe the emission with high temporal and spectral resolution. Remarkable phenomena is superfluorescence from the high density O^-_ thin layr.The optical detection of atoms and molecules at low temperature is easy to change their electronic state and structure, because the energy of light is much larger than that of interaction with the surrounding atoms. In order to observe the atomic state non-destructively, we use RF field addition to laser light. High resolution magnetic resonance enable us to distinguish the kind of atoms and clusters. Three-dimensional magnetic resonance imaging(MRI)informs us the distribution of atoms at low temperature.At present we can observe the magnetic resonance and two-dimensional MRI of Cs in helium gas. Image is sensitively observed by optical pumping and detection. From the delay time from pumping to detection, we can look at diffusion of polarized Cs. In future we will measure the diffusion constants over wide temperature range, and MRI of rare gas atoms at low temperature.