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

在低温下，可以用光学方法观察到受周围粒子热运动的非相干扰动的原子态动力学。原子相干性信息有助于学习量子力学的基本概念。通过观察内部电子壳层之间的光学跃迁，研究了液氦和固体氦中的Tu原子。通过在固体氦中捕获高密度的Tu原子来检测亚稳态。这一结果使固体氦中的原子适用于原子常数的精确测量。我们还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学跃迁的能量或相位，这是精确原子钟必须研究的问题。我们将碱卤化物晶体中的O^-__视为高密度分子，并以高的时间分辨率和光谱分辨率观测到了发射。原子和分子在低温下的光学探测很容易改变其电子态和结构，因为光能远大于与周围原子相互作用的能量。为了非破坏性地观察原子态，我们在激光的作用下加入了射频场。高分辨率磁共振使我们能够区分原子和团簇的种类。三维磁共振成像(MRI)向我们提供了低温下原子的分布情况，目前我们可以观察到Cs在氦气中的磁共振和二维MRI。通过光抽运和检测，可以灵敏地观察到图像。从泵浦到探测的延迟时间，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，以及低温下稀有气体原子的磁共振成像。

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.