Hyperpolarized Xe atoms and atomic magnetometer for the detection of ultralow magnetic field

本研究项目的目标是研制具有自旋极化的Xe和Rb原子的混合设置的精密原子磁强计。要利用Xe原子本身具有较长的自旋弛豫时间，就必须在不损失自旋极化的情况下长时间保持原子的高密度。我提出了将超极化Xe原子溶解在某些液体中的想法，在这种液体中，在正常情况下，密度更高的Xe原子可以实现为气相。发现了溶液中的自旋弛豫、核偶极子相互作用、与溶剂分子的自旋-旋转相互作用以及壁弛豫机制。由于前人的大量工作澄清了气相中的弛豫机制，因此在自旋弛豫过程中，壁弛豫占主导地位。如果我们克服了壁弛豫，我们将获得极高的气体原子极化。我们的高场核磁共振测量是引导我们理解壁上的自旋相互作用的希望之一。通过探测纯金属熔点附近的奈特位移，我们能够重建金属-杂质合金的相图。然后，我们指定了两种杂质可以溶解在玻璃池中的碱金属中。一个是氧原子。一旦氧原子溶解成碱金属，微量氧均匀地从金属的导带中带走电子。由于表面电子密度与~3He原子的核自旋弛豫有关，我们的发现为精确控制氧密度和在玻璃表面开发新型镀膜材料提供了技术基础。除了上面提到的壁弛豫，我们还发现了角动量可以转移到固体的新现象。通过光学泵浦气态Cs原子，发现CSH盐的Cs核在2.7T和100℃时的极化是热平衡的19倍。

The target of this research project is to develop the precise atomic magnetometer with the hybrid setup of spin-polarized Xe and Rb atoms. To utilize Xe atoms with intrinsically-long spin-relaxation time, it is necessary to preserve atoms at high density for a long time without loss of spin-polarization. I came up with the idea to solvate the hyperpolarized Xe atoms in some liquid where much higher density can be realized as gas phase at normal condition. The mechanism of spin-relaxation in solution, nuclear dipole interaction and spin-rotation interaction with solvent molecules, as well as wall relaxation was found. Wall relaxation is mostly dominant in spin-relaxation process since enormous numbers of past works cleared up the relaxation mechanism in gas-phase. We would get extremely high polarization of gaseous atoms if we overcame the wall relaxation. Our high field NMR measurement is one of hopes to lead us to understand the spin interaction at the walls. We are able to regenerate phase diagram of metal-impurities alloy by detecting Knight shift near the melting points of pure metal. Then, we assigned that two species of impurities can solve in alkali-metal in the glass cells. One is oxygen atoms. Once oxygen atoms solved into alkali-metal, the trace oxygen homogeneously takes electron from conduction band of metal. Since the electron density at surface is related to the nuclear spin relaxation of ^3He atoms, our finding gave as the technique to control precisely the oxygen density and to develop novel coating materials on the glass surface. In addition to wall relaxation mentioned above, we discovered the new phenomenon that the angular momentum can be transferred to a solid. By optically pumping gaseous Cs atoms, Cs nuclei of CsH salt was found to be polarized as 19-times as thermal equilibrium at 2.7T and 100℃.