由于与极化$^3$ He和精确$^3$ He极化测量的自旋交换碰撞引起的$^{39}$ K的EPR谱的频移
Frequency shifts in the EPR spectrum of $^{39}$K due to spin-exchange collisions with polarized $^3$He and precise $^3$He polarimetry
摘要：
碱金属原子的塞曼分裂和EPR频率在极化惰性气体的存在下移动。对于球形几何形状，位移增强了经典的无量纲原子参数$κ_0$，这是唯一的每个碱金属原子-贵气对的预期。本文报道了对$^{39}$ K- $^3$ He系统的$κ_0$的精确测量，其相对精度优于1%.实现亚百分比精度的一个关键组成部分涉及使用MRI和CT医学成像技术来表征我们样本的形状。参数$κ_0$在各种情况下建立$^3$ He的绝对极化方面发挥着重要作用，包括电子散射实验的极化目标和肺部气体空间的MRI。当使用$κ_0$进行旋光测量时，我们的测量精度可提高一倍以上。同样重要的是，这里提出的工作代表了$^{39}$ K-$^3$ He系统的$κ_0$的第一次{ \it直接}测量; $^{39}$ K-$^3$ He系统中的$κ_0$的先前值依赖于测量链，该测量链由Rb- $^3$系统中的$κ_0$的先前测量基准化.
英文摘要：
The Zeeman splittings and EPR frequencies of alkali-metal atoms are shifted in the presence of a polarized noble gas. For a spherical geometry, the shift is enhanced over what is expected classically by a dimensionless atomic parameter $κ_0$ that is unique to each alkali-metal atom - noble-gas pair. We present a precise measurement of $κ_0$ for the $^{39}$K-$^3$He system with a relative accuracy of better than 1\%. A critical component of achieving sub-percent accuracy involved characterizing the shape of our samples using both MRI and CT medical-imaging techniques. The parameter $κ_0$ plays an important role in establishing the absolute polarization of $^3$He in a variety of contexts, including polarized targets for electron scattering experiments and MRI of the gas space of the lungs. Our measurement more than doubles the accuracy possible when using $κ_0$ for polarimetry purposes. Just as important, the work presented here represents the first {\it direct} measurement of $κ_0$ for the $^{39}$K-$^3$He system; previous values for $κ_0$ in the $^{39}$K-$^3$He system relied on a chain of measurements that were benchmarked by previous measurements of $κ_0$ in the Rb-$^3$He system.
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