Theory of spin-exchange optical pumping of 3He and 129Xe
Theory of spin-exchange optical pumping of 3He and 129Xe
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DOI：
10.1103/physreva.58.1412
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发表时间：
1998-08-01
影响因子：
2.9
通讯作者：
Happer, W
中科院分区：
文献类型：
--
作者：
Appelt, S;Baranga, AB;Happer, W
我们通过与光泵碱金属蒸气的自旋交换碰撞提出了He-3和Xe-129气体核自旋极化的全面理论。其中最重要的物理过程是：（1）碱金属原子之间的自旋守恒自旋交换碰撞，（2）碱金属原子之间以及碱金属原子与缓冲气体原子之间的自旋破坏碰撞，（3）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（4）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（5）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（6）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（7）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（8）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（9）碱金属原子与He-3或He-129原子之间的电子-核自旋交换碰撞，（10）碱金属原子与He-3原子之间的电子-核自旋交换碰撞，（10）（4）碱金属原子与双原子组成的货车范德华分子中的自旋相互作用;（5）激光光子的光泵浦;（6）空间扩散。假设静磁场足够小，碱金属原子的核自旋与电子自旋耦合良好，总自旋非常接近一个好的量子数。假设了适合于产生大量自旋极化He-3或He-129气体的条件，即气压大气压和通过与N-2或H-2气体碰撞而使光学激发的碱金属原子几乎完全猝灭。本工作的一些重要结果如下：（1）大多数泵浦和弛豫过程相对于核极化是突然的。因此，碱金属原子的稳态布居分布很好地描述了自旋温度，无论碱金属原子之间的自旋交换碰撞的速率是大还是小相比，光泵浦速率或碰撞自旋弛豫速率。(2)除了在非常快速的自旋交换的极限之外，表征对泵浦光强度的突然变化的响应的粒子数分布不由自旋温度来描述。(3)给出的射频（rf）共振线宽和面积的表达式可以用来对碱金属原子的局域自旋极化进行可靠的估计。(4)这些高压条件下的扩散效应主要局限于细胞表面的薄层和当静磁场具有实质性的空间不均匀性时由射频磁场产生的内部共振表面。在这些表面上的扩散的高度本地化的影响描述与封闭形式的解析函数，而不是空间本征模展开，是适合于较低的压力细胞。[S1050 - 2947（98）07408 - 3]。
We present a comprehensive theory of nuclear spin polarization of He-3 and Xe-129 gases by spin-exchange collisions with optically pumped alkali-metal vapors. The most important physical processes considered an (1) spin-conserving spin-exchange collisions between like or unlike alkali-metal atoms; (2) spin-destroying collisions of the alkali-metal atoms with each other and with buffer-gas atoms; (3) electron-nuclear spin-exchange collisions between alkali-metal atoms and He-3 or Xe-129 atoms; (4) spin interactions in van der Waals molecules consisting of a Xe atom bound to an alkali-metal atom; (5) optical pumping by laser photons; (6) spatial diffusion. The static magnetic field is assumed to be small enough that the nuclear spin of the alkali-metal atom is well coupled to the electron spin and the total spin is very nearly a good quantum number. Conditions appropriate for the production of large quantities of spin-polarized He-3 or Xe-129 gas are assumed, namely, atmospheres of gas pressure and nearly complete quenching of the optically excited alkali-metal atoms by collisions with N-2 or H-2 gas. Some of the more important results of this work are as follows: (1) Most of the pumping and relaxation processes are sudden with respect to the nuclear polarization. Consequently, the steady-state population distribution of alkali-metal atoms is well described by a spin temperature, whether the rate of spin-exchange collisions between alkali-metal atoms is large or small compared to the optical pumping rate or the collisional spin-relaxation rates. (2) The population distributions that characterize the response to sudden changes in the intensity of the pumping light are not described by a spin temperature, except in the limit of very rapid spin exchange. (3) Expressions given for the radio-frequency (rf) resonance linewidths and areas can be used to make reliable estimates of the local spin polarization of the alkali-metal atoms. (4) Diffusion effects for these high-pressure conditions are mainly limited to thin layers at the cell surface and at internal resonant surfaces generated by radio-frequency magnetic fields when the static magnetic field has substantial spatial inhomogeneities. The highly localized effects of diffusion at these surfaces are described with closed-form analytic functions instead of the spatial eigenmode expansions that are appropriate for lower-pressure cells. [S1050-2947(98)07408-3].