Measurement of electron spin flip-flop time

我们测量了红宝石中<Cr^(3+)>的基态<^4A_2>的（+1/2）亚能级上电子自旋的触发器时间。这是世界上第一个直接测量二能级电子自旋系统触发器时间的实验。在本实验中，我们使用了我们在同一电子自旋系统中提出并检验的光学标记方法。(理论物理,牧师。B30 2983,'84)在高于500 Oe的外加磁场下约为10秒（0.05 wt%）。它比A.Szabo通过间接测量得到的报告值要长。造成这种差异的原因一直没有弄清楚。我们需要对浓度和磁场依赖性进行更精确的测量。我们还研究了固体中稀自旋体系交叉弛豫时间的理论计算。我们提出了自旋触发器时间的时间依赖关系，它将成正比于<t^(-1/2)>。理论和实验研究表明，描述两能级自旋系统的布洛赫方程并不总是正确的。在饱和度和均匀线的形状展宽上，实验结果与理论预测的差异变得明显。（光学通讯，51,163,'84）造成这种差异的原因是非纯的二能级系统。由于周围顺磁核之间的超光速相互作用，它伴随着许多亚能级。我们测量了在外加磁场作用下稀红宝石<R_1>谱线-分量的均匀谱宽，用上述理论解释了结果。

We have measured the flip-flop time of electron spins in the (+1/2)sublevels of the ground state <^4A_2> of <Cr^(3+)> in ruby. (Phys.Rev.B34.1972,'86) It is the first experiment in the world to measure directly the flip-flop time of a two-level elctron spin system. In this experiment, we used the method of optical labeling, which is proposed and examined by us in the same electron spin system. (Phys,Rev. B30 2983,'84) It is about 10 sec ( 0.05 wt% ) at the applied magnetic fields, higher than 500 Oe. It is longer than the reported value by A.Szabo obtained by indirect measurment. The cause of the difference has never been understood. We need much more precise measurements of concentration and magnetic field dependence. We also investigated the theoretical calculation of cross relaxation time in dilute spin system in solids.(Phys. Rev.B29.6043,'84) We porposed the time dependence of the spin flip-flop time, which will be proportional to <t^(-1/2)> .Theoretical and experimental investigation to show that Bloch equations to describe a two-level spin system are not always correct. In the saturation and the shape of homogeneous line broadening, differences between the experimental results and the theoretical anticipations become clear. (Optics Commun.51,163,'84) The cause of the differences is attributed to non-pure two level system. which is accompanied by many sublevels due to superhyperfyne interaction between surrounding paramagnetic nuclei. We have measured homogeneous line broad-ening of -components of <R_1> line in a dilute ruby at applied magnetic fileds and results are explained by the same idea reported above.