Dynamics of Spectroscopic Relaxation Processes in Noise Fields

本工作的目的是重新审视相干光谱学中弛豫过程的基本概念，并建立一种理解和描述光谱弛豫现象的一般方法。以自旋1/2体系的核磁共振瞬态为例，从随机涨落作为弛豫源的观点出发，研究了以下问题：1 .通过精密测量和人工合成噪声场下弛豫现象的计算机模拟，考察了噪声特性与弛豫现象之间的关系；为了阐明基于常规随机松弛理论的解析处理的局限性，并寻找一种描述广义条件下松弛现象的方法。在任意相关次数的合成噪声光下，观察光学二能级系统的相干瞬态。研究噪声光激发下的弛豫过程。本工作的成果总结如下：1。通过编写程序，合成了任意参数的两态型和高斯型噪声。2. 在与静磁场平行的噪声磁场中，对水中质子的核磁共振相干瞬态进行了精确测量，并对因相位变化而随机化的相位敏感探测信号（PSD）进行多次平均，得到了与横向弛豫相对应的衰减曲线。3. 通过改变噪声场的幅值和相关时间，精确测量了在非均匀磁场下烧蚀孔的形状和宽度，并与布洛赫方程的预测结果进行了比较。4. 在Rb蒸气中进行了噪声激发光谱分析，通过输入噪声光与输出光强度相关的傅里叶变换得到了噪声激发光谱。

The aim of this work is to re-examine the fundamental concept of relaxation processes in the coherent spectroscopy and to establish a general method for understanding and describing the spectroscopic relaxation phenomena. Taking NMR transients in the spin 1/2 system, we study the following subjects from the view point of regarding random fluctuations as the origin of the relaxation : I.To examine relation between the characterstics of noises and relaxation phenomena studied by pecise measurements and computer simulation of relaxation phenomena under artificially synthesized noise fields, 2. To clarify the limit of the analytical treatments based on the conventional stochastic theory of relaxation, and to search a method describe relaxation phenomena under generalized conditions, 3. To observe coherent trnsients in a optical two-level system under synthesized noise-lights with arbitrary corelation times, and 4. To investigate the relaxation processes under noise-light excitation.The summary of the results of this work is as follows 1. Two-state type and Gaussian type noises with arbitorary parameters were synthsized by developing a computer program. 2. NMR coherent transients of the protons in water were precisely measured in a noise magnetic field applied parallel to the static magnetic field, where the phase-sensitively-detected (PSD) signals randomized due to the shot-by-shot change of the signal phases were averaged many times to give decay curves corresponding to the transverse relelaxation. 3. The shapes and widths of the holes burnt under an inhomogeneous magnetic field was precisely measured with varying the amplitude and correlation time of the noise field and the results were compared with the prediction of the Bloch equations. 4. A noise excitation spectroscopy was performed in Rb vapor, where the spectra were obtained from the Fourier transform of the intensity correlation between the input noise-light and the output light.