Dynamics of Spectroscopic Relaxation Processes in Noise Fields

噪声场中光谱弛豫过程的动力学

• 批准号: 02640292
• 负责人: FUKUDA Yukio
• 金额: $ 1.6万
• 依托单位: College of Liberal Arts, Kobe University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640292/
• 关键词: Noise Field; Spectroscopy; Relaxation Process; Two-State Noise; Antiferromagnet CsCoCl_3; Gaussian-Markov Noise; Stochastic Theory; レ-ザ-分光; 磁気共鳴; 位相緩和

The aim of this research project is to reconsider the fundamental concepts of relaxation processes in the coherent spectroscopy and to establish a comprehensive procedure for describing the spectroscopic relaxation processes.We made an pulsed-NMR experiment in which NMR coherent transient phenomena (free induction decay. spin echo, etc.) of proton spins in water were examined. After making some preliminary experiments by using noise sources like a noise diode, we developed computer programs for generating variety of well-defined noises. Then the noise is applied with a coil in the direction parallel to the static magnetic field through a D/A converter and a current amplifier. The phase relaxation time T_2 was measured and analyzed.Firstly, we studied the case of two-state noise, one of the simplest and the most fundamental type of noises, and obtained a noticeable result. We considered a Markov process in which the magnetic field randomly jumps back and force between two states with di … More fferent lifetimes tau_1 and tau_2. In this case, we could obtain analytically an expression of the decay function for the coherent transients. Especially for tau_1>>tau_2, we theoretically obtained a exponential decay with a time constant T_2 (the phase relaxation time) given by1/T_2=(1/tau_1)gamma^2deltaH^2tau_2^2/(1+gamma^2deltaH^2tau_2^2) where gammaH is the difference of the magnetic field between the two states. This formula was confirmed by the experiment. The conventional stochastic theory predicts the same result only in the limit of gamma^2deltaH^2tau_2^2<<1 and it can not be not used for gamma^2deltaH^2tau_2^2-1 or >1.Secondly, we applied the above result to the phase relaxation of the Cs NMR observed in Ising-like antiferromagnet CsCoCl_3 and elucidated the dynamical process of the magnetic spin system of Co ions. This result is worth noticing in the meaning that it shows the usefulness of the measurement of the NMR phase relaxation in the study of magnetic materials.Lastly, we have been studying phase relaxation processes under Gaussian-Markov noises and already obtained some new results.A paper reporting on two-state noises has been submitted and another on CsCoCl_3 is about to be submitted. The result on Gaussian noises will also be reported before long. Less

这项研究的目的是重新考虑相干光谱中弛豫过程的基本概念，并建立描述光谱弛豫过程的全面程序。我们进行了一个脉冲核磁共振实验，在这个实验中，核磁共振相干瞬变现象(自由感应衰变)。自旋回波等)对水中质子的自旋进行了研究。在使用噪声二极管等噪声源进行了一些初步实验后，我们开发了产生各种清晰噪声的计算机程序。然后通过D/A转换器和电流放大器在平行于静磁场方向的线圈上施加噪声。首先，我们研究了最简单、最基本的噪声类型之一--双态噪声的情况，得到了一个值得注意的结果。我们考虑了一个马尔可夫过程，在这个过程中，磁场随机地跳回并在具有di…的两个状态之间作用力。在这种情况下，我们可以解析地得到相干瞬变的衰变函数的表达式。特别是对于tau_1&gt；&gt；tau_2，我们在理论上得到了随时间常数T_2(相松弛时间)的指数衰减，其中by1/T_2=(1/tau_1)gamma^2deltaH^2tau_2^2/(1+gamma^2deltaH^2tau_2^2)是两个态之间的磁场之差。这一配方得到了实验的证实。传统的随机理论只在伽马^2deltaH^2tau_2^2和lt；1的极限范围内预测相同的结果，而不能用于伽马^2deltaH^2tau_2^2-1和&gt；1。其次，我们将上述结果应用于类伊辛反铁磁体CsCoCl3中观察到的Cs-核磁共振的相弛豫，阐明了Co离子的磁自旋系统的动力学过程。这一结果值得注意的是，它表明了核磁共振相松弛测量在磁性材料研究中的有效性。最后，我们一直在研究高斯-马尔可夫噪声下的相松弛过程，并已经获得了一些新的结果。一篇关于两态噪声的论文已经提交，另一篇关于CsCoCl3的论文即将提交。关于高斯噪声的结果也将在不久的将来公布。较少

项目成果

T.Kohmoto.Y.Fukuda,M.Kunitomo et al.: "Domain-Wall Pairing in the 3D-Ordered Phase of an Ising-Like Antiferromagnet CsCoC13 Studied by NMR Transverse Relaxation" (submitted to Phys.Lett.A.). (1992)

T.Kohmoto.Y.Fukuda、M.Kunitomo 等人：“通过 NMR 横向弛豫研究了类 Ising 反铁磁体 CsCoC13 的 3D 有序相中的畴壁配对”（提交给 Phys.Lett.A.）。

T.Kohmoto, T.Goto, S.Maegawa, N.Fujiwara, Y.Fukuda, M. Kunitomo and M.Mekata: "Domain-Wall Pairing in the 3D-Ordered Phase of an Ising-Like Antiferromagnet CsCoCl_3 Studied by NMR Transverse Relaxation" (Phys. Lett. A.).

T.Kohmoto、T.Goto、S.Maegawa、N.Fujiwara、Y.Fukuda、M. Kunitomo 和 M.Mekata：“通过 NMR 横向研究伊辛类反铁磁体 CsCoCl_3 3D 有序相中的磁畴壁配对

T. Kohmoto, Y. Fukuda, M. Kunitomo, K. Ebina, M. Kaburagi, K. Ishikawa and M. Tanigawa: "Phase Relaxation in a Well-Defined Noise Field" (Phys. Rev. Lett.).

T. Kohmoto、Y. Fukuda、M. Kunitomo、K. Ebina、M. Kaburagi、K. Ishikawa 和 M. Tanikawa：“明确定义的噪声场中的相位弛豫”（Phys. Rev. Lett.）。

T.Kohmoto.Y.Fukuda,M.Kunitomo et al.: "“Phase Relaxation in a Well-Defined Noise Field"" (to be submitted to Phys.Rev.Lett.). (1992)

T.Kohmoto.Y.Fukuda、M.Kunitomo 等人：““明确定义的噪声场中的相位弛豫””（将提交给 Phys.Rev.Lett.）（1992 年）。