Lasic Samo, Stepisnik Janez, Mohoric Ales
University of Ljubljana, Faculty of Mathematics and Physics, Physics Department, Jadranska 19, 1000 Ljubljana, Slovenia.
J Magn Reson. 2006 Oct;182(2):208-14. doi: 10.1016/j.jmr.2006.06.030. Epub 2006 Jul 21.
The modulation of spin phase produced by Carr-Purcell-Meiboom-Gill (CPMG) sequence in combination with constant magnetic field gradient is appropriate to probe the displacement power spectrum (DPS). The spin-echo attenuation is directly proportional to the DPS value at the applied modulation frequency. Relaxation and selective excitation effects can be factored out while probing the DPS. The modulation frequency is adjusted by varying the pulse separation time while the gradient strength and the time of acquisition are kept constant. In designing the experiment gradient strength limitations, imposed by off-resonance effects, as well as limitations arising from using Gaussian phase approximation must be considered. An effective experimental strategy is presented, supported by experimental results for free and restricted diffusion.
由 Carr-Purcell-Meiboom-Gill（CPMG）序列与恒定磁场梯度相结合产生的自旋相位调制适合用于探测位移功率谱（DPS）。在施加的调制频率下，自旋回波衰减与DPS值成正比。在探测DPS时，可以排除弛豫和选择性激发效应。通过改变脉冲间隔时间来调整调制频率，同时保持梯度强度和采集时间不变。在设计实验时，必须考虑由失谐效应施加的梯度强度限制以及使用高斯相位近似产生的限制。本文提出了一种有效的实验策略，并给出了自由扩散和受限扩散的实验结果作为支持。
