Song Yi-Qiao
Schlumberger-Doll Research, 36 Old Quarry Road, Ridgefield, CT 06877, USA.
Magn Reson Imaging. 2003 Apr-May;21(3-4):207-11. doi: 10.1016/s0730-725x(03)00126-7.
Diffusion in porous media has been used as a probe of pore geometry in various NMR techniques. We will examine the effect of time-dependent diffusion in CPMG by showing that the diffusion time in CPMG is approximately the echo time, even in grossly inhomogeneous magnetic fields. Extension of the diffusion time in modified CPMG sequences is discussed. Diffusion in the susceptibility-contrast induced internal field is discussed as a means to probe pore size and pore shape. Finally, we present the general concept of two-dimensional relaxation-type experiments for study of molecules, fluids, materials and their dynamics that are characterized by spin relaxation and diffusion.
在各种核磁共振技术中，多孔介质中的扩散已被用作探测孔隙几何结构的手段。我们将通过表明在CPMG中扩散时间近似为回波时间来研究时间相关扩散的影响，即使在非常不均匀的磁场中也是如此。讨论了在改进的CPMG序列中扩散时间的延长。讨论了在磁化率对比度诱导的内场中的扩散，作为探测孔径和孔隙形状的一种手段。最后，我们提出了二维弛豫型实验的一般概念，用于研究以自旋弛豫和扩散为特征的分子、流体、材料及其动力学。
