✍ Scribed by Price, William S.
No coin nor oath required. For personal study only.
Translational diffusion is the most fundamental form of transport in chemical and biochemical systems. Pulsed-field gradient nuclear magnetic resonance provides a convenient and noninvasive means for measuring translational motion. In this method the attenuation of the echo signal from a Hahn spin-echo pulse sequence containing a magnetic field gradient pulse in each period is used to measure the displacement of the observed spins. In the present article, the physical basis of this method is considered in ( ) detail. Starting from the Bloch equations containing diffusion terms, the analytical equation linking the echo attenuation to the diffusion of the spin for the case of unrestricted isotropic diffusion is derived. When the motion of the spin occurs within a confined geometry or is anisotropic, such as in in vivo systems, the echo attenuation also yields information on the surrounding structure, but as the analytical approach becomes mathematically intractable, approximate or numerical means must be used to extract the motional information. In this work, two common approximations are considered and their limitations are examined. Measurements in anisotropic systems are also considered in some detail.
📜 SIMILAR VOLUMES
In Part 1 of this series, we considered the theoretical basis behind the pulsed-field gradient nuclear magnetic resonance method for measuring diffusion. In this article the experimental and practical aspects of conducting such experiments are considered, including technical problems involved in gra
## Abstract The diffusion coefficient (__D__) values of __tert__‐butyloxycarbonyl‐glycine, __tert__‐butyloxycarbonyl‐L‐tryptophan, __tert__‐butyloxycarbonyl‐L‐phenylalanine (Boc‐Phe), and 9‐fluorenylmethoxycarbonyl‐L‐phenylalanine in Merrifield polystyrene (MPS) gels, poly(ethylene glycol)‐grafted