Although there exist a variety of NMR sequences for measuring diffusion, they all share a common theme of refocussing magnetisation while using gradient pulses to apply a spatially-dependent phase to the signals. Figure 1 shows the basic scheme for diffusion measurement using the PFG (Pulsed Field Gradient) spin-echo. Figure 1. The PFG spin ...
Diffusion measurements in NMR refer to translational diffusion, not rotational diffusion nor to “spin diffusion”. For random, Brownian motion, of a spherical molecule, the Stokes-Einstein relation is: where η is viscosity, T is temperature, r is the hydrodynamic radius, and D is the diffusivity.
液体核磁共振之动力学分析方法（A）：扩散排序谱 Dynamics Analysis by Solution NMR …
2020年4月29日 · 扩散核磁共振可用于解析混合物的复杂谱图，也可用于确定分子和聚集体的大小，确定聚合度、溶剂化壳的尺寸或其他微观结构。 生成的核磁谱图在某些方面类似于色谱图，同时也提供了高分辨的核磁共振信息，可用于单个组分的结构归属（Figure 1）。 然而，对于大多数混合物，其分辨率不足以进行直接归属，需要应用核磁共振色谱技术。 Figure 1. A …
Diffusion NMR
The diffusion NMR technique is often referred to as Self-Diffusion (SD)-NMR or Diffusion Ordered SpectroscopY (DOSY). This is achieved by combining radio-frequency pulses as used in routine NMR spectroscopy with magnetic field gradients that encode spatial information.
Diffusion-Ordered NMR Spectroscopy | Manchester NMR …
Diffusion-ordered spectroscopy (DOSY) seeks to separate the NMR signals of different species according to their diffusion coefficient. A series of spin echo spectra is measured with different pulsed field gradient strengths, and the signal decays are analysed to extract a set of diffusion coefficients with which to synthesise the diffusion ...
In this course we will focus directly on how to measure diffusion by NMR, how to process the data and some of its applications: Relative diffusion information -> separation/identification of NMR spectra from different components in a mixture. Diffusion-ordered spectroscopy (DOSY) Absolute diffusion information -> size estimation of molecules ...
Diffusion NMR spectroscopy - ScienceDirect
2009年1月1日 · Diffusion measurements have become routinely accessible with conventional high-resolution NMR spectrometers through the introduction of actively shielded pulsed field gradient probe heads.
Diffusion ordered nuclear magnetic resonance spectroscopy: …
1999年5月20日 · This groundbreaking experiment, carried out on a standard commercial NMR spectrometer, established the basic NMR diffusion measurement still in use. The authors recognized the analytical implications, because each component of a mixture is revealed by its unique diffusion coefficient, and possibilities for the study of dynamics in solutions.
Pulsed Field Gradient Nuclear Magnetic Resonance and Diffusion …
2021年11月11日 · Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) is a widely used method for determining the diffusion coefficient of ions and molecules both in the bulk and when confined (e.g., within porous materials).
Diffusion NMR studies of complex liquid formulations
2020年8月1日 · dNMR allows the determination of the components distribution in complicated systems. From diffusivity a volume-averaged size of the components is evaluated. This is an introductory review on the diffusion Nuclear Magnetic Resonance (dNMR) as a powerful tool to characterise different types of formulations.