Student Publications
Describing NMR chemical exchange by effective phase diffusion approach
Document Type
Article
Abstract
This paper proposes an effective phase diffusion method to analyze chemical exchange in nuclear magnetic resonance (NMR). The chemical exchange involves spin jumps around different sites where the spin angular frequencies vary, which is a random phase walk viewed from the rotating frame reference. Such a random walk in phase space can be treated by the effective phase diffusion method. Both the coupled and uncoupled normal and fractional phase diffusions are considered. Based on the phase diffusion results, the line shape of NMR exchange spectrum can be obtained. By comparing these theoretical results with the conventional theory, this phase diffusion approach works for fast exchange, ranging from slightly faster than intermediate exchange to very fast exchange. For normal diffusion models, the theoretically predicted curves agree with those predicted from traditional models in the literature, and the characteristic exchange time obtained from phase diffusion with a fixed jump time is the same as that obtained from the conventional model. However, the phase diffusion with a monoexponential time distribution gives a relatively shorter characteristic exchange time constant, which is half of that obtained from the traditional model. Additionally, the fractional diffusion obtains a significantly different line shape than that predicted based on normal diffusion.
Publication Title
Communications in Nonlinear Science and Numerical Simulation
Publication Date
10-2023
Volume
125
ISSN
1007-5704
DOI
10.1016/j.cnsns.2023.107402
Keywords
chemical exchange, Mittag-Leffler function, NMR, phase diffusion
Repository Citation
Lin, Guoxing, "Describing NMR chemical exchange by effective phase diffusion approach" (2023). Student Publications. 21.
https://commons.clarku.edu/student_publications/21