Nonlinear sampling in ultrafast Laplace NMR.

Vladimir V Zhivonitko,Ville-Veikko Telkki,Md Sharif Ullah

doi:10.1016/j.jmr.2019.106571

Vladimir V Zhivonitko, Ville-Veikko Telkki + Show 1 more

Open Access

https://doi.org/10.1016/j.jmr.2019.106571

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Abstract

Ultrafast Laplace NMR (UF-LNMR) reduces the experiment time of multidimensional relaxation and diffusion measurements to a fraction. Here, we demonstrate a method for nonlinear (in this case logarithmic) sampling of the indirect dimension in UF-LNMR measurements. The method is based on the use of frequency-swept pulses with the frequency nonlinearly increasing with time. This leads to an optimized detection of exponential experimental data and significantly improved resolution of LNMR parameters.

Highlights

NMR relaxation and diffusion experiments provide detailed information about molecular rotational and translational motion as well as chemical resolution complementary to frequency spectra [1,2,3]
We demonstrated a method for nonlinear sampling of indirect dimension in the UF IR and T1-T2 correlation experiments
The method is based on the use of frequency-swept pulses with the frequency nonlinearly increasing with time. This leads to more optimal detection of single-exponential data and much more optimal detection of multi-exponential data with T1 values differing significantly

Summary

Introduction

NMR relaxation and diffusion experiments provide detailed information about molecular rotational and translational motion as well as chemical resolution complementary to frequency spectra [1,2,3]. The experiments result in exponentially decaying or increasing data, and the distribution of relaxation times or diffusion coefficients is solved by the inverse Laplace transform [4]. The relaxation and diffusion experiments are called Laplace NMR. Like in traditional NMR spectroscopy, the resolution and information content of LNMR can be increased substantially by a multidimensional approach [1,2,3]. The approach leads to very long experiment times due to need for repetitions with an incremented evolution time or gradient strength. The need for repetitions significantly hinders the use of modern hyperpolarization methods [5,6,7,8], which otherwise could improve the experimental sensitivity up to five orders of magnitude

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