T 1,Nuclear Overhauser Effects Measurements in 13 C NMR Spectroscopy: Analytic Relations for Short Equilibration Delays

Abstract

Analytic relations that describe magnetization as a function of time are given for several dynamic nuclear Overhauser effects (NOE) experiments. They allow the extraction of spin-lattice relaxation times (T₁) and NOE (η) from a three-parameter fitting of experimental data. These results are valid even for short equilibration delays if the saturated protons have a much shorter relaxation time than the observed ¹³C. A simple pulse sequence that combines a progressive saturation experiment with gate decoupling is proposed for measuring T₁ and η values. The calculated η values are a good approximation even for short equilibration delays without any restrictive assumptions about relaxation times of the nuclei involved.