Direct comparison of spin-lattice and spin-spin relaxation in high-resolution NMR

A method is presented for the simultaneous measurement of the spin-lattice (T1) and spin-spin (T2) relaxation times in 13C NMR spectroscopy by means of a simple pulse sequence used in conjunction with 2-dimensional Fourier transformation; the resulting spectra give a direct visual indication of the cases of particular interest where T2 < T1. The primary advantage of this method lies in the simultaneous measurement of both T1 and T2 under nearly identical instrumental conditions, e.g., field inhomogeneity and sample temp. The 2-dimensional display provides a convenient visual comparison of the 2 linewidths. In an application of the method, T1 and T2 of 13C were studied in 2 samples of 1,3-butanediol contg. approx. 10-5 and 10-4M MnSO4. The T2 linewidths are within 10% of the T1 linewidths except that in the sample contg. 10-4M Mn2+ the T2 lines of the 2 OH-bearing C atoms have disappeared from the spectrum because of strong preferential broadening. [on SciFinder (R)]