Nuclear spin-lattice relaxation in finely dispersed carbonizate powders

Abstract

Finely dispersed carbonizate powders were studied with the aim of revealing their suitability for producing hyperpolarized noble gases. In the temperature and frequency dependences obtained over a wide range of temperatures and magnetic fields for the spin-lattice relaxation times of the magnetic moments of 3He, 1H, and 13C nuclei, anomalous features caused by the suppression of the exchange between surface paramagnetic centers in a magnetic field were observed. It is shown that the interaction with magnetic moments of the 1H nuclei situated near the paramagnetic centers is the main polarization-leakage channel for the noble-gas nuclear spins. © 2004 MAIK "Nauka/Interperiodica".