NUCLEAR RELAXATION AND DYNAMIC ORIENTATION IN HYDRATED CRYSTALS AT LOW TEMPERATURES

摘要

This paper is concerned with a detailed study of thermal relaxation and dynamic orientation of protons in single crystals of La2Mg3 (NO3)12. 24H20 in which a snail fraction of La3+ is replaced by paramagnetic Ce3+. An apparatus is described for simultaneously observing nuclear magnetic resonance (16 Mc/s) and paramagnetic resonance (9400 Mc/s) at liquid helium temperatures.nThe proton relaxation tine, T1n, is obtained from the observed exponential decay of the nuclear resonance signals at temperatures in the range 1.6 K < T < k.2 K and Ce3+ concentrations in the range 0.05 to 5%. For a fixed Ce3+ concentration, T1n-1 ∝ T7. At a fixed temperature T1n-1 is roughly proportional to the square of the Ce3+ concentration.