CALCULATION OF FREQUENCIES AND RELATIVE INTENSITIES OF NUCLEAR SPIN RESONANCE LINES IN CRYSTALS

Abstract

Previous calculations of the dependence on the strength of the external magnetic field H₀ of the energy levels and the expected frequencies of nuclear spin resonance lines of Al²⁷ nuclei in a single crystal of LiAl(SiO₃)₂ (spodumene) have been extended over a wide range of H₀ to more general orientations of the crystal with respect to H₀.In order to describe the variation with H₀ of the relative signal strength of a nuclear spin resonance line in a crystal, as observed with a crossed-coil spectrometer, a system of modified Bloch equations has been set up which describe the behavior of the magnetization vector of a two-level system when transitions are induced by an oscillating magnetic field. Solutions of these equations are used to explain the difference in the dependence on H₀ of signal strengths in crossed-coil and in single-coil spectrometers.