Bloch equations for anisotropic paramagnetic centers with spin of 1/2

The Bloch equations are an invaluable tool in magnetic resonance for describing the dynamics of isotropic spin systems. However, when the Bloch equations are reformulated for anisotropic spin systems, much of their utility is lost because the spin evolution they describe is not physically observable. A set of Bloch-like equations are derived for these anisotropic systems in terms of the magnetic moment which is the physical property measured in magnetic resonance and other experiments. The equations describe the dynamics of the magnetic moment including relaxation and only contain parameters that are experimentally measurable. (C) 2013 Elsevier Inc. All rights reserved.