Automatic spin-Hamiltonian diagonalization for electronic doublet coupled to anisotropic nuclear spins applied in one- and two-dimensional electron spin-echo simulations

Abstract

We explore the possibility of putting together some earlier theoretical inventions in electron paramagnetic resonance (EPR) into an efficient method leading to accurate explicit expressions of echo modulation spectra in one and two dimensions. The resulting “automatic” diagonalization of the high-field spin-Hamiltonian gives a quick method for Electron spin-echo modulation computations. It accounts accurately for the effects of nonaxial electron Zeeman and hyperfine coupling tensors to an arbitrary system of nuclei in any relative orientations, including also the secular part of the quadrupole tensors in the computation of the modulation frequencies. Explicit expressions for the time-resolved signals, involving a single geometric parameter, particularly useful in economizing powder simulations of multipulse sequences like hyperfine sublevel correlation spectroscopy (HYSCORE), are presented. Finally, implementation in a complete package including fundamental EPR-line shape, primary-echo, stimulated-echo, and HYSCORE simulations and application to computations in experimentally interesting model systems is demonstrated. ©2000 John Wiley & Sons, Inc. Concepts Magn Reson 12: 410–433, 2000