Analytical description of selective excitation in pulsed EPR and application to the two-pulse coherent Raman beat experiment

An analytical expression describing the evolution of an electron-nuclear spin system with anisotropic hyperfine coupling during selective microwave excitation is derived. The approach is applied to the two-pulse coherent Raman beat (CRB) EPR experiment, and is shown to be valid far beyond the linear regime approximation. The accuracy of the analytical formula is verified by model calculations, and the delay of the CRB signal observed in the linear regime is demonstrated to be a general characteristic of two-pulse CRB experiments independent of the strength of the probe pulse.