Right-angle wiggling electron paramagnetic resonance spectroscopy

Right-angle wiggling (RAW) electron paramagnetic resonance (EPR) spectrosco py is introduced. In this two-dimensional pulse EPR technique the orientati on of the external magnetic field B-0 is varied during the pulse sequence. For this purpose an additional sinusoidal field of variable amplitude Delta B(0)(perpendicular to) is applied perpendicular to the orientation of B-0. RAW-EPR is an alternative and experimentally much less demanding technique to right-angle spinning for performing anisotropy-resolved EPR experiments [Sierra and Schweiger, Mol. Phys. 95, 973 (1998)]. It can be applied to imp rove the resolution of EPR spectra of orientationally disordered systems or to separate overlapping single-crystal EPR spectra, and to facilitate an u nambiguous interpretation of these spectra. A detailed theoretical descript ion of RAW-EPR is given. Model calculations for systems with axial and orth orhombic symmetry, as well as a number of RAW-EPR experiments on paramagnet ic systems with anisotropic interactions are presented. (C) 2001 American I nstitute of Physics.