Dead time-dependent line distortions in absolute-value electron spin echo envelope modulation spectra

It is shown that in pulse EPR experiments, absolute-value spectra can be di storted because of the instrumental dead time to an extent that the interpr etation of the spectral features becomes impossible. The mathematical backg round for the description of the distortions is given, and the far-reaching consequences of the effect are illustrated by model calculations. A cross- term averaging procedure is proposed to get rid of these distortions in two -, three-, and four-pulse electron spin echo envelope modulation experiment s. The potential of cross-term averaging is demonstrated in two- and three- pulse experiments on a single crystal and a powder sample. (C) 1999 Academi c Press.