Electron paramagnetic resonance (EPR or ESR) is an important branch of
magnetic resonance which is usually carried out by sweeping the magne
tic field at a microwave frequency of about 9 GHz. The ESR spectrum is
described by a function of two variables, viz. magnetic field and fre
quency and the implications of field sweeping are discussed. Increasin
gly, pulsed methods, especially electron spin echo envelope modulation
and its variants, are becoming more important in all areas of ESR app
lications. Copyright (C) 1996 Elsevier Science Ltd