On Room-Temperature Inversion of EPR Signals of P1 Centre in Synthetic Diamond

Room-temperature inversion of EPR absorption signals of P1 centre in synthetic diamond is studied by the transient nutation technique. Use of the bichromatic field, consisting of a transverse microwave field and longitudinal radio frequency field, allows to investigate the dynamics of P1 centres in the same field configuration as in cw EPR spectrometers. It is shown that the annealing decreases the P1 centre concentration and, respectively, increases the spin-spin relaxation time. As a result, the periodic inversion (nutation) of the P1 centre absorption signal is observed longer. It is assumed that the P1 centre signal inversion, which was previously observed by cw EPR, might be caused by the Bloch-Siegert effect in the bichromatic field.