Room-temperature field dependence of the electron spin–lattice relaxation times of paramagnetic P1 and P2 centers in diamond

Electron spin–lattice relaxation (SLR) times of P1 and P2 centers have been measured at 300 K at X-band and W-band for one synthetic (type-Ib) and three natural (type-Ia) diamonds using electron paramagnetic resonance spectroscopy. Bi-exponential SLR, with a fast and a slow component, was observed for the overlapping lines of samples with two types of impurity centers. Comparison of X- and W-band results for P2 centers suggests that these centers relax via a field-independent second-order Raman process with T1e≈2.2 ms at room temperature.