TEMPERATURE-DEPENDENCE OF SPIN-SPIN AND SPIN-LATTICE RELAXATION-TIMESOF PARAMAGNETIC NITROGEN DEFECTS IN DIAMOND

Spin-lattice relaxation times of P1 centers in a suite of two natural type Ib, two synthetic type Ib, and one natural type Ia diamonds were measured at 9.6 GHz as a function of temperature in the range 300 K> T > 4.2 K. An analysis of the results revealed that for three of the dia monds (two synthetic type Ib and the natural type Ia) spin-orbit phono n-induced tunneling is the main relaxation mechanism. In the case of t he Ia diamond cross-relaxation takes place between P1 and P2 centers. In the natural type Ib samples a much more effective relaxation mechan ism dominates at lower temperatures. Electron spin resonance spectra o f the latter samples revealed the presence of N3 centers. It seems tha t the more effective relaxation mechanism is associated with the N3 ce nters and that the P1 centers relax via the N3 centers to the lattice at these temperatures. (C) 1998 American Institute of Physics. [S0021- 9606(98)00343-2].