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

13C Spin–Lattice Relaxation in Natural Diamond: Zeeman Relaxation at 4.7 T and 300 K Due to Fixed Paramagnetic Nitrogen Defects

“…In this case the very short electron SLR time of ∼1 58 × 10 −8 s [26], associated with the N2 center, is more effective than the P1 T 1e mechanism (∼2 2 ms) [24] and TSP1 and TSP2. The short N2 T 1e causes C to be much larger than K and results in a calculated 13 C T 1 which is within a factor of 3 of the measured value (Table 4).…”

“…Reynhardt et al [21] studied the electron SLR behavior in type I diamonds at X-band (∼3400 G) in the temperature range 300 K ≥ T ≥ 4.2 K. P1 centers exhibit a static Jahn-Teller distortion at temperatures below ∼570 K and the main spin-lattice relaxation mechanism associated with these centers seems to be phonon-induced spin-orbit tunneling. Recently, we have studied the room temperature field dependence of P1 and P2 centers [24] and observed the electron SLR times of these centers to be field independent and of the order of 2.2 ms at 300 K. The experimental results suggest that P2 centers relax via a secondorder Raman process. Since the central P1 EPR line and the P2 hyperfine lines overlap, cross-relaxation [25] takes place between P1 and P2 centers.…”

Spin lattice relaxation of spin‐½ nuclei in solids containing diluted paramagnetic impurity centers. I. Zeeman polarization of nuclear spin system

“…It was assumed that within the cluster of P2 lines and the central P1 line crossrelaxation between the different types of defects is fast and the spin-lattice relaxation time of all paramagnetic electrons contributing to the cluster is the same as the measured electron spin-lattice relaxation time of the central line of the P1 center. The electron spin-lattice relaxation times of P1 and P2 centers are field-independent and of the order of 2.2 ms at 300 K (27). For all the samples R Ͼ ␦ and ␦ ӷ ␤ (see Table 1) and, therefore, the 13 C spin-lattice relaxation process tends toward the rapid-diffusion limiting case.…”

“…It seems that cross-relaxation between the P1 and N2 spins is not fast enough to establish a common spinlattice relaxation rate for the cluster of overlapping P1 and N2 lines in this case. The electron spin-lattice relaxation time of ϳ1.58 ϫ 10 Ϫ8 s of the N2 center (28) is much shorter than that of the P1 center (ϳ2.2 ϫ 10 Ϫ3 s) (27), suggesting that the coupling between the N2 spin reservoir and the lattice is much stronger than the coupling between the N2 and P1 reservoirs, resulting in nonexponential relaxation of the overlapping P1 and N2 lines. It seems that the short T 1 (e) value of the N2 center results in a T 1 (e) mechanism that is much more effective than the T 1 (e) mechanism of the P1 centers and homogeneous and heterogeneous three-spin mechanisms.…”

“…• ␤, the distance up to where direct polarization of 13 C spins is effective (Eq. [27]). • R, the average distance between neighboring impurity centers (Eq.…”