Relationship of the inhomogeneous broadenings in the triplet state optical and ODMR spectra of NaNO2/Ag+

Abstract

The triplet state optical and ODMR spectra associated with a perturbed NO−2 anion in crystals of NaNO2 doped with AgNO2 are shown to be inhomogeneously broadened at T ≲ 4.2 K. The energies of the trap triplet state D ± E ODMR transitions depend linearly on the optical detector energy monitoring at ≲ 1 cm−1 optical resolution across a phosphorescence vibronic line whose width is ≲ 5 cm−1. The observed dimensionless slopes are ≈10−4. The corresponding ODMR linewidths are a minimum detecting at the center of the optical line and increase several-fold detecting in the wings of the optical line. A simplified model is presented, based on perturbations by random local electric fields, which accounts for the major observations. The coupling coefficients to the electric field (dipole moment changes) were independently determined from the optical and ODMR Stark shifts in an external electric field, and these appear consistent with the observed slopes for the variation of the ODMR energies with optical detector energy. The origin of the non-zero coupling coefficients for the ODMR transitions is discussed in terms of the spin—orbit interactions in the trap.