Correlation betweenCu+-ion instability and persistent spectral hole-burning phenomena of CuCl nanocrystals

We have studied persistent spectral hole-burning (PSHB) phenomena of CuCl nanocrystals embedded in a NaCl crystal. We found correlations between the PSHB phenomena and the photoluminescence spectral changes of excitons in CuCl nanocrystals and of ${\mathrm{Cu}}^{+}$ dimers in a NaCl crystal. The spectral changes can be triggered by photoinduced ${\mathrm{Cu}}^{+}$-ion displacements in CuCl nanocrystals and in a NaCl crystal.