Spectral hole-burning and hole-filling in CuBr nanocrystals

Abstract

Transient and persistent spectral hole-burning (SHB) and hole-filling phenomena are studied in nanometer-size CuBr crystals embedded in the borosilicate glass matrix. Pulsed dye lasers are used to measure SHB in the inhomogeneously broadened excitonic absorption bands at low temperatures. While large nanocrystals show only overall changes of absorption bands, in small nanocrystals (mean radius < 4 nm) relatively narrow spectral holes are generated by a selective excitation. SHB is studied at different photon energies and at different temperatures from 2 to 180 K. By thermal effects or under excitation at photon energies different from that of the spectral hole, burned holes can be erased. The spontaneous hole-filling (HF), thermally-induced HF and light-induced HF experiments give additional information about the persistent SHB mechanism and consequently about nanocrystal-matrix interactions.