A line shape analysis of free‐exciton low‐temperature (4.2 K) photoluminescence spectra is applied to monitor the heating of Si samples due to an exciting Ar⁺‐ion laser beam. The heating is studied in dependence on the laser beam intensity. The temperature as a line shape fitting parameter can be established within ±0.15 K. Continuous minor increase of the sample temperature is observed up to an intensity of ∼200 W cm⁻², followed by an abrupt temperature jump up to tens of K. Possible inaccuracies, resulting from the heating, in photoluminescent quantitative determination of boron, phosphorus, and aluminum are discussed.

Persistent spectral holes (p-SHs) are induced in the $Z_{\text{1,2}}$ excitonic absorption band of CuBr nanocrystals (NCs) in glass by selective excitation with nanosecond dye-laser pulses at low temperatures. The effect can be observed only in samples containing NCs with mean radius smaller than about 5 nm. The kinetics of p-SHs growth and the long-time relaxation (spontaneous hole-filling) after burning are studied. The burning process may be described as the first order dispersive reaction, which proceeds through a phonon-assisted tunneling between different excited states of the NC/matrix system. The same model apply in the backward reaction (hole-filling) but the tunneling takes place between different ground states of the NC/matrix system and the reaction rate is much lower. The photoproduct of persistent spectral hole-burning reaction is a charged NC which energy states are modified by the Stark effect. The quantum efficiency of burning reaction is quite high ${\text{4×10}}^{\text{−3}}$ (mean rate constant is ${\text{4×10}}^7$ ${\mathrm{s}}^{\text{−1}})$ while the rate of spontaneous HF reaction is very low (0.5 ${\mathrm{s}}^{\text{−1}}\mathrm{).}$