Determination of the size-distribution of CuBr nanocrystals in a glassy matrix by means of high-temperature UV–visible absorption spectroscopy

Abstract The size-distribution of CuBr nanocrystals embedded in a glassy matrix was investigated using high-temperature UV–visible absorption spectroscopy. The investigations were carried out with a photodiode array spectrometer in the temperature range from 25°C to 350°C. The absorbance of the excitonic z1/2 and z3 peaks of the CuBr nanocrystals decreases with increasing temperature. This effect is due to a size-dependent melting of the nanocrystals. We developed an analytical method, to calculate the size-distribution of the nanocrystals from the shape of the excitonic absorbance–temperature curve. The growth of a second crystal generation is observable at longer heat treatment times. Small-angle X-ray scattering (SAXS) investigations support these results. We find three crystal generations (one larger than the detection limit of our spectroscopical method). Gaussian functions are used to fit the size-distribution curves of each of these crystal generations. The sum of the distributions exhibits an increasing asymmetry during the ripening process.