Nonlinear time-series analysis of photoinduced fluorescence oscillation in a water dispersion of colloidal quantum dots

We report on photoinduced fluorescence oscillation observed in a water dispersion of CdSe/ZnS core/shell quantum dots (QDs). The fluorescence intensity spontaneously oscillates under continuous excitation in a temperature-sensitive manner and emerges at 29-30 degreesC. The experimental results suggest that the fluorescence oscillation occurs only in the presence of QD aggregates. The oscillation is characterized by wavelet and nonlinear time-series analyses of the fluorescence intensity data at 30 degreesC. The results reveal self-similarity and nonlinearity, suggesting that the fluorescence oscillation is governed by nonlinear dynamics and is a special class of photoinduced chemical oscillation.