Nonlinear Time-Series Analysis of Photoinduced Fluorescence Oscillation in a Water Dispersion of Colloidal Quantum Dots

Abstract

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 °C. 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 °C. 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.

Enhancement of the photoluminescence of CdSe quantum dots during long-term UV-irradiation: privilege or fault in life science research?

“…A photoinduced enhancement of PL-intensity has already been described for CdSe close-packed nanocrystal films, monolayers and organic solutions during broad-band VIS-illumination [15][16][17]. On our knowledge, this is a first report demonstrating an enhancement of PL-intensity of water-soluble CdSe nanocrystals during long-term UV-irradiation at physiological conditions.…”

Photoenhancement of lifetimes in CdSe/ZnS and CdTe quantum dot-dopamine conjugates

“…Previous studies have observed fluorescence oscillations in QD solutions, which were dependent upon salt concentration and temperature and had a period of B8 min. 32 These were attributed to interaction with ions in the solution. Our oscillations occurred on a faster time scale, but are consistent with the same explanation.…”

Perturbation of the tris(2,2′‐bipyridine) ruthenium(II)‐catalyzed Belousov–Zhabotinsky oscillating chemiluminescence reaction by l‐cysteine and its application

“…, which was reduced to Ru(bpy) 3 2+ directly without light emission. Such a course inhibited the reaction of BrC • (COOH) 2 and Ru(bpy) 3 3+ from Process C. Consequently, the concentration of the Ru(bpy) 3 2+* was decreased and the generating rate of Br − was depressed, which resulted in a decrease in…”

“…Since there are some obvious similarities between chemical oscillating systems and life processes that generally exhibit oscillatory behaviors, the investigation of the oscillating systems is of considerable interest. While a substantial number of chemical oscillators are known and have been widely used in analytical detection, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] relatively few oscillating chemiluminescence (CL) reactions in the liquid phase have been described. [15][16][17][18][19][20] Recently, owing to the particular photochemical and photophysical properties of the tris(2,2′-bipyridine)ruthenium(II) [Ru(bpy) 3 2+ ] CL reagent, [21][22][23] the Ru(bpy) 3…”