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Luminescence of colloidal CdSe/ZnS nanoparticles: high sensitivity to solvent phase transitions.

Antipov A, Bell M, Yasar M, Mitin V, Scharmach W, Swihart M, Verevkin A, Sergeev A - Nanoscale Res Lett (2011)

Bottom Line: We investigate nanosecond photoluminescence processes in colloidal core/shell CdSe/ZnS nanoparticles dissolved in water and found strong sensitivity of luminescence to the solvent state.First of all, the luminescence intensity substantially (approximately 50%) increases near the transition.The observed effects are associated with the reconstruction of ligands near the ice/water phase transition.

View Article: PubMed Central - HTML - PubMed

Affiliation: Electrical Engineering Department, University at Buffalo, Buffalo, NY 14260, USA. vmitin@buffalo.edu.

ABSTRACT
We investigate nanosecond photoluminescence processes in colloidal core/shell CdSe/ZnS nanoparticles dissolved in water and found strong sensitivity of luminescence to the solvent state. Several pronounced changes have been observed in the narrow temperature interval near the water melting point. First of all, the luminescence intensity substantially (approximately 50%) increases near the transition. In a large temperature scale, the energy peak of the photoluminescence decreases with temperature due to temperature dependence of the energy gap. Near the melting point, the peak shows N-type dependence with the maximal changes of approximately 30 meV. The line width increases with temperature and also shows N-type dependence near the melting point. The observed effects are associated with the reconstruction of ligands near the ice/water phase transition.

No MeSH data available.


Related in: MedlinePlus

PL intensity. of dry (a) and in-liquid colloidal (b) CdSe/ZnS NPs as functions of temperature and wavelength.)(color online).
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Figure 1: PL intensity. of dry (a) and in-liquid colloidal (b) CdSe/ZnS NPs as functions of temperature and wavelength.)(color online).

Mentions: The PL intensity of dry CdSe colloidal NPs as a function of temperature and wavelength is shown in Figure 1a. The integrated emission intensity (integration is done within λ = 550-650 nm range) slightly decreases as the temperature increases from 10 K up to 70 K. Then, at higher temperatures, it quenches dramatically in the temperature range of T = 70-300 K and exhibits exponential behavior. We did not observe any significant changes in PL over that temperature range, except very slow oscillation in PL tail. It is important to notice that the saturation of PL intensity observed in our experiment at the temperatures below 50 K is certainly related to the pulse repetition rate of the laser (12.5 ns) because the low-temperature radiative lifetime of the exciton can achieve an unusually long recombination time of 1 μs at very low temperatures below 10 K and the stronger dependence of PL intensity can be expected in experiments with low repetition rate excitation [7].


Luminescence of colloidal CdSe/ZnS nanoparticles: high sensitivity to solvent phase transitions.

Antipov A, Bell M, Yasar M, Mitin V, Scharmach W, Swihart M, Verevkin A, Sergeev A - Nanoscale Res Lett (2011)

PL intensity. of dry (a) and in-liquid colloidal (b) CdSe/ZnS NPs as functions of temperature and wavelength.)(color online).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211190&req=5

Figure 1: PL intensity. of dry (a) and in-liquid colloidal (b) CdSe/ZnS NPs as functions of temperature and wavelength.)(color online).
Mentions: The PL intensity of dry CdSe colloidal NPs as a function of temperature and wavelength is shown in Figure 1a. The integrated emission intensity (integration is done within λ = 550-650 nm range) slightly decreases as the temperature increases from 10 K up to 70 K. Then, at higher temperatures, it quenches dramatically in the temperature range of T = 70-300 K and exhibits exponential behavior. We did not observe any significant changes in PL over that temperature range, except very slow oscillation in PL tail. It is important to notice that the saturation of PL intensity observed in our experiment at the temperatures below 50 K is certainly related to the pulse repetition rate of the laser (12.5 ns) because the low-temperature radiative lifetime of the exciton can achieve an unusually long recombination time of 1 μs at very low temperatures below 10 K and the stronger dependence of PL intensity can be expected in experiments with low repetition rate excitation [7].

Bottom Line: We investigate nanosecond photoluminescence processes in colloidal core/shell CdSe/ZnS nanoparticles dissolved in water and found strong sensitivity of luminescence to the solvent state.First of all, the luminescence intensity substantially (approximately 50%) increases near the transition.The observed effects are associated with the reconstruction of ligands near the ice/water phase transition.

View Article: PubMed Central - HTML - PubMed

Affiliation: Electrical Engineering Department, University at Buffalo, Buffalo, NY 14260, USA. vmitin@buffalo.edu.

ABSTRACT
We investigate nanosecond photoluminescence processes in colloidal core/shell CdSe/ZnS nanoparticles dissolved in water and found strong sensitivity of luminescence to the solvent state. Several pronounced changes have been observed in the narrow temperature interval near the water melting point. First of all, the luminescence intensity substantially (approximately 50%) increases near the transition. In a large temperature scale, the energy peak of the photoluminescence decreases with temperature due to temperature dependence of the energy gap. Near the melting point, the peak shows N-type dependence with the maximal changes of approximately 30 meV. The line width increases with temperature and also shows N-type dependence near the melting point. The observed effects are associated with the reconstruction of ligands near the ice/water phase transition.

No MeSH data available.


Related in: MedlinePlus