期刊
ACS NANO
卷 8, 期 3, 页码 2387-2398出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn405920k
关键词
quantum dots; ion trap; single particle; blinking; mass spectrometry
类别
资金
- Chemistry Division of the U.S. National Science Foundation [CHE-1111935]
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1111935] Funding Source: National Science Foundation
We report measurements of fluorescence intermittency (blinking) and spectral behavior for single semiconductor nanocrystal quantum dots (QDs) isolated in the gas phase and discuss the effects on fluorescence of the QD charge state and heating to the point of sublimation. Core shell CdSe/ZnS QDs were trapped in a quadrupole ion trap and detected by laser-induced fluorescence. The mass (M) and charge (Q) were determined nondestructively, and both were followed continuously over the course of hours or days. Emission spectra of the trapped QDs are significantly red-shifted relative to the solution-phase emission from the same particles. The temperature of the trapped QDs is determined by the balance between laser heating and collisional cooling and thermal emission, and it is possible to heat the particles to remove ligands or to the point of sublimation. QDs are observed to be emissive during sublimation, for up to 85% mass loss, with emission intensity roughly proportional to the surface area. Eventually, the fluorescence quantum yield drops suddenly, and the QDs begin to blink. The method used is versatile and will allow studies of quantum dot optical properties as a function of size, ligand removal, heating, surface oxidation, and other manipulations, where these properties are continuously correlated with the mass and charge.
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