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Updated: Jan 21, 2026

Correlative Light- and Electron Microscopy Using Quantum Dot Nanoparticles
Published on: August 7, 2016
Long-Lived Negative Photocharging in Colloidal CdSe Quantum Dots Revealed by Coherent Electron Spin Precession
Rongrong Hu1, Zhen Wu1, Yuanyuan Zhang1
1State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
Abstract:
Photoinduced charging in CdSe colloidal quantum dots (QDs) is investigated by time-resolved pump-probe spectroscopy that is sensitive to electron spin polarization. This technique monitors the coherent spin dynamics of optically oriented electrons precessing around an external magnetic field. By addition of 1-octanethiol to the CdSe QD solution in toluene, an extremely long-lived negative photocharging is detected that lives up to 1 month in an N2 atmosphere and hours in an air atmosphere at room temperature. 1-Octanethiol not only acts as a hole acceptor but also results in a reduction of the oxygen-induced photo-oxidation in CdSe QDs, allowing air-stable negative photocharging. Two types of negative photocharging states with different spin precession frequencies and very different lifetimes are identified. These findings have important implications for understanding the photophysical processes in colloidal nanostructures.
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