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Investigation of ultrafast dynamics of CdTe quantum dots by femtosecond fluorescence up-conversion spectroscopy |
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| Authors: | Yao Guan-Xin L Liang-Hong Gui Mei-Fang Zhang Xian-Yi Zheng Xian-Feng Ji Xue-Han Zhang Hong and Cui Zhi-Feng |
| Institution: | a Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;b Institute of Atomic and Molecular Physics, Anhui Normal University, Wuhu 241000, China;c College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, China;d Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1090 GD Amsterdam, The Netherlands |
| Abstract: | The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence up-conversion spectroscopy. Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm, depending on the state of the photo-excited hole. The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots. In addition, Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps. A schematic model of photodynamics is established based on the results of the spectroscopy studies. Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem. |
| Keywords: | CdTe quantum dots femtosecond fluorescence up-conversion spectroscopy ultrafast dynamics nanomaterial |
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