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Unformatted text preview: Synthesis and fluorescence spectrum analysis of CdS nanocrystals Wanbang Xu Æ Yongxian Wang Æ Ronghui Xu Æ Sheng Liang Æ Guoxin Zhang Æ Duanzhi Yin Received: 10 September 2006 / Accepted: 30 November 2006 / Published online: 26 April 2007 Ó Springer Science+Business Media, LLC 2007 Abstract An optimized synthesis route was applied for control the preparation of CdS nanocrystals (NCs) in an aqueous solution. Some key factors which influencing the characters of CdS NCs, such as stabilizers, ratio of reactant etc, were investigated. It was found that the fluorescence (FL) intensity of CdS NCs could be dramatically enhanced by refluxing. The size, shape, crystal structure and the optical properties of CdS NCs were also characterized by TEM, XRD, UV–Vis and FL spectra. The result showed that the well-disperse spheres CdS NCs with 6 nm in diameter were obtained. Introduction II–VI semiconductor nanocrystals (NCs) have attained a great research focus due to their advantages in optical properties including tunable emission spectra, high photo- stability, resistance to photobleaching and controllable surface characteristics. Studies on potential applications of II–VI NCs to life sciences [ 1 ] had been ignited since the pioneer work of Alivisatos [ 2 ], who fluorescently labeled 3T3 mouse fibroblast cells using two different size CdSe– CdS core-shell NCs enclosed in a silica shell, and Nie [ 3 ], who developed a classical method of nonisotopic detection labels by coupling luminescent CdSe–ZnS NCs to biolog- ical molecules in 1998. CdS, one of the most attractive metal chalcogenides, has been widely used as biomarkers owing to its excellent optical properties [ 4 – 6 ]. Nowaday CdS NCs could be prepared by a number of methods [ 7 , 8 ]. Significant progresses had been made by Peng [ 9 , 10 ] and coworkers, who synthesized strongly luminescent mono- disperse CdS NCs by pyrolysis of precursor injection (or- ganometallics method). The method, however, involves toxic reagents and intermediates (such as Cd (CH 3 ) 2 , TOPO and so on), and the obtained NCs are soluble in just non-polar organic solvents because of the hydrophobic li- gands unless their surfaces are modified. For biological and environmental applications, it is essential to prepare CdS NCs in water directly. In contrast to organometallics techniques, solution reaction growth method appears to be safer, lower cost and more convenient approach [ 11 – 14 ] because it does not involve special instrumentation, poi- sonous intermediates and the growing-rate can be easily controlled. In this work, we reported an optimized route to synthesize CdS NCs with improved FL properties....
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This note was uploaded on 09/30/2010 for the course MADARCHODH Behenchodh taught by Professor Bosardike during the Spring '10 term at École Normale Supérieure.
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