Nano-Materials (3)量子尺寸效应：当粒子的尺寸达到纳米量级时，费米能级附 近的电子能级由连续态分裂成分立能级。当能级间距大于热能、磁 能、静电能、静磁能、光子能或超导态的凝聚能时，会出现纳米材 料的量子效应，从而使其磁、光、声、热、电、超导电性能变化。 量子点-Quantum dots What is a quantum dot? ·Nanocrystals ·2-10 nm diameter ·semiconductors Core-Shell EviDot
Nano-Materials （3）量子尺寸效应：当粒子的尺寸达到纳米量级时，费米能级附 近的电子能级由连续态分裂成分立能级。当能级间距大于热能、磁 能、静电能、静磁能、光子能或超导态的凝聚能时，会出现纳米材 料的量子效应，从而使其磁、光、声、热、电、超导电性能变化。 量子点-Quantum dots
Nano-Materials 量子点(Quantum dots:the band gaps of a quantum dot will change greatly when its diameter is adjusted between 1-10 nm CB As particle gets smaller, the band gap gets bigger. E VB Semiconductor
Nano-Materials 量子点(Quantum dots): the band gaps of a quantum dot will change greatly when its diameter is adjusted between 1- 10 nm As particle gets smaller, the band gap gets bigger
Quantum Dots-量子点 Small size Cd;P2(Eg:~3.0ev): No visible light absorbed. CB As particle Q-Cd3P2 gets smaller, VB the band gap gets bigger. Semiconductor Big size Cd;P2(E:0.5 ev):absorb all wavelength of visible light
Quantum Dots -量子点 Small size Cd3P2 ( Eg: ~ 3.0 eV): No visible light absorbed. Big size Cd3P2 (Eg: 0.5 eV): absorb all wavelength of visible light. As particle gets smaller, the band gap gets bigger
量子点-Quantum Dots 光致发光-Photoluminescence Quantum Dots Ultraviolet Ultraviolet light off light on Quantum dot 00 Quantum Quantum dots bead dots emit light 10 10 Water Nanodevices White molecule Quantum dots blood cell
量子点- Quantum Dots 光致发光---Photoluminescence
量子点-Quantum Dots 光致发光-Photoluminescence Simultaneous excitation at 365 nm 2nm CS 7nm Size-dependent emission When illuminated with ultraviolet light,these solution of semiconductor nano-particles emit light that correspond to their band gap energy. 400450500550600 650700 Wavelength,(nm)
量子点- Quantum Dots 光致发光---Photoluminescence CdS When illuminated with ultraviolet light, these solution of semiconductor nano-particles emit light that correspond to their band gap energy