Surface Plasmon-coupled Emission of Multicolor Quantum Dots
- 化学化工－已发表论文 
[中文文摘]以巯基小分子为配体水相合成CdTe量子点,通过调节回流时间调控其粒径大小.由于量子点的宽谱激发特性,在蓝光(473 nm)或绿光(532 nm)条件下,纳米金属薄膜表面不同发射波长的CdTe量子点均可被激发而与金属表面等离子体发生耦合相互作用,从而在棱镜一侧发出高度定向的偏振荧光,其荧光特性与样品厚度密切相关.表面等离子体耦合荧光发射法(SPCE)具有波长分辨性质,不同颜色的量子点在不同角度定向发射,发射波长越长,角度越小.720nm和630 nm量子点的自由空间发射荧光光谱呈现交叠,然而,基于SPCE的波长分辨性质,我们通过改变检测角度避开光谱重叠,在棱镜一侧的43o和51o处分别得到了两种量子点的SPCE荧光单峰.量子点是SPCE在多通路、高通量检测应用中荧光物种的理想选择.[英文文摘]Aqueous CdTe quantum dots(QDs) were synthesized employing thiols as stabilizing ligands and their emission wavelengths could be tuned by controlling the reflux time.Surface plasmon-coupled emission(SPCE) properties of multicolor CdTe QDs were studied by using a laboratory-built multifunctional spectrofluorimeter.To fabricate a CdTe QDs-doped complete film onto the surface of continuous thin metal films,CdTe QDs were spin-coated at 3000 r/min with poly(vinyl alcohol)(PVA) solution of various concentrations.For SPCE measurements, the spin-coated slides were attached to a semi-cylindrical prism made of fused silica with a refractive-index-matching fluid and then positioned on a precise rotary stage that allowed for excitation and emission observation at any angle relative to the vertical axis of the stage. For excitation, we used the reverse Kretschmann (RK) configuration and the incident light was normal to the sample interface. The spectra were measured using a monochromator equipped with a photomultiplier tube. The experimental results showed CdTe QDs located nearby continuous thin metal film could be excited using either blue (473 nm) or green (532 nm) laser as a result of their broad excitations and their emissions resulting from the surface plasmon coupling were strongly directional, highly polarized and closely related to sample thickness. Because of the wavelength-resolution property of SPCE, CdTe QDs with different emission wavelengths were found to emit at different fixed angles, longer wavelengths corresponding to smaller angles. The free space emission spectra of 720 nm and 630 nm CdTe QDs in a mixture were overlapped and could not be separated at any detection angle. However, owing to the unique wavelength resolution ability of SPCE, the spectra of 720 nm and 630 nm CdTe QDs were obtained at 43° and 51º on the prism side, respectively. The determination of each component of the mixtures of CdTe QDs was achieved by changing the detection angle to avoid spectral overlap. Therefore, QDs are ideal fluorophores for SPCE in high-throughput, multiplex analysis application.