Gryczynski Ignacy, Malicka Joanna, Jiang Wen, Fischer Hans, Chan Warren C W, Gryczynski Zygmunt, Grudzinski Wojciech, Lakowicz Joseph R
Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
J Phys Chem B. 2005 Jan 27;109(3):1088-93. doi: 10.1021/jp046173i.
We studied surface plasmon-coupled emission (SPCE) of semiconductor quantum dots (QDs). These QDs are water-soluble ZnS-capped CdSe nanoparticles stabilized using lysine cross-linked mercaptoundecanoic acid. The QDs were spin-coated from 0.75% PVA solution on a glass slide covered with 50 nm of silver and a 5-nm protective SiO(2) layer. Excited QDs induced surface plasmons in a thin silver layer. Surface plasmons emitted a hollow cone of radiation into an attached hemispherical glass prism at a narrow angle of 48.5 degrees. This directional radiation (SPCE) preserves the spectral properties of QD emission and is highly p-polarized irrespective of the excitation polarization. The SPCE spectrum depends on the observation angle because of the intrinsic dispersive properties of SPCE phenomenon. The remarkable photostability can make QDs superior to organic fluorophores when long exposure to the intense excitation is needed. The nanosize QDs also introduce a roughness near the metal layer, which results in a many-fold increase of the coupling of the incident light to the surface plasmons. This scattered incident illumination transformed into directional, polarized radiation can be used simultaneously with SPCE to develop devices based on both quantum dot emission and light scattered from surface plasmons on a rough surface.
我们研究了半导体量子点（QDs）的表面等离子体耦合发射（SPCE）。这些量子点是用水溶性的、用赖氨酸交联巯基十一烷酸稳定的硫化锌包覆的硒化镉纳米颗粒。量子点从0.75%的聚乙烯醇（PVA）溶液旋涂在覆盖有50纳米银和5纳米二氧化硅（SiO₂）保护层的载玻片上。受激发的量子点在薄银层中诱导表面等离子体。表面等离子体以48.5度的窄角向附着的半球形玻璃棱镜发射空心辐射锥。这种定向辐射（SPCE）保留了量子点发射的光谱特性，并且无论激发偏振如何都具有高度的p偏振。由于SPCE现象的固有色散特性，SPCE光谱取决于观察角度。当需要长时间暴露在强激发下时，量子点显著的光稳定性使其优于有机荧光团。纳米尺寸的量子点还会在金属层附近引入粗糙度，这导致入射光与表面等离子体的耦合增加许多倍。这种转化为定向、偏振辐射的散射入射照明可以与SPCE同时使用，以开发基于量子点发射和粗糙表面上表面等离子体散射光的器件。
