Eckhoff Dean A, Sutin Jason D B, Clegg Robert M, Gratton Enrico, Rogozhina Elena V, Braun Paul V
Department of Physics and Laboratory for Fluorescence Dynamics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, USA.
J Phys Chem B. 2005 Oct 27;109(42):19786-97. doi: 10.1021/jp052214e.
Studying the properties and stability of silicon nanoparticles (Si-np) in aqueous environments may lead to novel applications in biological systems. In this work, we use absorption and photoluminescence (PL) spectroscopy to characterize ultrasmall Si-np prepared through anodic etching and ultrasonic fractionation of a crystalline Si wafer. Their behavior is studied over time in 2-propanol and during treatments with water, NaOH, HCl, and H(2)O(2). The observed population is divided into two types of material: bright species consisting of well-etched Si-np, approximately 1 nm in diameter, and dark species derived from partially etched or aggregated Si structures. The dark material is seen by its scattering in the 2-propanol and water solutions and is largely removed via precipitation with the NaOH or HCl treatment. The bright material includes three distinct species with their respective emissions in the UV-B, UV-A, and hard-blue regions of the spectrum. The hard-blue PL is shown to have a simple pH dependence with a pK(a) approximately 3, providing an important insight into its chemical origin and signaling for possible application of Si-np as environmental probes. Our results offer some potential for tailoring the PL properties of ultrasmall Si-np through control of their surface chemistry.
研究硅纳米颗粒（Si-np）在水性环境中的性质和稳定性可能会带来生物系统中的新应用。在这项工作中，我们使用吸收光谱和光致发光（PL）光谱来表征通过对晶体硅片进行阳极蚀刻和超声分级制备的超小Si-np。我们研究了它们在异丙醇中随时间的行为以及在用水、NaOH、HCl和H₂O₂处理过程中的行为。观察到的物质分为两种类型：一种是由蚀刻良好的直径约为1 nm的Si-np组成的明亮物质，另一种是源自部分蚀刻或聚集的硅结构的暗物质。暗物质在异丙醇和水溶液中通过散射可见，并且通过用NaOH或HCl处理沉淀而大部分被去除。明亮物质包括三种不同的物质，它们在光谱的UV-B、UV-A和硬蓝区域有各自的发射。硬蓝PL显示出与pH的简单依赖性，pKₐ约为3，这为其化学起源提供了重要见解，并表明Si-np有可能作为环境探针应用。我们的结果为通过控制其表面化学来调整超小Si-np的PL性质提供了一些潜力。
