Sackrow Marcus, Stanciu Catrinel, Lieb M Andreas, Meixner Alfred J
Institute of Physical and Theoretical Chemistry, Universität Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
Chemphyschem. 2008 Feb 1;9(2):316-20. doi: 10.1002/cphc.200700723.
A novel near-field optical microscope based on a parabolic mirror is used for recording high-resolution tip-enhanced photoluminescence (PL) and Raman images with unprecedented sensitivity and contrast. The measurements reveal small islands on the Au surface with dimensions of only a few nanometres with locally enhanced Au PL. These islands appear as nanometre-sized hot spots in tip-enhanced Raman microscopy when benzotriazole molecules adsorbed on the Au surface serve as local sensors for the optical field. The spectra show that localized plasmons are the cause of both the locally enhanced Au PL and enhanced Raman scattering. This finding suggests that the dispersive background in the surface-enhanced Raman spectra can be explained simply by the enhanced Au PL in the gap. Furthermore, our results show that the surface flatness must be better than 1 nm, to provide an optically homogeneous substrate for near-field enhanced PL and Raman spectroscopy.
一种基于抛物面镜的新型近场光学显微镜，用于记录具有前所未有的灵敏度和对比度的高分辨率尖端增强光致发光（PL）和拉曼图像。测量结果揭示了金表面上尺寸仅为几纳米的小岛，其具有局部增强的金PL。当吸附在金表面的苯并三唑分子用作光场的局部传感器时，这些岛在尖端增强拉曼显微镜中表现为纳米尺寸的热点。光谱表明，局域等离子体是局部增强金PL和增强拉曼散射的原因。这一发现表明，表面增强拉曼光谱中的色散背景可以简单地由间隙中增强的金PL来解释。此外，我们的结果表明，表面平整度必须优于1nm，才能为近场增强PL和拉曼光谱提供光学均匀的基底。
