Mangum Benjamin D, Mu Chun, Gerton Jordan M
Department of Physics, University of Utah, 115 S. 1400 E., Salt Lake City, Utah 84112, USA.
Opt Express. 2008 Apr 28;16(9):6183-93. doi: 10.1364/oe.16.006183.
We investigate the limits of one-photon fluorescence as a contrast mechanism in nanoscale-resolution tip-enhanced optical microscopy. Specifically, we examine the magnitude of tip-induced signal enhancement needed to resolve individual fluorophores within densely-packed ensembles. Modulation of fluorescence signals induced by an oscillating tip followed by demodulation with a lock-in amplifier increases image contrast by nearly two orders of magnitude. A theoretical model of this simple modulation/ demodulation scheme predicts an optimal value for the tip-oscillation amplitude that agrees with experimental measurements. Further, as an important step toward the eventual application of tip-enhanced fluorescence microscopy to the nanoscale structural analysis of biomolecular systems, we show that requisite signal enhancement factors are within the capabilities of commercially available silicon tips.
我们研究了单光子荧光作为纳米级分辨率尖端增强光学显微镜中对比度机制的局限性。具体而言，我们研究了在密集排列的集合体中分辨单个荧光团所需的尖端诱导信号增强幅度。由振荡尖端诱导的荧光信号调制，随后用锁相放大器进行解调，可使图像对比度提高近两个数量级。这种简单调制/解调方案的理论模型预测了与实验测量结果相符的尖端振荡幅度的最佳值。此外，作为将尖端增强荧光显微镜最终应用于生物分子系统纳米级结构分析的重要一步，我们表明所需的信号增强因子在市售硅尖端的能力范围内。
