Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.
Analyst. 2013 Apr 21;138(8):2323-8. doi: 10.1039/c3an36841f.
We show that single gold nanorods can act as highly sensitive mercury vapor sensors with attogram resolution. We exposed assorted gold nanorods, with aspect ratios ranging from 2.8-4.1, to μg m(-3) concentrations of mercury vapor in air for 1 hour. Pre- and post-exposure, the nanorods were examined with a combination of dark field spectroscopy and transmission electron microscopy. Because we isolated individual particles, we can describe the shape and size effects distinctly rather than statistically (a constraint of studying heterogeneous nanoparticle films). No measurable changes occurred to the shape and size of the nanorods due to their saturation with mercury vapor. The localized surface plasmon resonance (LSPR) of the mercury-saturated nanorods blue shifted 2.6-3.8 nm; the magnitude of the shift depended on the initial shape and size of the nanorod. Larger aspect ratios and surface-area-to-volume ratios both enhance the LSPR shift seen in saturated nanoparticles. The predictions of a core-shell model mirrors the shape and size effects observed experimentally. These results increase our understanding of mercury-adsorption by gold surfaces, and help to optimize nanoparticle-based plasmonic mercury sensing.
我们证明，单根金纳米棒可以作为具有纳克级分辨率的高灵敏度汞蒸气传感器。我们将各种长径比为 2.8-4.1 的金纳米棒暴露于空气中μg m(-3)浓度的汞蒸气中 1 小时。在暴露前后，我们使用暗场光谱和透射电子显微镜对纳米棒进行了检查。由于我们分离了单个颗粒，因此可以清晰地描述形状和尺寸效应，而不是进行统计描述（这是研究异质纳米颗粒膜的一个限制）。由于汞蒸气的饱和作用，纳米棒的形状和尺寸没有发生可测量的变化。汞饱和纳米棒的局域表面等离子体共振（LSPR）蓝移了 2.6-3.8nm；位移的大小取决于纳米棒的初始形状和尺寸。较大的长径比和表面积与体积比都增强了饱和纳米颗粒中观察到的 LSPR 位移。核壳模型的预测反映了实验观察到的形状和尺寸效应。这些结果增加了我们对金表面吸附汞的理解，并有助于优化基于纳米粒子的等离子体汞传感。
