Infrared-responsive doped metal oxide nanocrystals are an emerging class of plasmonic materials whose localized surface plasmon resonances (LSPR) can be resonant with molecular vibrations. This presents a distinctive opportunity to manipulate light–matter interactions to redirect chemical or spectroscopic outcomes through the strong local electric fields they generate. Here we report a technique for measuring single nanocrystal absorption spectra of doped metal oxide nanocrystals, revealing significant spectral inhomogeneity in their mid-infrared LSPRs. Our analysis suggests dopant incorporation is heterogeneous beyond expectation based on a statistical distribution of dopants. The broad ensemble linewidths typically observed in these materials result primarily from sample heterogeneity and not from strong electronic damping associated with lossy plasmonic materials. In fact, single nanocrystal spectra reveal linewidths as narrow as 600 cm−1 in aluminium-doped zinc oxide, a value less than half the ensemble linewidth and markedly less than homogeneous linewidths of gold nanospheres.
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机译:红外响应掺杂金属氧化物纳米晶体是一类新兴的等离子体材料,其局部表面等离子体共振(LSPR)可以与分子振动共振。这提供了一个独特的机会来操纵光与物质的相互作用,从而通过它们产生的强局部电场来重定向化学或光谱结果。在这里,我们报告了一种用于测量掺杂金属氧化物纳米晶体的单纳米晶体吸收光谱的技术,该技术揭示了其中红外LSPR中明显的光谱不均匀性。我们的分析表明,根据掺杂剂的统计分布,掺杂剂的掺入异质性超出了预期。通常在这些材料中观察到的宽整体线宽主要是由于样品的异质性,而不是由于与有损耗的等离激元材料相关的强电子阻尼。实际上,单纳米晶体光谱显示掺杂铝的氧化锌的线宽窄至600 cm -1 sup>,其值小于整体线宽的一半,并且显着小于金纳米球的均匀线宽。
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