Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada.
Nanotechnology. 2014 Jan 24;25(3):035501. doi: 10.1088/0957-4484/25/3/035501. Epub 2013 Dec 17.
A rapid method of obtaining photoacoustic spectroscopic signals for trace amounts of surface adsorbed molecules using a nanostructured coupled resonator array is described. Explosive molecules adsorbed on a nanoporous anodic aluminum oxide cantilever, which has hexagonally ordered nanowells with diameters and well-to-well distances of 35 nm and 100 nm, respectively, are excited using pulsed infrared (IR) light with a frequency matching the common mode resonance frequency of the coupled resonator. The common mode resonance amplitudes of the coupled resonator as a function of illuminating IR wavelength present a photoacoustic IR absorption spectrum representing the chemical signatures of the adsorbed explosive molecules. In addition, the mass of the adsorbed molecules as an orthogonal signal for quantitative analysis is determined by measuring the variation of the localized, individual mode resonance frequency of a cantilever on the array. The limit of detection of the ternary mixture of explosive molecules (1:1:1 of trinitrotoluene (TNT), cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN)) is estimated to be ~ 100 ng cm(-2). These multi-modal signals enable us to perform quantitative and rapid chemical sensing and analysis in ambient conditions.
本文描述了一种使用纳米结构耦合谐振器阵列快速获取痕量表面吸附分子光声光谱信号的方法。将吸附在具有六角形纳米孔的阳极氧化铝悬臂梁上的爆炸分子（纳米孔的直径和孔间距分别为 35nm 和 100nm）用频率与耦合谐振器公共模式共振频率匹配的脉冲红外光激发。作为照明红外波长函数的耦合谐振器的公共模式共振幅度呈现出光声红外吸收光谱，代表了吸附爆炸分子的化学特征。此外，通过测量阵列上悬臂梁的局部、单个模式共振频率的变化，确定了吸附分子的质量作为定量分析的正交信号。三进制混合爆炸分子（TNT、RDX 和 PETN 的比例为 1:1:1）的检测极限估计约为 100ng/cm^2。这些多模态信号使我们能够在环境条件下进行快速的定量化学传感和分析。
