Enhancing the signal strength of surface sensitive 2D IR spectroscopy
Enhancing the signal strength of surface sensitive 2D IR spectroscopy
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DOI：
10.1063/1.5065511
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发表时间：
2019-01-14
影响因子：
4.4
通讯作者：
Zanni, Martin T.
中科院分区：
文献类型：
--
作者：
Petti, Megan K.;Ostrander, Joshua S.;Zanni, Martin T.
能够测量表面和界面的光谱技术必须克服两个技术挑战：一是表面分子的低覆盖率，二是辨别来自本体和表面的信号。我们提出了表面增强衰减反射二维红外（SEAR 2D IR）光谱，这是一种将局域表面等离子体与反射泵浦探针几何结构相结合以实现单层灵敏度的方法。该方法在 6 μm 处用模型肽的酰胺 I 带进行了演示，模型肽是一种半胱氨酸封端的 α 螺旋肽，连接在金表面上。使用 SEAR 2D IR 光谱，该样品的信号在电介质表面的单层上增强了 20 000 倍。与衰减全反射红外光谱一样，SEAR 2D 红外光谱可应用于强吸收溶剂。我们通过用水溶解肽单层来证明这种能力，在测量酰胺 I 带时通常不能使用这种能力。 SEAR 2D 红外光谱将有利于研究电化学表面的化学反应、光伏中的界面电荷转移以及脂膜中跨膜蛋白的结构变化。由 AIP Publishing 许可发布。
Spectroscopic techniques that are capable of measuring surfaces and interfaces must overcome two technical challenges: one, the low coverage of molecules at the surface, and two, discerning between signals from the bulk and surface. We present surface enhanced attenuated reflection 2D infrared (SEAR 2D IR) spectroscopy, a method that combines localized surface plasmons with a reflection pump-probe geometry to achieve monolayer sensitivity. The method is demonstrated at 6 mu m with the amide I band of a model peptide, a cysteine terminated alpha-helical peptide tethered to a gold surface. Using SEAR 2D IR spectroscopy, the signal from this sample is enhanced 20 000-times over a monolayer on a dielectric surface. Like attenuated total reflection IR spectroscopy, SEAR 2D IR spectroscopy can be applied to strongly absorbing solvents. We demonstrated this capability by solvating a peptide monolayer with H2O, which cannot normally be used when measuring the amide I band. SEAR 2D IR spectroscopy will be advantageous for studying chemical reactions at electrochemical surfaces, interfacial charge transfer in photovoltaics, and structural changes of transmembrane proteins in lipid membranes. Published under license by AIP Publishing.