Two-Dimensional Fano Lineshapes in Ultrafast Vibrational Spectroscopy of Thin Molecular Layers on Plasmonic Arrays
Two-Dimensional Fano Lineshapes in Ultrafast Vibrational Spectroscopy of Thin Molecular Layers on Plasmonic Arrays
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DOI：
10.1021/acs.jpclett.7b01490
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发表时间：
2017-07-20
影响因子：
5.7
通讯作者：
Chuntonov, Lev
中科院分区：
文献类型：
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作者：
Gandman, Andrey;Mackin, Robert;Chuntonov, Lev
二维飞秒红外（2DIR）光谱通常可以深入了解1-100 μ m厚的块状样品的分子结构和超快动力学。在纳米尺度上，分子被限制在表面、缝隙、裂缝和其他地形特征上，会显著改变它们的结构和动力学，影响其物理和化学性质。在金属纳米结构周围用等离子体增强场放大2DIR信号，可以对受限分子进行结构和动力学测量。由激光脉冲、等离子体激元和振动模式之间的相互作用引起的法诺共振显著地扭曲了二维线形。对于等离子体共振的不同失谐，多个信号分量之间的干扰导致不同的线形不对称，我们在一组线性吸收，瞬态吸收和2DIR光谱上证明了这一点。一个直观的模型用来描述实验数据点的干扰的起源。我们的研究结果将促进表面增强2DIR光谱在纳米环境下分子结构和动力学研究中的应用。
Two-dimensional femtosecond infrared (2DIR) spectroscopy routinely provides insights into molecular structure and ultrafast dynamics in 1-100 mu m thick bulk samples. Confinement of molecules to surfaces, gaps, crevices, and other topographic features, frequently encountered on the nanometer length scale, significantly alters their structure and dynamics, affecting physical and chemical properties. Amplification of 2DIR signals by the plasmon-enhanced fields around metal nanostructures can permit structural and dynamics measurements of the confined molecules. Fano resonances, induced by the interaction between laser pulses, plasmon, and vibrational modes significantly distort 2D lineshapes. For different detuning from plasmon resonance, the interference between multiple signal components leads to different line shape asymmetry, which we demonstrate on a set of linear absorption, transient absorption, and 2DIR spectra. An intuitive model used to describe experimental data points to the interference's origin. Our results will facilitate the application of surface-enhanced 2DIR spectroscopy for studies of molecular structure and dynamics in a nanoconfined environment.