Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.
J Am Chem Soc. 2021 Mar 3;143(8):3060-3064. doi: 10.1021/jacs.1c00542. Epub 2021 Feb 17.
Single-molecule methods have revolutionized molecular science, but techniques possessing the structural sensitivity required for chemical problems-e.g. vibrational spectroscopy-remain difficult to apply in solution. Here, we describe how coupling infrared-vibrational absorption to a fluorescent electronic transition (fluorescence-encoded infrared (FEIR) spectroscopy) can achieve single-molecule sensitivity in solution with conventional far-field optics. Using the fluorophore Coumarin 6, we illustrate the principles by which FEIR spectroscopy measures vibrational spectra and relaxation and introduce FEIR correlation spectroscopy, a vibrational analogue of fluorescence correlation spectroscopy, to demonstrate single-molecule sensitivity. With further improvements, FEIR spectroscopy could become a powerful tool for single-molecule vibrational investigations in the solution or condensed phase.
单分子方法已经彻底改变了分子科学，但是具有化学问题所需的结构敏感性的技术——例如振动光谱——仍然难以在溶液中应用。在这里，我们描述了如何将红外振动吸收与荧光电子跃迁相结合（荧光编码红外（FEIR）光谱），从而在传统的远场光学中实现溶液中单分子的灵敏度。我们使用荧光团香豆素 6 来说明 FEIR 光谱测量振动光谱和弛豫的原理，并引入 FEIR 相关光谱，这是荧光相关光谱的振动类似物，以证明单分子灵敏度。通过进一步的改进，FEIR 光谱可能成为溶液或凝聚相中单分子振动研究的有力工具。
