第149回先端計測オープンセミナー

2019年10月31日 (木) 15:00-16:00

国立研究開発法人 物質・材料研究機構
千現地区 研究本館8階 中セミナー室

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Prof. Zhenchao Dong
Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China

STM-based single-molecule optical spectroscopy

The nanocavity defined by the coinage-metal tip and substrate in a scanning tunneling microscope (STM) can provide highly localized and dramatically enhanced electromagnetic fields upon proper plasmonic resonant tuning, which can modify the excitation and emission of a single molecule inside the nanocavity and produce intriguing new optoelectronic phenomena. In this talk, I shall demonstrate two STM-based phenomena related to single-molecule optical spectroscopy. The first is single-molecule Raman scattering [1]. The spatial resolution of tip enhanced Raman spectromicroscopy has been further driven down to a single chemical-bond scale. Such simultaneous energetically and spatially resolved capability for vibrational-mode mapping opens up a new possibility to determine molecular chemical structure by optical imaging at only a single molecule. The second phenomenon is single-molecule electroluminescence [2]. Our recent research on its excitation mechanism and single-photon emission behavior will be briefly presented. I shall also demonstrate how sub-nanometer resolved electroluminescence imaging can be used to gain insights into the intramolecular vibronic coupling and intermolecular dipole-dipole coupling in real space.

References:
1. R. Zhang, Y. Zhang, Z. C. Dong*, S. Jiang, C. Zhang, L. G. Chen, L. Zhang, Y. Liao, J. Aizpurua, Y. Luo, J. L. Yang, and J. G. Hou*, Nature 498, 82-85 (2013).
2. Y. Zhang, Y. Luo, Y. Zhang, Y. J. Yu, Y. M. Kuang, L. Zhang, Q. S. Meng, Y. Luo, J. L. Yang, Z. C. Dong*, and J. G. Hou*, Nature 531, 623-627 (2016).