2026-05-08 分子科学研究所
図1．時間領域測定と周波数領域測定を融合した表面・界面コヒーレントラマン分光法。従来のラマン測定で必要とされていたプラズモン電場増強や電子共鳴を用いることなく、オングストロームスケールの極薄分子系の計測を可能にした。
＜関連情報＞
「プラズモン増強・電子共鳴に頼らない金属界面オングストロームスケール分子層のコヒーレントラマン検出」 Plasmonic- and Electronic-Enhancement-Free Coherent Raman Detection of Ångström-Scale Molecular Layers at Metal Interfaces
Toshiki Sugimoto,Tomoaki Ichii,Tsuneto Kanai,Ryu Yoshizawa,Shota Takahashi,Atsunori Sakurai,Keisuke Seto,Chengxiang Jin
Nano Letters Published: April 27, 2026
DOI:https://doi.org/10.1021/acs.nanolett.6c00802
Abstract
Coherent Raman scattering provides highly sensitive vibrational analysis through nonlinear light-matter interactions. However, its application to metal interfaces remains challenging because the intrinsically large nonresonant background (NRB) of metals overwhelms weak interfacial molecular vibrational signals. Here, we report a time-frequency hybrid coherent Raman spectroscopy approach that overcomes this limitation and enables the sensitive detection of ångström-thick molecular systems even on atomically flat metal surfaces. Our method combines a femtosecond pump and Stokes pulses with a time-delayed, asymmetrically shaped picosecond probe pulse. By exploiting the instantaneous temporal response of the metal NRB, this scheme effectively filters out the dominant NRB while retaining a controlled residual NRB that acts as an internal local oscillator, enabling the interferometric amplification of weak interfacial vibrational signatures. This all-optical coherent enhancement strategy establishes a route for direct, noninvasive Raman detection of interfacial molecular systems across diverse surfaces without requiring structure- and material-specific plasmonic and electronic enhancement mechanisms.
