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Main Authors: Sugimoto, Toshiki, Ichii, Tomoaki, Kanai, Tsuneto, Yoshizawa, Ryu, Takahashi, Shota, Sakurai, Atsunori, Seto, Keisuke, Chengxiang, Jin
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.01442
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author Sugimoto, Toshiki
Ichii, Tomoaki
Kanai, Tsuneto
Yoshizawa, Ryu
Takahashi, Shota
Sakurai, Atsunori
Seto, Keisuke
Chengxiang, Jin
author_facet Sugimoto, Toshiki
Ichii, Tomoaki
Kanai, Tsuneto
Yoshizawa, Ryu
Takahashi, Shota
Sakurai, Atsunori
Seto, Keisuke
Chengxiang, Jin
contents Coherent Raman scattering provides highly sensitive vibrational analysis through nonlinear light-matter interactions. However, its application to metal interfaces has remained challenging because the intrinsically large non-resonant background (NRB) of metals overwhelms weak interfacial molecular vibrational signals, making direct Raman detection without plasmonic or electronic enhancement highly challenging. Here, we report a time-frequency hybrid coherent Raman spectroscopy approach that overcomes this limitation and enables sensitive detection of ångström-thick molecular systems even on atomically flat metal surfaces. Our method employs a time-frequency engineered detection scheme that combines femtosecond pump and Stokes pulses with a time-delayed, asymmetrically shaped picosecond probe pulse. By exploiting instantaneous temporal response of the metal NRB, this pulse configuration effectively filters out the dominant metal NRB in the time domain while retaining a controlled residual NRB that acts as an internal local oscillator, enabling strong interferometric amplification of weak interfacial vibrational signatures. This all-optical coherent enhancement strategy establishes a new route for direct, non-invasive Raman detection of interfacial molecular systems across a wide range of surfaces without requiring structure- and material-specific plasmonic and electronic enhancement mechanisms.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01442
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Plasmonic- and Electronic-Enhancement-Free Coherent Raman Detection of Ångström-Scale Molecular Layers at Metal Interfaces
Sugimoto, Toshiki
Ichii, Tomoaki
Kanai, Tsuneto
Yoshizawa, Ryu
Takahashi, Shota
Sakurai, Atsunori
Seto, Keisuke
Chengxiang, Jin
Optics
Materials Science
Coherent Raman scattering provides highly sensitive vibrational analysis through nonlinear light-matter interactions. However, its application to metal interfaces has remained challenging because the intrinsically large non-resonant background (NRB) of metals overwhelms weak interfacial molecular vibrational signals, making direct Raman detection without plasmonic or electronic enhancement highly challenging. Here, we report a time-frequency hybrid coherent Raman spectroscopy approach that overcomes this limitation and enables sensitive detection of ångström-thick molecular systems even on atomically flat metal surfaces. Our method employs a time-frequency engineered detection scheme that combines femtosecond pump and Stokes pulses with a time-delayed, asymmetrically shaped picosecond probe pulse. By exploiting instantaneous temporal response of the metal NRB, this pulse configuration effectively filters out the dominant metal NRB in the time domain while retaining a controlled residual NRB that acts as an internal local oscillator, enabling strong interferometric amplification of weak interfacial vibrational signatures. This all-optical coherent enhancement strategy establishes a new route for direct, non-invasive Raman detection of interfacial molecular systems across a wide range of surfaces without requiring structure- and material-specific plasmonic and electronic enhancement mechanisms.
title Plasmonic- and Electronic-Enhancement-Free Coherent Raman Detection of Ångström-Scale Molecular Layers at Metal Interfaces
topic Optics
Materials Science
url https://arxiv.org/abs/2603.01442