Single-molecule infrared spectroscopy with scanning tunneling microscopy

• 成果类型: Article
• 署名作者: Liang, Kangkai; Wang, Zihao; Quan, Weike; Shi, Yueqing; Zhou, Hao; Bi, Liya; Yin, Zhiyuan; Romero, Nathan; Young, Mark; Li, Shaowei
• 署名单位: University of California System; University of California San Diego; University of California System; University of California San Diego; University of California System; University of California San Diego
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8075; 1095-9203
• DOI: 10.1126/science.adz6643
• 发表日期: 2026-02-19
• 页码: 807-811
• 关键词: ABSORPTION-SPECTROSCOPY; relaxation; SURFACES; SPECTRA

摘要

Probing vibrations at the single-molecule level is essential for achieving bond-specific chemical control in realistic heterogeneous environments. Here, we introduce a new measurement scheme that integrates frequency-tunable infrared excitation with scanning tunneling microscopy to characterize vibration-mediated nuclear motions of single molecules. We first validated the technique by monitoring the infrared-induced rotation of the ethynyl radical and then applied it to mapping pyrrolidine's conformational dynamics. The resulting broadband spectra captured fundamental vibrational modes together with rich overtone and combination bands inaccessible by conventional methods, which we confirmed with isotopic substitutions. Density functional theory calculations showed that delocalized modes coupled with pyrrolidine ring puckering drive the structural transition, revealing altered selection rules compared with traditional infrared spectroscopy. This new experimental platform enables molecular vibrations and transformations to be probed with atomic precision.