2025-05-21 分子科学研究所
図１ （ａ）ピコキャビティに閉じ込められたH2およびD2のTERSスペクトル。各スペクトルには回転（rot）、振動（vib）、およびそれらの結合モード（vib + rot）に由来するラマンピークが明瞭に観測されている。（ｂ）（ａ）で観測されたラマンピークに対応する、水素分子の回転および振動のエネルギー準位の遷移を示す模式図。
＜関連情報＞
- https://www.ims.ac.jp/news/2025/05/0521.html
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.206901
物理吸着したH2およびD2分子のピコキャビティ増強ラマン分光法 Picocavity-Enhanced Raman Spectroscopy of Physisorbed H2 and D2 Molecules
Akitoshi Shiotari, Shuyi Liu, George Trenins, Toshiki Sugimoto, Martin Wolf, Mariana Rossi, and Takashi Kumagai
Physical Review Letters Published 20 May, 2025
DOI: https://doi.org/10.1103/PhysRevLett.134.206901
Abstract
We report on tip-enhanced Raman spectroscopy of H2 and D2 molecules physisorbed within a plasmonic picocavity at 10 K. The intense Raman peaks resulting from the rotational and vibrational transitions are observed at subnanometer gap distances of the junction formed by an Ag tip and an Ag(111) surface, where a picocavity-enhanced field plays a crucial role. A significant redshift of the H-H stretch frequency is observed as the gap distance decreases, while the D-D stretch frequency is unaffected. Density functional theory, path-integral molecular dynamics, and quantum anharmonic vibrational energy calculations suggest that this unexpected isotope effect is explained by a different molecular density between H2 and D2 on the surface.
