Shiotari Akitoshi, Liu Shuyi, Trenins George, Sugimoto Toshiki, Wolf Martin, Rossi Mariana, Kumagai Takashi
Fritz-Haber Institute of the Max-Planck Society, Department of Physical Chemistry, Faradayweg 4-6, 14195 Berlin, Germany.
Max-Planck-Institute for Structure and Dynamics of Matter, 22761 Hamburg, Germany.
Phys Rev Lett. 2025 May 23;134(20):206901. doi: 10.1103/PhysRevLett.134.206901.
We report on tip-enhanced Raman spectroscopy of H_{2} and D_{2} 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 H_{2} and D_{2} on the surface.
我们报道了在10K下，吸附在等离子体皮秒腔体内的H₂和D₂分子的针尖增强拉曼光谱。由转动和振动跃迁产生的强烈拉曼峰在由银针尖和Ag(111)表面形成的结的亚纳米间隙距离处被观测到，其中皮秒腔增强场起着关键作用。随着间隙距离减小，观测到H-H伸缩频率有显著红移，而D-D伸缩频率不受影响。密度泛函理论、路径积分分子动力学和量子非谐振动能量计算表明，这种意外的同位素效应可由表面上H₂和D₂之间不同的分子密度来解释。
