Takele Wassie Mersha, Piatkowski Lukasz, Wackenhut Frank, Gawinkowski Sylwester, Meixner Alfred J, Waluk Jacek
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Phys Chem Chem Phys. 2021 Aug 12;23(31):16837-16846. doi: 10.1039/d1cp01863a.
Strong coupling between vibrational transitions and a vacuum field of a cavity mode leads to the formation of vibrational polaritons. These hybrid light-matter states have been widely explored because of their potential to control chemical reactivity. However, the possibility of altering Raman scattering through the formation of vibrational polaritons has been rarely reported. Here, we present the Raman scattering properties of different molecules under vibrational strong coupling conditions. The polariton states are clearly observed in the IR transmission spectra of the coupled system for benzonitrile and methyl salicylate in liquid phase and for polyvinyl acetate in a solid polymer film. However, none of the studied systems exhibits a signature of the polariton states in the Raman spectra. For the solid polymer film, we have used cavities with different layer structures to investigate the influence of vibrational strong coupling on the Raman spectra. The only scenario where alterations of the Raman spectra are observed is for a thin Ag layer being in direct contact with the polymer film. This shows that, even though the system is in the vibrational strong coupling regime, changes in the Raman spectra do not necessarily result from the strong coupling, but are caused by the surface enhancement effects.
振动跃迁与腔模真空场之间的强耦合导致振动极化激元的形成。由于这些混合光物质态具有控制化学反应性的潜力，因此已得到广泛研究。然而，通过形成振动极化激元来改变拉曼散射的可能性鲜有报道。在此，我们展示了不同分子在振动强耦合条件下的拉曼散射特性。在液相中的苯甲腈和水杨酸甲酯以及固体聚合物薄膜中的聚醋酸乙烯酯的耦合系统的红外透射光谱中清晰地观察到了极化激元态。然而，在所研究的系统中，没有一个在拉曼光谱中表现出极化激元态的特征。对于固体聚合物薄膜，我们使用了具有不同层结构的腔体来研究振动强耦合对拉曼光谱的影响。观察到拉曼光谱发生改变的唯一情况是薄银层与聚合物薄膜直接接触。这表明，即使系统处于振动强耦合状态，拉曼光谱的变化不一定源于强耦合，而是由表面增强效应引起的。
