Li Xia, Baronio Stefania, Gross Susanne, Haunold Thomas, Vesselli Erik, Rupprechter Günther
Institute of Materials Chemistry, Technische Universität Wien, Getreidemarkt 9/BC, Vienna 1060, Austria.
Physics Department, University of Trieste, Via Valerio 2, Trieste I-34127, Italy.
J Phys Chem C Nanomater Interfaces. 2025 Jul 1;129(27):12551-12560. doi: 10.1021/acs.jpcc.5c02545. eCollection 2025 Jul 10.
Sum frequency generation (SFG) spectroscopy was used to study CO adsorption on smooth and rough Ir(111) single crystal surfaces, the cleanliness, composition, order and morphology of which were comprehensively characterized by Auger electron spectroscopy (AES), low energy ion scattering (LEIS), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). For CO adsorbed on Ir(111), the resonant SFG signal intensity associated with the internal C-O stretch mode was about eight times stronger on a rough termination than on a smooth surface. Herein, we thoroughly discuss the origin of this phenomenon and consider several possible contributing factors, including coverage and lateral interactions, molecular hyperpolarizability (IR dipole moment and Raman polarizability), adsorption geometry (tilt angle), Fermi resonances, adsorbate hot vibrational bands, and surface plasmons and electronic structure. It is concluded that the sputter-induced local roughness of the Ir surface (grains evidenced by STM) facilitates the light-induced excitation of localized surface plasmon resonances (LSPR), accounting for the observed signal enhancement.
和频产生（SFG）光谱被用于研究一氧化碳在光滑和粗糙的Ir(111)单晶表面上的吸附情况，其清洁度、组成、有序性和形态通过俄歇电子能谱（AES）、低能离子散射（LEIS）、低能电子衍射（LEED）和扫描隧道显微镜（STM）进行了全面表征。对于吸附在Ir(111)上的一氧化碳，与内部C-O伸缩模式相关的共振SFG信号强度在粗糙表面上比在光滑表面上大约强八倍。在此，我们深入讨论了这种现象的起源，并考虑了几个可能的影响因素，包括覆盖率和横向相互作用、分子超极化率（红外偶极矩和拉曼极化率）、吸附几何结构（倾斜角）、费米共振、吸附质热振动带以及表面等离子体激元和电子结构。得出的结论是，溅射诱导的Ir表面局部粗糙度（STM显示的晶粒）促进了光诱导的局域表面等离子体共振（LSPR）激发，这解释了观察到的信号增强现象。
