Shutova Mariia, Sinyukov Alexander M, Birmingham Blake, Zhang Zhenrong, Sokolov Alexei V
Opt Lett. 2020 Jul 1;45(13):3709-3712. doi: 10.1364/OL.394548.
Surface-enhanced Raman scattering (SERS) spectroscopy is a popular technique for detecting chemicals in small quantities. Rough metallic surfaces with nanofeatures are some of the most widespread and commercially successful substrates for efficient SERS measurements. A rough metallic surface creates a high-density random distribution of so-called "hot spots" with local optical field enhancement causing Raman signal to increase. In this Letter, we revisit the classic SERS experiment [Surf. Sci.158, 229 (1985)SUSCAS0039-602810.1016/0039-6028(85)90297-3] with rough metallic surfaces covered by a thin layer of copper phthalocyanine molecules. As a modification to the classic configuration, we apply an adaptive wavefront correction of a laser beam profile. As a result, we demonstrate an increase in brightness of local SERS hot spots and redistribution of Raman signal over the substrate area. We hypothesize that the improvement is due to optimal coupling of the shaped laser beam to the random plasmonic nanoantenna configurations. We show that the proposed adaptive-SERS modification is independent of the exact structure of the surface roughness and topography, works with many rough surfaces, and gives brighter Raman hot spots in comparison with conventional SERS measurements. We prove that the adaptive SERS is a powerful instrument for improving SERS sensitivity.
表面增强拉曼散射（SERS）光谱法是一种用于检测微量化学物质的常用技术。具有纳米特征的粗糙金属表面是进行高效SERS测量最广泛且商业上最成功的一些基底。粗糙金属表面会产生所谓“热点”的高密度随机分布，局部光场增强导致拉曼信号增加。在本信函中，我们重新审视经典的SERS实验[《表面科学》158, 229 (1985)SUSCAS0039 - 602810.1016/0039 - 6028(85)90297 - 3]，该实验中粗糙金属表面覆盖有一层酞菁铜分子。作为对经典配置的一种改进，我们对激光束轮廓进行自适应波前校正。结果，我们展示了局部SERS热点亮度的增加以及拉曼信号在基底区域的重新分布。我们推测这种改进是由于整形后的激光束与随机等离子体纳米天线配置的最佳耦合。我们表明所提出的自适应SERS改进与表面粗糙度和形貌的确切结构无关，适用于许多粗糙表面，并且与传统SERS测量相比能给出更亮的拉曼热点。我们证明自适应SERS是提高SERS灵敏度的有力工具。
