The Photon Factory, The University of Auckland, Auckland 1010, New Zealand.
Department of Chemical and Materials Engineering, The University of Auckland, Auckland 1010, New Zealand.
J Phys Chem Lett. 2023 May 18;14(19):4607-4616. doi: 10.1021/acs.jpclett.3c00478. Epub 2023 May 11.
Photoinduced enhanced Raman spectroscopy (PIERS) is a new surface enhanced Raman spectroscopy (SERS) modality with a 680% Raman signal enhancement of adsorbed analytes over that of SERS. Despite the explosion in recent demonstrations, the PIERS mechanism remains undetermined. Using X-ray and time-resolved optical spectroscopies, electron microscopy, cyclic voltammetry, and density functional theory simulations, we elucidate the atomic-scale mechanism behind PIERS. Stable PIERS substrates were fabricated using self-organized arrays of TiO nanotubes with controlled oxygen vacancy doping and size-controlled silver nanoparticles. The key source of PIERS vs SERS enhancement is an increase in the Raman polarizability of the adsorbed analyte upon photoinduced charge transfer. A balance between improved crystallinity, which enhances charge transfer due to higher electron mobility but decreases light absorption, and increased oxygen vacancy defect concentration, which increases light absorption, is critical. This work enables the rational design of PIERS substrates for sensing.
光诱导增强拉曼光谱（PIERS）是一种新的表面增强拉曼光谱（SERS）模态，与 SERS 相比，吸附分析物的拉曼信号增强了 680%。尽管最近的演示出现了爆炸式增长，但 PIERS 机制仍未确定。本研究使用 X 射线和时间分辨光学光谱学、电子显微镜、循环伏安法和密度泛函理论模拟，阐明了 PIERS 背后的原子尺度机制。使用具有受控氧空位掺杂和尺寸控制的银纳米粒子的自组织 TiO 纳米管阵列制造了稳定的 PIERS 基底。PIERS 与 SERS 增强的关键来源是光致电荷转移导致吸附分析物的拉曼极化率增加。改善结晶度（由于电子迁移率更高而增强电荷转移，但降低光吸收）和增加氧空位缺陷浓度（增加光吸收）之间的平衡至关重要。这项工作使 PIERS 基底的合理设计能够用于传感。
