Photo-induced enhanced Raman spectroscopy (PIERS): sensing atomic-defects, explosives and biomolecules
Photo-induced enhanced Raman spectroscopy (PIERS): sensing atomic-defects, explosives and biomolecules
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DOI：
10.1117/12.2518948
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发表时间：
2019-05
影响因子：
18.3
通讯作者：
D. Glass;E. Cortés;S. Ben-Jaber;T. Brick;R. Quesada-Cabrera;W. Peveler;Y. Zhu;C. Blackman;C. Howle;I. Parkin;S. Maier
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文献类型：
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作者：
D. Glass;E. Cortés;S. Ben-Jaber;T. Brick;R. Quesada-Cabrera;W. Peveler;Y. Zhu;C. Blackman;C. Howle;I. Parkin;S. Maier
增强的拉曼在很大程度上依赖于找到能够实现显著增强因子的理想热点区域。此外，Sers的所谓“化学增强”方面往往被忽视，因为与电磁（EM）性质的增强因子相比，它的增强因子相对较低。使用金属-半导体混合系统，加上诱导的表面氧空位缺陷，EM和化学增强途径都可以在廉价的可重复使用的表面上使用。两种金属氧化物半导体薄膜，WO 3和TiO 2，被用作研究Au纳米颗粒（NP）的尺寸依赖效应的平台，用于Sers（表面增强拉曼光谱）和PIERS（光诱导增强拉曼光谱-用于附加化学增强的UV预照射）检测应用。将设定浓度的球形Au NP（直径为5、50、100和150 nm）滴铸在预辐照的金属氧化物基底上。以4-巯基苯甲酸（MBA）为拉曼报告分子，发现纳米颗粒的尺寸对Sers测试结果有显著的依赖性，在50 nm的纳米颗粒上，金纳米颗粒的表面覆盖率最大，分布最理想，因此很有可能找到理想的热点区域。然而，更重要的是，PIERS测量也发现对纳米颗粒尺寸的强烈依赖性-完全独立于AuNP分布和取向影响-其中还发现50 nm颗粒产生最大的PIERS增强。分析物分子相对于金属-半导体界面的位置和热点区域内产生的氧空位的位置被提出作为对这一结果的解释。
Enhanced Raman relies heavily on finding ideal hot-spot regions which enable significant enhancement factors. In addition, the termed “chemical enhancement” aspect of SERS is often neglected due to its relatively low enhancement factors, in comparison to those of electromagnetic (EM) nature. Using a metal-semiconductor hybrid system, with the addition of induced surface oxygen vacancy defects, both EM and chemical enhancement pathways can be utilized on cheap reusable surfaces. Two metal-oxide semiconductor thin films, WO3 and TiO2, were used as a platform for investigating size dependent effects of Au nanoparticles (NPs) for SERS (surface enhanced Raman spectroscopy) and PIERS (photo-induced enhanced Raman spectroscopy – UV pre-irradiation for additional chemical enhancement) detection applications. A set concentration of spherical Au NPs (5, 50, 100 and 150 nm in diameter) was drop-cast on preirradiated metal-oxide substrates. Using 4-mercaptobenzoic acid (MBA) as a Raman reporter molecule, a significant dependence on the size of nanoparticle was found. The greatest surface coverage and ideal distribution of AuNPs was found for the 50 nm particles during SERS tests, resulting in a high probability of finding an ideal hot-spot region. However, more significantly a strong dependence on nanoparticle size was also found for PIERS measurements – completely independent of AuNP distribution and orientation affects – where 50 nm particles were also found to generate the largest PIERS enhancement. The position of the analyte molecule with respect to the metal-semiconductor interface and position of generated oxygen vacancies within the hot-spot regions was presented as an explanation for this result.