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Photo-induced enhanced Raman spectroscopy (PIERS): sensing atomic-defects, explosives and biomolecules
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Paper Abstract

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.

Paper Details

Date Published: 17 May 2019
PDF: 10 pages
Proc. SPIE 11010, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XX, 110100D (17 May 2019); doi: 10.1117/12.2518948
Show Author Affiliations
D. Glass, Imperial College London (United Kingdom)
Univ. College London (United Kingdom)
E. Cortés, Ludwig-Maximilians-Univ. München (Germany)
Imperial College London (United Kingdom)
S. Ben-Jaber, Univ. College London (United Kingdom)
T. Brick, Imperial College London (United Kingdom)
R. Quesada-Cabrera, Univ. College London (United Kingdom)
W. J. Peveler, Univ. of Glasgow (United Kingdom)
Y. Zhu, Univ. College London (United Kingdom)
C. S. Blackman, Univ. College London (United Kingdom)
C. R. Howle, Defence Science and Technology Lab. (United Kingdom)
I. P. Parkin, Univ. College London (United Kingdom)
S. A. Maier, Ludwig-Maximilians-Univ. München (Germany)
Imperial College London (United Kingdom)


Published in SPIE Proceedings Vol. 11010:
Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XX
Jason A. Guicheteau; Chris R. Howle, Editor(s)

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