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  • Comparison of Gap-Enhanced Raman Tags and Nanoparticle Aggregates with Polarization Dependent Super-Resolution Spectral SERS Imaging
Title: Comparison of Gap-Enhanced Raman Tags and Nanoparticle Aggregates with Polarization Dependent Super-Resolution Spectral SERS Imaging
Strongly confined electric fields resulting from nanogaps within nanoparticle aggregates give rise to significant enhancement in surface-enhanced Raman scattering (SERS). Nanometer differences in gap sizes lead to drastically different confined field strengths, so much attention has been focused on the development and understanding of nanostructures with controlled gap sizes. In this work, we report a novel petal gap-enhanced Raman tag (GERT) consisting of bipyramid core and a nitrothiophenol (NTP) spacer to support the growth of hundreds of small petals and compare its SERS emission and localization to a traditional bipyramid aggregate. To do this, we used super resolution spectral SERS imaging that simultaneously captures the SERS images and spectra while varying the incident laser polarization. Intensity fluctuations inherent of SERS enabled super resolution algorithms to be applied which revealed sub-diffraction limited differences in the localization with respect to polarization direction for both particles. Interestingly, however, only the traditional bipyramid aggregates experienced a strong polarization dependence in their SERS intensity and in the plasmon-induced conversion of NTP to dimercaptoazobenzene (DMAB), which was localized with nanometer precision to regions of intense electromagnetic fields. The lack of polarization dependence (validated through electromagnetic simulations) and surface reactions from the bipyramid-GERTs suggest that the emissions arising from the bipyramid-GERTs are less influenced by confined fields.  more » « less
Award ID(s):
2107791
PAR ID:
10523505
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
Analytical Chemistry
ISSN:
0003-2700
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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