The importance of plasmonic heating for the plasmon-driven photodimerization of 4-nitrothiophenol

Metal nanoparticles form potent nanoreactors, driven by the optical generation of energetic electrons and nanoscale heat. The relative influence of these two factors on nanoscale chemistry is strongly debated. This article discusses the temperature dependence of the dimerization of 4-nitrothiophenol...

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Bibliographic Details
Published in:Scientific reports 2019-02, Vol.9 (1), p.3060-3060, Article 3060
Main Authors: Sarhan, Radwan M., Koopman, Wouter, Schuetz, Roman, Schmid, Thomas, Liebig, Ferenc, Koetz, Joachim, Bargheer, Matias
Format: Article
Language:English
Subjects:
140/133
639/301/299/890
639/624/399/354
639/638/77/890
639/925/927/1021
Chemistry
Debates
Dimerization
Experiments
Gold
Heat
Heating
High temperature
Humanities and Social Sciences
multidisciplinary
Nanoparticles
Science
Science (multidisciplinary)
Temperature effects
Temperature preferences
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Summary:Metal nanoparticles form potent nanoreactors, driven by the optical generation of energetic electrons and nanoscale heat. The relative influence of these two factors on nanoscale chemistry is strongly debated. This article discusses the temperature dependence of the dimerization of 4-nitrothiophenol (4-NTP) into 4,4′-dimercaptoazobenzene (DMAB) adsorbed on gold nanoflowers by Surface-Enhanced Raman Scattering (SERS). Raman thermometry shows a significant optical heating of the particles. The ratio of the Stokes and the anti-Stokes Raman signal moreover demonstrates that the molecular temperature during the reaction rises beyond the average crystal lattice temperature of the plasmonic particles. The product bands have an even higher temperature than reactant bands, which suggests that the reaction proceeds preferentially at thermal hot spots. In addition, kinetic measurements of the reaction during external heating of the reaction environment yield a considerable rise of the reaction rate with temperature. Despite this significant heating effects, a comparison of SERS spectra recorded after heating the sample by an external heater to spectra recorded after prolonged illumination shows that the reaction is strictly photo-driven. While in both cases the temperature increase is comparable, the dimerization occurs only in the presence of light. Intensity dependent measurements at fixed temperatures confirm this finding.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-38627-2