Chemicals induce dipoles to damp plasmons

phys.org | 3/22/2019 | Staff
hakimi308hakimi308 (Posted by) Level 4
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The light scattered by plasmonic nanoparticles is useful, but some of it gets lost at the surface and scientists are now starting to figure out why.

In novel experiments at Rice University and the Johannes Gutenberg University of Mainz, along with theoretical work at Princeton University, researchers found that molecules placed on the surface of a single gold nanorod affect its plasmonic response by altering the electronic structure of the particle itself.

Finding - Applications - Catalysis - Chemistry

The finding could enhance applications like catalysis that involve plasmon-driven chemistry.

Plasmons are ripples of electrons that resonate across the surface of a metal nanoparticle when triggered by light. The light they receive at one wavelength, or color, is radiated at the same wavelength, and that can inform researchers about the particle and its environment.

Surface - Plasmons - Presence - Chemicals - Photochemistry

Surface plasmons help sense the presence of chemicals, enable photochemistry and selectively catalyze chemical reactions. But light lost between the particle's surface and the researcher's eye can contain additional information previously not considered.

It had been thought signal loss via plasmon damping was due to chemicals adsorbed to the nanoparticle surface, perhaps through charge transfer from the metal to the chemical substances. But Stephan Link, a professor of chemistry and of electrical and computer engineering at Rice, had doubts that just one explanation would fit all studies.

Link - Author - Benjamin - Förster - Colleagues

They led Link, lead author Benjamin Förster and their colleagues to the discovery of an entirely different mechanism, reported this week in Science Advances.

Their strategy was to put two types of identically sized molecules with different atomic arrangements onto single gold nanorods for analysis. These molecules, cage-like carborane thiols, induced surface dipoles in the metal that in turn scattered enough of the plasmons' energy to damp their signal.

Researchers - Measure - Interference - Molecules - Nanorods

That let the researchers see and measure damping directly with no interference from other molecules or other nanorods. The proximity of the thiols, identical except...
(Excerpt) Read more at: phys.org
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