"In plasmonics, we use individual nanoparticles as building blocks to make higher-order structures," Link said. "Here, we're taking concepts known to polymer scientists to analyze the structures of longer chains of nanoparticles that we think resemble polymers."
"The fundamental definition of a polymer is that it's a long molecule whose properties depend on the repeat unit," Slaughter said. "If you change the atoms that repeat in the chain, then you change the properties of the polymer."
"What we changed in our assembly structures was the repeat unit a single particle row versus a dimer (in the double row) and we found that this fit the analogy with chemical polymers because that change very clearly alters the interactions along the chain," Link added.
This basic structure change from a single row to a double row led to pronounced differences demonstrated by additional subradiant modes and a lower energy super-radiant mode.
Two additional interesting effects seemed to be universal among the team's plasmonic polymers. One was that the energy of the super-radiant mode, which results from the interaction over the most repeat units, would characteristically decrease with the addition of nanoparticles along the length, up to about 10 particles, and then level off. "Once you have 10 repeat units, you basically see an optical spectrum that will not change very much if you make a chain with 20 or 50 repeat units," Link said.
The other was that disorder amon
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