Extinction vs Absorption: Which Is the Indicator of Plasmonic Field Strength for Silver Nanocubes?

TitleExtinction vs Absorption: Which Is the Indicator of Plasmonic Field Strength for Silver Nanocubes?
Publication TypeJournal Article
Year of Publication2012
AuthorsNear, R, Hayden, S, El-Sayed, M
JournalJournal of Physical Chemistry C
Date PublishedNov
ISBN Number1932-7447
Accession NumberWOS:000310482900046

This investigation demonstrates the contributions of absorption and scattering to the extinction spectrum of silver nanocubes with multipole resonances and the complexity of the resulting plasmon field strengths for these varying modes. The three-dimensional plasmonic field distribution and orientation around a silver nanosphere (AgNS; 40 nm) and a silver nanocube (AgNC; 40, 60, 86 nm) were calculated in the visible via the discrete dipole approximation. The three-dimensional nature of these particles allows for significant contribution from the quadrupole mode in some cases. The AgNS displays one plasmon band, its dipole mode, and has little contribution from scattering. The maximum plasmon field occurs at the extinction maximum, as expected. The 40 nm AgNC exhibits multiple plasmon bands, and the highest maximum field strength is attained from excitation of the quadrupole mode, not the dipole mode. As the size of the AgNC increases, the contribution from scattering increases. When the contribution from scattering is greater than the contribution from absorption in a AgNC, the field strength within a plasmon mode trends with the absorption and not with the extinction or cattering. This should be considered in applications of AgNCs, as excitation of the largest peak in the experimental extinction spectrum will not always result in the strongest plasmon field strength.