Reversing the size-dependence of surface plasmon resonances.

Journal Article · Tue Aug 17 04:00:00 EDT 2010 · Proc. Natl. Acad. Sci. U.S.A.

DOI:https://doi.org/10.1073/pnas.1007524107· OSTI ID:1018893

Peng, S; McMahon, J M; Schatz, G C; Gray, S K; Sun, Y ^[1]

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1. Center for Nanoscale Materials

The size-dependence of surface plasmon resonances (SPRs) is poorly understood in the small particle limit due to complex physical/chemical effects and uncertainties in experimental samples. In this article, we report an approach for synthesizing an ideal class of colloidal Ag nanoparticles with highly uniform morphologies and narrow size distributions. Optical measurements and theoretical analyses for particle diameters in the d {approx} 2-20 nm range are presented. The SPR absorption band exhibits an exceptional behavior: As size decreases from d {approx} 20 nm it blue-shifts but then turns over near d {approx} 12 nm and strongly red-shifts. A multilayer Mie theory model agrees well with the observations, indicating that lowered electron conductivity in the outermost atomic layer, due to chemical interactions, is the cause of the red-shift. We corroborate this picture by experimentally demonstrating precise chemical control of the SPR peak positions via ligand exchange.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1018893
• Report Number(s): ANL/CNM/JA-67535
• Journal Information: Proc. Natl. Acad. Sci. U.S.A., Journal Name: Proc. Natl. Acad. Sci. U.S.A. Journal Issue: 33 ; Aug. 17, 2010 Vol. 107; ISSN 0027-8424
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ABSORPTION
ELECTRONS
ION EXCHANGE
LIGANDS
PLASMONS
RED SHIFT