title: Reversible Modulation of Surface Plasmons in Gold Nanoparticles Enabled by Surface Redox Chemistry.
abstract: Switchable surface redox chemistry is demonstrated in gold@iron/iron oxide core-shell nanoparticles with ambient oxidation and plasmon-mediated reduction to modulate the oxidation state of shell layers. The iron shell can be oxidized to iron oxide through ambient oxidation, leading to an enhancement and red-shift of the gold surface plasmon resonance (SPR). This enhanced gold SPR can drive reduction of the iron oxide shell under broadband illumination to reversibly blue-shift and significantly dampen gold SPR absorption. The observed phenomena provide a unique mechanism for controlling the plasmonic properties and surface chemistry of small metal nanoparticles.
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA).
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA).
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Foley
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA).
authors.forename: Sheng
authors.initials: S
authors.lastname: Peng
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory (USA).
authors.forename: Cheng-Jun
authors.initials: CJ
authors.lastname: Sun
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory (USA).
authors.forename: Yang
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA). wiederrecht@anl.gov.
authors.forename: Gary P
authors.initials: GP
authors.lastname: Wiederrecht
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA). gray@anl.gov.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Gray
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA). ygsun@anl.gov.
authors.forename: Yugang
authors.initials: Y
authors.lastname: Sun
keywords: core-shell nanoparticles; gold nanocrystals; iron; surface plasmon resonance; surface redox chemistry