title: Modulation of Cu(2-x)S Nanocrystal Plasmon Resonance through Reversible Photoinduced Electron Transfer.
abstract: Copper sulfide (Cu(2-x)S) nanocrystals with nonstoichiometric composition exhibit plasmon resonance in the near-infrared region. Compositional changes and varying electron density markedly affect the position and intensity of the plasmon resonance. We report a photochemically induced phenomenon of modulating the plasmon resonance in a controlled fashion. As photogenerated reduced methyl viologen radicals transfer electrons to Cu(2-x)S in inert solutions, we observe a decrease in localized surface plasmon resonance (LSPR) absorbance at 1160 nm. Upon exposure to air, the plasmon resonance band recovers as stored electrons are scavenged away by oxygen. This cycle of electron charge and discharge of Cu(2-x)S nanocrystals is reversible and can be repeated through photoirradiation in N2 saturated solution followed by exposure of the suspension to air. The spectroscopic studies that provide mechanistic insights into the reversible charging and discharging of plasmonic Cu(2-x)S are discussed.
authors: Radiation Laboratory and the Department of Chemistry & Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Rabeka
authors: R
authors: Alam
authors: Radiation Laboratory and the Department of Chemistry & Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Molly
authors: M
authors: Labine
authors: Edgewood Chemical Biological Center, U.S. Army Research, Development and Engineering Command , 5183 Blackhawk Road, APG, Aberdeen, Maryland 21010, United States.
authors: Christopher J
authors: CJ
authors: Karwacki
authors: Radiation Laboratory and the Department of Chemistry & Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Prashant V
authors: PV
authors: Kamat
keywords: copper sulfide; electron transfer; methyl viologen; plasmon resonance; semiconductor nanocrystals