Plasmon Bleaching Dynamics in Colloidal Gold–Iron Oxide Nanocrystal Heterodimers

Abstract

Colloidal nanocrystal heterodimers composed of a plasmonic and a magnetic domain have been widely studied as potential materials for various applications in nanomedicine, biology, and photocatalysis. One of the most popular nanocrystal heterodimers is represented by a structure made of a Au domain and a iron oxide domain joined together. Understanding the nature of the interface between the two domains in such type of dimer and how this influences the energy relaxation processes is a key issue. Here, we present the first broad-band transient absorption study on gold/iron oxide nanocrystal heterodimers that explains how the energy relaxation is affected by the presence of such interface. We found faster electron-electron and electron-phonon relaxation times for the gold "nested" in the iron oxide domain in the heterodimers with respect to gold "only" nanocrystals, that is, free-standing gold nanocrystals in solution. We relate this effect to the decreased electron screening caused by spill-out of the gold electron distribution at gold/iron oxide interface.

Metal/Semiconductor Hybrid Nanostructures for Plasmon‐Enhanced Applications

“…Understanding and controlling the charge‐transfer behavior across the interface junction in the hybrid nanostructures is essential for various plasmon‐enhanced catalytic reactions. So far, the role of the interface has been studied only in a few experiments using femtosecond transient absorption spectroscopy . More research is clearly required along this direction.…”

“…Iron oxides possess attractive magnetic properties, and are biocompatible. Iron oxides in different phases and morphologies have been integrated with plasmonic metals to create Janus nanostructures . A simple chemical method has been developed for preparing dumbbell‐like bifunctional Au/Fe 3 O 4 nanostructures (Figure d) .…”

Reversible Modulation of Surface Plasmons in Gold Nanoparticles Enabled by Surface Redox Chemistry

“…In contrast, for the reduced core–shell nanoparticles, the PA spectra are more symmetric, as shown in Figure 5 B. Especially at a delay time of 1.33 ps, the features for this sample are almost the same as pure Au nanoparticles, with a bleach at the resonance position and similar PA intensity at both sides of the SPR peak position 16. The divergent TA features from oxidized and reduced core–shell nanoparticles suggest that hot electrons are likely injected into the shells of the oxidized core–shell nanoparticles to reduce FeO x into Fe, leading to a dramatic change of the relaxation dynamics of the excited Au SPs.…”

Controlled growth of plasmonic heterostructures and their applications

“…For asymmetric metal-semiconductor heterocrystals with both components exposed to the outside, the reactive hotspots, metal plasmons and quantum-confined electronic states in the semiconductor nanostructures are tactfully integrated in one nanosystem [135][136][137][138][139]. Great efforts have been made to explore the physical and chemical properties observed with asymmetric heterostructures [140][141][142][143][144][145][146]. An abundance of synergistic properties from the asymmetric heterocrystals have received wide attention, such as the heterojunction-induced photogenerated carrier separation, the plasmon-enhanced sunlight harvesting and the plasmon-induced hot-electron transfer from metal nanostructures into strong coupled semiconductors [147][148][149][150].…”