%0 Online Multimedia
%A Mezni, Amine
%A Balti, Imen
%A Mlayah, Adnen
%A Jouini, Noureddine
%A Smiri, Leila
Samia
%D 2016
%T Hybrid Au–Fe3O4 Nanoparticles:
Plasmonic, Surface Enhanced Raman Scattering, and Phase Transition
Properties
%U https://acs.figshare.com/articles/media/Hybrid_Au_Fe_sub_3_sub_O_sub_4_sub_Nanoparticles_Plasmonic_Surface_Enhanced_Raman_Scattering_and_Phase_Transition_Properties/2389066
%R 10.1021/jp4040826.s001
%2 https://acs.figshare.com/ndownloader/files/4028755
%K Optical absorption measurements
%K plasmonic
%K 2O
%K Fe 3O nanoparticles
%K Phase Transition PropertiesIn
%K magnetite Fe 3O nanoparticles
%K phase transition
%K surface plasmon resonance
%K Surface Enhanced Raman Scattering
%K NP
%K iron hydroxide surface layer
%K SERS signal exhibits
%K gold cores act
%X In
this work, we report on the synthesis of hybrid Au–Fe3O4 nanoparticles (NPs) using a novel one-pot synthesis
method that makes use of triethylene glycol as a solvent, a reducing
agent, and a stabilizing layer. The produced nanoparticles consist
of Au cores decorated with magnetite Fe3O4 nanoparticles.
Optical absorption measurements combined with numerical simulations
showed that the Au–Fe3O4 nanoparticles
exhibit a localized surface plasmon resonance clearly red-shifted
with respect to that of bare Au nanoparticles. This strong plasmonic
resonance is exploited to produce surface-enhanced Raman scattering
(SERS) from both the organic molecules and the iron oxide surrounding
the Au cores. We found that the SERS signal exhibits strong temporal
fluctuations which are used to identify the origin of the observed
Raman lines. In particular, we clearly point out the presence of an
iron hydroxide (γ-FeOOH) layer at the surface of the Fe3O4 nanoparticles forming the shell. This result
is supported by numerical simulations of the plasmonic near field
generated by the Raman probe. Moreover, we investigate the light-induced
phase transition from magnetite to hematite (α-Fe2O3). Owing to the strong SERS effect we were able to detect
the formation of diiron-oxo bonds during the phase transition. These
bonds are ascribed to the presence of a mixed magnetite/maghemite
phase. We thus propose a new scheme where the phase transition is
triggered by the iron hydroxide surface layer. Such a transition is
here studied for the first time in Au–Fe3O4 hybrid nanoparticles where the gold cores act as plasmonic nanoheaters
responsible for the thermally induced phase transition.
%I ACS Publications