63 research outputs found
Nonlinear plasmonics at high temperatures
We solve the Maxwell and heat equations self-consistently for metal
nanoparticles under intense continuous wave (CW) illumination. Unlike previous
studies, we rely on {\em experimentally}-measured data for the metal
permittivity for increasing temperature and for the visible spectral range. We
show that the thermal nonlinearity of the metal can lead to substantial
deviations from the predictions of the linear model for the temperature and
field distribution, and thus, can explain qualitatively the strong nonlinear
scattering from such configurations observed experimentally. We also show that
the incompleteness of existing data of the temperature dependence of the
thermal properties of the system prevents reaching a quantitative agreement
between the measured and calculated scattering data. This modelling approach is
essential for the identification of the underlying physical mechanism
responsible for the thermo-optical nonlinearity of the metal and should be
adopted in all applications of high temperature nonlinear plasmonics,
especially for refractory metals, both for CW and pulsed illumination
The photothermal nonlinearity in plasmon-assisted photocatalysis
We show that the temperature rise in large ensembles of metal nanoparticles
under intense illumination is dominated by the temperature dependence of the
thermal conductivity of the host, rather than by the optical properties of the
metal or the host. This dependence typically causes the temperature rise to
become sublinear, with this photothermal nonlinear effect becoming unusually
strong, reaching even several tens of percent. We then show that this can
explain experimental observations in several recent plasmon-assisted
photocatalysis experiments. This shows that any claim for dominance of
non-thermal electrons in plasmon-assisted photocatalysis must account for this
photothermal nonlinear mechanism
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