posted on 2020-04-01, 14:43authored byAndrew
R. Salmon, Marie-Elena Kleemann, Junyang Huang, William M Deacon, Cloudy Carnegie, Marlous Kamp, Bart de Nijs, Angela Demetriadou, Jeremy J. Baumberg
The properties of nanoplasmonic structures
depend strongly on their
geometry, creating the need for high-precision control and characterization.
Here, by exploiting the low activation energy of gold atoms on nanoparticle
surfaces, we show how laser irradiation reshapes nanoparticle dimers.
Time-course dark-field microspectroscopy allows this process to be
studied in detail for individual nanostructures. Three regimes are
identified: facet growth, formation of a conductive bridge between
particles, and bridge growth. Electromagnetic simulations confirm
the growth dynamics and allow measurement of bridge diameter, found
to be highly reproducible and also self-limiting. Correlations in
spectral resonances for the initial and final states give insight
into the energy barriers for bridge growth. Dark-field microscopy
shows that coalescence of multiple gaps in nanoparticle clusters can
be digitally triggered, with each gap closing after discrete increases
in irradiation power. Such control is important for light-induced
nanowire formation or trimming of electronic and optoelectronic devices.