Plasmonic nanostructures offer great potential as functional components in photonic materials. However, the optical and electronic properties of these materials depend on nanoscale structural effects. The inherent structural heterogeneity of metal nanoparticles renders determination of structure-photonic function relations difficult. Moreover, plasmon dynamics are short lived (typically 10s of femtoseconds). Ultrafast correlated light and electron microscopy (UCLEM), which combines interferometric nonlinear optical (INLO) and electron microscopy imaging techniques, can provide these structure-property correlations. INLO has both single-nanoparticle sensitivity and few-optical-cycle temporal resolution for examining structure-dependent dynamics. Here, a series of constant-volume gold nanorods with different aspect ratios were used as model systems to study the structure-dependent electronic behavior in single nanoparticles. UCLEM data revealed that detuning the plasmon resonance and interband transition energies resulted in systematic increases in plasmon coherence time. These studies were extended to multi-particle assemblies that support Fano resonances. The results show that Fano excitation can lead to approximate 3x increases in plasmon coherence times due to suppression of radiative decoherence pathways. In summary, these results demonstrate the capability of UCLEM approaches to quantify structure-specific electronic relaxation dynamics, which are critical precursors for the rational design of photonic materials.  <br/>

Single-nanostructure electron dynamics studied using ultrafast correlated light and electron microscopy (UCLEM)

256th National Meeting (2018)

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