Near-Field Plasmonic Behavior of Au/Pd Nanocrystals with Pd-Rich Tips

TL;DR

This study shows that Au/Pd nanocrystals with Pd-rich tips can support localized surface plasmon resonances and exhibit strong field enhancement, despite Pd's poor plasmonic properties, revealing complex plasmonic behavior at the nanoscale.

Contribution

It demonstrates that Pd-rich tips in Au/Pd nanocrystals can sustain plasmon resonances and field enhancements, challenging traditional views on material plasmonic suitability.

Findings

Pd-rich tips exhibit strong localized surface plasmon resonances

Au/Pd nanocrystals show size-dependent plasmonic behavior

Substrate and interparticle coupling influence plasmonic responses

Abstract

Using nanometer spatial resolution electron-energy loss spectroscopy (EELS), energy dispersive X-ray spectroscopy (EDS), and cathodoluminescence (CL) mapping, we demonstrate that Au alloys containing a poor plasmonic metal (Pd) can nevertheless sustain multiple size-dependent localized surface plasmon resonances and observe strong field enhancement at Pd-rich tips, where the composition is in fact least favorable for plasmons. These Au/Pd stellated nanocrystals are also involved in substrate and interparticle coupling, as unraveled by EELS tilt series.