Effect of Morphology on Ultrafast Carrier Dynamics in Asymmetric Gold–Iron Oxide Plasmonic Heterodimers

Understanding how nanoscale interfaces affect electrical and optical properties of multifunctional nanocrystal heterostructures is of paramount importance for their technological application. In this context, we investigated the ultrafast carrier dynamics of rodlike gold–iron oxide nanocrystal heterodimers, in a spectral region close to the surface plasmon resonance frequency, by means of broad-band transient absorption spectroscopy. We found that the electron–phonon relaxation time is independent of the morphology of the iron oxide domain. Moreover, we revealed a transient shift in the surface plasmon resonance frequency, which can be related to charge transfer at the interface between gold and iron oxide.