<br/>Doped metal oxide nanocrystals exhibit localized surface plasmon resonances (LSPR) at infrared energies which are compositionally tunable through dopant concentration and choice of semiconductor material. Observation of the optical response of plasmonic materials reveals important properties about the behavior of the electron gas such as its charge carrier concentration and electronic mobility. These properties, which can be used to accurately simulate the expected spectral characteristics of these nanocrystals as well as their potential for near field enhancement of electromagnetic radiation, are otherwise immeasurable for individual nanocrystals except via optical investigation. Due to the inherent heterogeneity of doped nanocrystals, single nanocrystal optical responses must be investigated to remove inhomogeneous broadening of ensemble spectra. Synchrotron infrared nano-spectroscopy enables these measurements to be made. This tip enhanced technique takes advantage of both the concentration of infrared light to substantially sub-diffraction limit volumes as well as the broadband light source of the synchrotron to directly measure LSPR. Single nanocrystal measurements reveal LSPR properties consistent with metal oxide nanocrystals having exceptionally high electronic mobility compared to traditional metal nanoparticles. These high mobilities, in addition to the degrees of control offered in materials that have their LSPR modulated through composition rather than morphology, indicate that metal oxides are a strong candidate for mid-infrared plasmonic applications.

Direct observation of localized surface plasmon resonances in single nanocrystals of doped metal oxides

253rd National Meeting (2017)

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