Individual nanostructures often have a unique spectral response associated with the interplay of intrinsic material properties and extrinsic size, shape, orientation, and the local environment. Characterization of the relationship of these parameters to the electronic properties of the nanostructure is often obscured in traditional transient absorption and 2D spectroscopy measurements, as larger focal sizes sample an ensemble of nanostructures averaging over local variations in the electronic response.<br/><br/>In order to isolate the local response of a single nanostructure, we have constructed a Two-Dimensional White Light (2D-WL) microscope coupled with an Atomic Force Microscope (AFM). Here, topographical characterization in the AFM allows for precise characterization of the microscope focal spot size and identification of isolated nanostructures targeted for 2D-WL characterization.<br/><br/>For our measurements a compressed broadband white light continuum encompassing the visible range (460-1300 nm) was used as both pump and probe enabling characterization of broad electronic states. As a means of overcoming the lower signal volume associated with isolated structures, we take advantage of the near-diffraction limited focal volume of the microscope objective and implement a high repetition rate laser source as a means boosting the signal-to-noise ratio. Measurements are performed at 100 kHz with both shot-to-shot pulse shaping and detection, enabling the spectral features of isolated semiconducting and molecular nanostructures to be clearly resolved.

Ultrafast 2D white light spatial imaging of single nano-structures

253rd National Meeting (2017)

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