Ultrafast Dynamics of Single ZnO Nanowires using Ultraviolet Femtosecond Kerr-gated Wide-field Fluorescence Microscopy

The ultrafast temporal dynamics of a single ZnO nanowire is probed using an ultraviolet femtosecond Kerr- gated wide field fluorescence microscope. The microscope is a comprehensive tool that not only operates in steady state and transient mode but can also function as both an ultrafast imaging instrument as well as a femtosecond fluorescence spectrometer. The sub 90 femtosecond temporal resolution and sub micron spatial resolution facilitate the measurement of ultrafast dynamics of single nanostructures. The steady state and temporal emission from a single ZnO nanowire is observed at different fluences. At high fluences the carrier density exceeds that of the Mott density and bandgap renormalization is observed in the transient spectra. Morphological anomalies resulted in enhanced localized emission from regions along the nanowire. Selective area analysis facilitated extraction of emission dynamics from a single region on the nanowire and provided insight into how structural inhomogeneities affect ultrafast phenomenon occurring in a single nanowire.