1 March 2010 Ultrafast transient absorption studies of single metal and semiconductor nanowires
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Abstract
Single particle transient absorption experiments have been used to study metallic and semiconducting nanowires. For the metal wires the major result is the observation of modulations in the transient absorption traces due to coherently excited breathing modes. The vibrational periods depend on the dimensions of the nanowire, and the decay times are sensitive to the environment. The nanowires in our experiments are spin coated from a polymer solution onto a glass substrate, and experience a range of different environments. This causes large variations in the quality factor of the breathing mode for different wires. Semiconducting nanowires of CdTe and CdSe were also examined. The CdTe wires show fast picosecond time scale dynamics, which are assigned to charge carrier trapping at surface states of the wires. In contrast, CdSe nanowires show no dynamics on the time scale of our measurements. For the CdTe nanowires the charge carrier trapping times vary from wire-to-wire, and also vary with position in a single wire. This is attributed to differences in surface chemistry. Overall these experiments illustrate the important of single particle techniques for studying nanomaterials, especially for elucidating how differences in local environment and structure affect dynamics.
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Gregory V. Hartland, Christopher R. Carey, Hristina Staleva, "Ultrafast transient absorption studies of single metal and semiconductor nanowires", Proc. SPIE 7600, Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIV, 76000D (1 March 2010); doi: 10.1117/12.840920; https://doi.org/10.1117/12.840920
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