John B. Ketterson

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Transmission electron microscopy (TEM) observations of graphite tubules (buckytubes) and their derivatives have revealed not only the previously reported buckytube geometries but also additional shapes of the buckytube derivatives. Detailed cross-sectional TEM images reveal the cylindrical cross section of buckytubes and the growth pattern of buckytubes as(More)
Most organic radicals possess short lifetimes and quickly undergo dimerization or oxidation. Here, we report on the synthesis by radical templation of a class of air- and water-stable organic radicals, trapped within a homo[2]catenane composed of two rigid and fixed cyclobis(paraquat-p-phenylene) rings. The highly energetic octacationic homo[2]catenane,(More)
The various decay mechanisms of excitons in cuprous oxide (Cu 2 O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing that the samples have few defects. Some locations, however, show strain splitting of(More)
We present results on the in situ, two-dimensional growth ͑as opposed to the more commonly encountered island-coalescence mechanism͒ of continuous epitaxial Cu 2 O films on MgO͑011͒ using dc facing-magnetron sputtering from metallic Cu targets in an oxygen/argon atmosphere. Film growth was studied as a function of deposition time and the dc power applied to(More)
We fabricated bismuth ͑Bi͒ nanowires with low energy electron beam lithography using silver ͑Ag͒ nanocrystal shadowmasks and a subsequent chlorine reactive ion etching. Submicron-size metal contacts on the single Bi nanowire were successfully prepared by in situ focused ion beam metal deposition for transport measurements. The temperature dependent(More)
The efficiency of third-harmonic generation in cuprous oxide was measured. Intensities followed a noncubic power law that indicates nonperturbative behavior. Polarization anisotropy of the harmonic generation was demonstrated and related to the third-order susceptibility. The results will influence the understanding of harmonic generation in centrosymmetric(More)
We report measurements of the attenuation of a beam of orthoexciton polaritons by a photoionizing optical probe. Excitons were prepared in a narrow resonance by two photon absorption of a 1.016 eV, 54 ps pulsed light source in cuprous oxide (Cu 2 O) at 1.4 K. A collinear, 1.165 eV, 54 ps probe delayed by 119 ps was used to measure the photoionization cross(More)
Nonlinear optical responses of materials play a vital role for the development of active nanophotonic and plasmonic devices. Optical nonlinearity induced by intense optical excitation of mobile electrons in metallic nanostructures can provide large-amplitude, dynamic tuning of their electromagnetic response, which is potentially useful for all-optical(More)
Phase-pure cuprous oxide (Cu2O) crystals are difficult to grow since cupric oxide can form within the crystal as the crystal is cooled to ambient conditions. Vacancies are the solute which causes precipitation of macroscopic defects. Therefore, even when a mostly phase-pure single crystal is used as a feed rod, cupric oxide inclusions persist in the(More)
largely directed at measurements of the optical properties of the semiconductor cuprous oxide (Cu 2 O), including the preparation of relatively large (∼3/8 ") single crystal specimens on which the measurements were made. Synthesis was carried out using: i) oxidation of copper, ii) crystallization from melt with the optical floating zone method, and iii)(More)