Dynamic spatial control of MOF position is obtained by incorporating carbon‐coated cobalt nanoparticles within metal organic framework (MOF)‐5 crystals. The cobalt framework composite obtained responds efficiently to magnetic stimuli. A luminescent functionality is added, showing that multifunctional MOF devices can be prepared. This new generation of adaptive material is tested as a position‐controlled molecular sensor.
The incorporation of highly luminescent core-shell quantum dots (QDs) within a metal-organic framework (MOF) is achieved through a one-pot method. Through appropriate surface functionalization, the QDs are solubilized within MOF-5 growth media. This permits the incorporation of the QDs within the evolving framework during the reaction. The resulting QD@MOF-5 composites are characterized using X-ray fluorescence, cross-sectional confocal microscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and small-angle X-ray scattering. The synergistic combination of luminescent QDs and the controlled porosity of MOF-5 in the QD@MOF-5 composites is harnessed within a prototype molecular sensor that can discriminate on the basis of molecular size.
The generation of single event transients generated by the impact of high-energy ions in high-speed photodetectors leads to bit error rate degradation in optical communications in radiation hard environments such as space. High-energy heavy ions, in particular, generate a submicron electron-hole pair plasma with a picosecond temporal profile that results in ultrahigh-injection carrier dynamics which induce large space-charge effects. These space-charge effects disturb the local electric field, thereby determining the peak and duration of a single event transient. In this paper, we examine the transient response of Si p-i-n photodetectors irradiated with focused single MeV heavy ions for a range of ion energies chosen to ensure the same end of range but different average plasma densities. We discuss the role of high-injection effects on the evolving spatiotemporal response with the aid of three-dimensional technology computer-aided design software. The result of both measurement and simulation points to charge collection being dominated by three clearly separable phases: (a) an ultrafast bandwidth-limited response which follows the excitation function, (b) an ambipolar diffusion-dominated expansion phase where space-charge screening limits the extracted current, and (c) a bipolar phase where the external field penetrates the electron-hole pair plasma resulting in rapid collection by drift.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.