bon nanotubes, which is in the range of 800±1900. [22] In general, the field enhancement factor is approximated by the length-to-radius ratio (L/r) of a nanowire. [21] The average radius of a nanowire estimated from the FEGSEM image is about 20 nm (Fig. 1b). Thus, the length of the AlQ 3 nanowires is calculated to be 5.5 lm, similar to the thickness of the nanowire layer. This value is reasonable because the AlQ 3 nanowires are grown from the substrate in a dendritic configuration and rolled up to a layer of thickness about several micrometers. In summary, AlQ 3 nanowires and nanobelts were first synthesized by vapor condensation. Although the AlQ 3 molecules are bonded by relatively weak van der Waals forces, the flexibility and the field emission current density of the nanowires are higher than expected. This provides a new choice of materials for field emission. The potential applications will be of great interest for future study. ExperimentalAlQ 3 nanowires and nanobelts were grown by a vapor condensation system, which consisted of a cylindrical Pyrex vessel (200 mm long, 200 mm diameter, and 7 mm thick) sandwiched by two 304 stainless steel plates [11]. The concave shaped steel plate on the top was filled with liquid nitrogen to act as a cold trap. A graphite boat was employed as a resistive heater, and the temperature was regulated by a power supply and controlled by a K-type thermocouple. AlQ 3 powder (purchased from TCI Ltd., T1527) was put in the graphite boat. A substrate was placed under the liquid nitrogen cold trap. The chamber was evacuated to 1.0 10 ±3 Pa, and argon was then introduced to the chamber. Typical argon pressure and boat temperature were set at 133 Pa and 400 C, respectively. The temperature of the graphite boat was raised to the working temperature at a rate of 40 C min , and the cathode was the AlQ 3 nanowires deposited on an ITOcoated glass substrate. The field emission instrumentation had a sphere-to-plate geometry rather than plane-to-plane because the platinum probe provided precise motion and manipulation in the high vacuum. Therefore, the field emission properties in any region of the nanowires could be measured. The high voltage was supplied by a power source (Keithley 237) with an accuracy of 10 ±13 A, and the current under increasing applied voltage was recorded. In addition to its well-known importance to biology, deoxyribonucleic acid (DNA), as a one-dimensional macromolecule, has attracted interest as a material for use in functional mesoscopic electronic devices [1,2] and in molecular computing. [3,4] The p-electron overlap between the base pairs within the double helix implies that the stacked base pairs might be a one-dimensional pathway for electronic charge transport. [5,6] Although the transport properties of DNA have been studied, [7±10] a wide range of results have been reported with properties spanning the full range from insulating [11,12] to semiconducting [13,14] to metallic [15] and even to superconducting behavior. [16] Thus, the electronic propert...
Using an atomic force microscope, we studied various InAs-on-AlSb interface structures grown by molecular beam epitaxy. We found marked differences between the effects of the two interface bond configurations—InSb-like and AlAs-like—on the morphology of the subsequent InAs layer. In general, InSb-like interfaces lead to a much smoother InAs overgrown layer with clearly resolvable monolayer terraces. AlAs-like interfaces, on the other hand, lead to increasingly rougher InAs growth with longer As exposure. Previous studies have demonstrated a strong correlation between the interface configuration and the electron mobility in the InAs quantum well. The morphology and transport results we obtained indicate one reason for the influence of the interface configuration—a rough InAs layer.
We introduce a “high-impedance ground plane” (HIGP) substrate for use in single-molecule imaging applications. The HIGP is a quarter-wave-thick layer of dielectric material is deposited over a regular metallic mirror. Comparison of confocal fluorescence images of single DiI molecules on HIGP substrates and on glass substrates indicates a dramatic increase in the number of collected photons for the HIGP substrate. Signal enhancement ranges from a factor of 8 at low excitation powers to a lifetime-limited factor of 2 at higher powers.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.