Search results for "Field electron emission"

Asymmetric tungsten oxide nanobrushes via oriented attachment and Ostwald ripening

2011

Tungsten oxide nanobrushes were synthesized using a solvothermal approach that lead to self-branching in the presence of citric acid and hexadecylamine as surfactants. Our synthetic approach yielded branched nanorods of tungsten oxide in a single synthetic step. Based on our results, we propose a phenomenological pathway for the formation, branching, and assembly of these tungsten oxide brushes. The formation of tungsten oxide brushes proceeds by thermal decomposition of ammonium tungstate in the presence of citric acid and hexadecylamine. The pale blue powder obtained after solvothermal reaction was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolu…

Synergistic effect between hydrodynamic conditions during Ti anodization and acidic treatment on the photoelectric properties of TiO2 nanotubes

2015

In the present work, the combined influence of controlled hydrodynamic conditions during Ti anodization and the acidic treatment with HClO4 on the photoelectric properties of mixed anatase/rutile TiO2 nanotubes has been studied. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FE-SEM), Confocal Raman Microscopy, electrochemical measurements (electrochemical impedance spectroscopy and Mott-Schottky analysis) and photoelectrochemical measurements. It has been observed that the use of hydrodynamic conditions increases the surface area of nanotubes, while acidic treatment enhances their conductivity. Besides, there is a clear synergistic effect between t…

Field Emission of Electrons Generated by the Near Field of Strongly Coupled Plasmons

2012

Field emission of electrons is generated solely by the ultrastrong near-field of strongly coupled plasmons without the help of a noticeable dc field. Strongly coupled plasmons are excited at Au nanoparticles in subnanometer distance to a Au film by femtosecond laser pulses. Field-emitted electrons from individual nanoparticles are detected by means of photoelectron emission microscopy and spectroscopy. The dependence of total electron yield and kinetic energy on the laser power proves that field emission is the underlying emission process. We derive a dynamic version of the Fowler-Nordheim equation that yields perfect agreement with the experiment.

Single-component plasma of photoelectrons

2007

Abstract Ten-nanosecond pulses of photoelectrons liberated by intense UV laser pulses from a thin gold layer are captured into a single-component plasma that is ideally suited to cool antiprotons ( p ¯ ) for antihydrogen ( H ¯ ) production. Up to a billion electrons are accumulated using a series of laser pulses, more than are needed for efficient p ¯ cooling in the large traps now being used for loading p ¯ for H ¯ production. The method is demonstrated within an enclosed vacuum space that is entirely at 4 K, and is thus compatible with the exceptional cryogenic vacuum that is desirable for the long-term storage of antihydrogen. The pitfalls of other electron accumulation methods are entir…

Ferromagnetism at the summit: A perspective on: “Spin polarized field emission from Fe and co-coated W tips” by Y.R. Niu and M.S. Altman

2010

Investigation of a Ge nanoparticle film by means of electron stimulated photon emission spectroscopy

2014

Abstract Electron stimulated photon emission spectroscopy was used for the study of the electronic structure of Ge nanoparticles. A nanoparticle film was prepared by thermal deposition on a quartz substrate. Photon emission was stimulated by electron bombardment at energies of several hundred electron volts. Electron field emission from a W-tip was used at tip voltage U t  = 100–600 eV. A spectrometer in combination with a liquid nitrogen cooled charge-coupled device (CCD) camera was used for light detection. Light emission spectra were measured in the energy range 1.18–4.2 eV. They are characterized by features at ∼1.6 and ∼3.1 eV. A comparison with light emission spectra obtained with ano…

Nano-graphite cold cathodes for electric solar wind sail

2015

The nanographite (NG) films consisting of tiny graphite crystallites (nanowalls) are produced by carbon condensation from methane–hydrogen gas mixture activated by a direct current discharge. High aspect ratio and structural features of the NG crystallites provides efficient field electron emission (FE). Applicability and performance of the NG films in an electron gun (E-gun) of a solar wind thruster system with an electric sail (E-sail) is tested. The long-term tests are demonstrated suitability of E-gun assembly with the NG cathodes for the real space missions. The results of the tests are analyzed and physical mechanisms of the cathode aging and practical methods for improvement performa…