*Correspondence: Timothy S. Fisher , Birck Nanotechnology Center, 1205 West State Street, West Lafayette, IN 47907, USA e-mail: [email protected] This article describes advances in thermionic and photo-emission materials and applications dating back to the work on thermionic emission by Guthrie (1873) and the photoelectric effect by Hertz (1893). Thermionic emission has been employed for elec...

The competition between electron emission and unimolecular dissociation following the absorption of a single photon is studied for small clusters of various elements. Electron emission results from either direct photoemission, observed as a series of peaks in the spectrum, or thermionic emission, giving rise to a continuous background. Depending on the energetics involved, thermionic emission i...

In this paper for the first time a precise theoretical analysis of efficiencies and power densities for nano-scaled thermionic vacuum gap devices is presented. Plane electrodes with nano-gaps will be treated first. With nonplanar electrodes (nanotips) enhanced electron field emission occurs, giving rise to new design options. The theories of field and thermionic emission are combined by calcula...

Diamond-based low-work function thermionic electron emitters are in high demand for applications ranging from electron guns and space thrusters to electrical energy converters. A key requirement of such diamond-based electron sources is hydrogen termination of the surfaces which can significantly reduce the emission barrier. However, at high temperatures (≤600°C), terminated hydrogen begins to ...

Thermionic electron emission forms the basis of both electron sources for a variety of applications and a direct energy conversion process that is compact and scalable. The present study characterizes thermionic emission from boron-doped nanocrystalline diamond films with hydrogen and nitrophenyl surface termination layers. A hemispherical energy analyzer was used to measure electron energy dis...

Using a nanomanipulation system contained within a scanning electron microscope we investigate the thermionic electron emission from multiwall carbon nanotubes. Peak emission currents of 65 nA are measured. The carbon nanotubes being grown at low temperature by the chemical vapor deposition method are defective with poor thermal conductivity. We believe it is crucial for the thermal conductivit...

We present measurements of the velocity distribution of electrons emitted from mass-selected neutral fullerenes, performed at the intracavity free electron laser FELICE. We make use of mass-specific vibrational resonances in the infrared domain to selectively heat up one out of a distribution of several fullerene species. Efficient energy redistribution leads to decay via thermionic emission. T...

In this paper, electron emission from non-planar potential barrier structures is analyzed using a Monte Carlo electron transport model. Compared to the planar structures, about twice bigger emission current can be achieved for the non-planar tall barriers. The thermionic emission enhancement is attributed to combined effects of increased effective interface area and reduced probability of total...

A brief overview of the research activities at the Thermionic Energy Conversion (TEC) Center is given. The goal is to achieve direct thermal to electric energy conversion with >20% efficiency and >1W/cm power density at a hot side temperature of 300-650C. Thermionic emission in both vacuum and solid-state devices is investigated. In the case of solid-state devices, hot electron filtering using ...