In this paper we present a detailed theory of electron and thermoelectric transport perpendicular to heterostructure superlattices. This nonlinear transport regime above barriers is also called heterostructure thermionic emission. We show that metal-based superlattices with tall barriers can achieve a large effective thermoelectric figure of merit (ZT > 5 at room temperature). A key parameter t...

Photoelectron velocity-map imaging and electronic structure calculations have been used to study the temporary anion (resonance) dynamics of the closed-shell site-specific deprotonated tetracene anion (C18H11(-)) in the hv = 3.26 eV (380 nm) to 4.13 eV (300 nm) range. In accord with a recent frequency-, angle-, and time-resolved photoelectron imaging study on a related but open-shell polyaromat...

The general purpose of our research program is to study problems relating to the atomic, molecular, and electronic processes occurring at gas -solid interfaces. Examples of these processes are: thermionic emission, surface ionization, adsorption, absorption, oxidation, catalysis by metals, electrode processes in electrical discharges, and the scattering of molecular beams from solid surfaces. S...

Thermionic energy conversion, a process that allows direct transformation of thermal to electrical energy, presents a means of efficient electrical power generation as the hot and cold side of the corresponding heat engine are separated by a vacuum gap. Conversion efficiencies approaching those of the Carnot cycle are possible if material parameters of the active elements at the converter, i.e....

Preparation procedures and thermionic emission properties of graphitic carbon nanofibres (GCNFs) supported on Si wafer or commercial carbon felt supports are reported. GCNF/native-oxide Si wafer, GCNF/oxidized Si wafer, GCNF/Ni-coated Si wafer and GCNF/carbon felt nanocomposites are obtained by growing GCNFs from growth catalyst nanoparticles supported on these supports. Narrow herringbone GCNF...

Probing the validity of classical macroscopic physical laws at the nanoscale is important for nanoscience research. Herein, we report on experimental evidence that electron emission from individual hot carbon nanotubes (CNTs) heated by self-Joule-heating does not obey Richardson's law of thermionic emission. By using an in-situ multi-probe measurement technique, electron emission density (J) an...

Thin film thermionic coolers use selective emission of hot electrons over a heterostructure barrier layer from emitter to collector resulting in evaporative cooling. In this paper a detailed theory of electron transport perpendicular to the multilayer superlattice structures is presented. Using Fermi-Dirac statistics, density-of-states for a finite quantum well and the quantum mechanical reflec...

Charge neutralization of an In-FEEP thruster was demonstrated with three different electron sources by zeroing the floating potential of the thruster and neutralizer system. The three cathodes used in the investigation include a mixed metal thermionic cathode, a carbon nanotube field emission cathode, and a Spindt-type Mo field emission array cathode. The field emission cathodes significantly i...