Search results for "Coulomb"
showing 10 items of 379 documents
Tribology of Metal Cutting
2008
This chapter provides comprehensive knowledge regarding tribological behaviour of the cutting zone and characterizes specific features of the tool–chip contact that influence friction mechanisms in this area. Adhesion, plastic deformation of contacting asperities and ploughing action of the cutting edge are selected as three predominant mechanisms controlling sliding friction between the tool and the chip. The two-zone model of the tool–chip contact distinguishing seizure and sliding regions is characterized, along with experimental evidence based on photoelastic and material flow line techniques. Corresponding stress distributions for plane and restricted-contact cutting tools are provided…
Silicon Single Electron Transistors with Single and Multi Dot Characteristics
2000
AbstractSilicon single electron transistors (SET) with side gate have been fabricated on a heavily doped silicon-on-insulator (SOI) substrate. Samples demonstrate two types of characteristics: some of them demonstrate multiple dot behavior and one demonstrates single dot behavior in a wide temperature range. SETs demonstrate oscillations of drain-source current and changes in the width of the Coulomb blockade region with change of gate voltage at least up to 100 K. At temperature below 20 K long-term oscillations (relaxation) of source-drain current after switching the gate voltage has been observed in both multiple dot and single dot samples. Illumination affects both the characteristics o…
Single electron transistor fabricated on heavily doped silicon-on-insulator substrate
2001
Experiments on side-gated silicon single electron transistors (SET) fabricated on a heavily doped thin silicon-on-insulator substrate are reported. Some of the devices showed single-island-like and some multi-island-like behaviour, but the properties of individual samples changed with time. Single-electron gate modulation was observable up to T=100 K, at least. A slow response of SET current to a large change in gate voltage was observed, but the process speeded up under illumination.
Electron Binding in a Superatom with a Repulsive Coulomb Barrier: The Case of [Ag44(SC6H3F2)30]4– in the Gas Phase
2020
The electron binding mechanism in [Ag44(SC6H3F2)30]4- (SC6H3F2 = 3,4-difluorobenzenethiolate) tetra-anion was studied by photoelectron spectroscopy (PES), collision-induced dissociation mass spectrometry (CID-MS), and density functional theory (DFT) computations. PES showed that [Ag44(SC6H3F2)30]4- is energetically metastable with respect to electron autodetachment {[Ag44(SC6H3F2)30]3- + e-} and features a repulsive Coulomb barrier (RCB) with a height of 2.7 eV. However, CID-MS revealed that [Ag44(SC6H3F2)30]4- does not release an electron upon collisional excitation but undergoes dissociation. DFT computations performed on the known structure of [Ag44(SC6H3F2)30]4- confirmed the negative a…
Design and operation of CMOS-compatible electron pumps fabricated with optical lithography
2017
We report CMOS-compatible quantized current sources (electron pumps) fabricated with nanowires (NWs) on 300mm SOI wafers. Unlike other Al, GaAs or Si based metallic or semiconductor pumps, the fabrication does not rely on electron-beam lithography. The structure consists of two gates in series on the nanowire and the only difference with the SOI nanowire process lies in long (40nm) nitride spacers. As a result a single, silicide island gets isolated between the gates and transport is dominated by Coulomb blockade at cryogenic temperatures thanks to the small size and therefore capacitance of this island. Operation and performances comparable to devices fabricated using e-beam lithography is…
Noise and Microwave Properties of Set-Transistors
2002
Electron tunneling through a small tunnel junction with capacitance C 0 is suppressed by the so-called Coulomb blockade if the charging energy E c = e 2/2C∑ is larger than the thermal energy k B T 1. This effect is observed in a single electron tunneling transistor (SETT), which is a nano-meter size three-terminal device in which two leads connect to a small metallic island through two tunnel junctions. The excess charge on the island is regulated by the potential of the capacitively coupled gate electrode. The SETT is a very sensitive electrometer, noise levels of 10−5e/√Hz have been reached.2,3 A similar device, the electron pump, is made by connecting two or more islands in series throug…
Carbon Nanotube Radio-Frequency Single-Electron Transistor
2004
We discuss the theory of the radio-frequency single-electron transistor and the measurements that use multiwalled carbon nanotubes as active elements. Our devices made of plasma-enhanced chemical-vapor-deposition nanotubes yield charge sensitivities of 10-20 μe/ $$\sqrt {Hz}$$ . PACS numbers: 73.23.Hk, 73.63.Fg, 85.35.Gv, 85.35.Kt.
Do nuclei go pear-shaped? Coulomb excitation of 220Rn and 224Ra at REX-ISOLDE (CERN)
2014
Artículo escrito por muchos autores, sólo se referencian el primero, los autores que firman como Universidad Autónoma de Madrid y el grupo de colaboración en el caso de que aparezca en el artículo
Stick-slip and convergence of feedback-controlled systems with Coulomb friction
2020
An analysis of stick-slip behavior and convergence of trajectories in the feedback-controlled motion systems with discontinuous Coulomb friction is provided. A closed-form parameter-dependent stiction region, around an invariant equilibrium set, is proved to be always reachable and globally attractive. It is shown that only asymptotic convergence can be achieved, with at least one but mostly an infinite number of consecutive stick-slip cycles, independent of the initial conditions. Theoretical developments are supported by a number of numerical results with dedicated convergence examples.
Effects of confinement and external fields on structure and transport in colloidal dispersions in reduced dimensionality
2012
In this work, we focus on low-dimensional colloidal model systems, via simulation studies and also some complementary experiments, in order to elucidate the interplay between phase behavior, geometric structures and transport properties. In particular, we try to investigate the (nonlinear!) response of these very soft colloidal systems to various perturbations: uniform and uniaxial pressure, laser fields, shear due to moving boundaries and randomly quenched disorder.We study ordering phenomena on surfaces or in monolayers by Monte Carlo computer simulations of binary hard-disk mixtures, the influence of a substrate being modeled by an external potential. Weak external fields allow a control…