Electron Work Function Of Metals Research Articles

Two-extremum electrostatic potential of metal-lattice plasma and the work function of an electron

Abstract Metal-lattice plasma is treated as a neutral two-component two-phase system of 2D surface and 3D bulk. Free electron density and bulk chemical potential are used as intensive parameters of the system with the phase boundary position determined in the crystalline lattice. A semiempirical expression for the electron screened electrostatic potential is constructed using the lattice-plasma polarization concept. It comprises an image term and three repulsion/attraction terms of second and fourth orders. The novel curve has two extremes and agrees with certain theoretical forms of potential. A practical formula for the electron work function of metals and a simplified schema of electronic structure at the metal/vacuum interface are proposed. This yields 10.44 eV for the Fermi energy of free electron gas; -5.817 eV for the Fermi energy level; 4.509 eV for the average work function of bcc tungsten. Selected data are also given for fcc Cu and hcp Re. For harmonic frequencies ~ 10E16 per s of the self-excited metal-lattice plasma, energy gaps of 14.54 and 8.02 eV are found, which correspond to the bulk and surface plasmons, respectively. Further extension of this thermodynamics and metal-lattice theory based approach may contribute to a better understanding of theoretical models which are employed in chemical physics, catalysis and materials science of nanostructures.

Correlation between the electron work function of metals and their bulk moduli, thermal expansion and heat capacity via the Lennard-Jones potential

Properties of metallic materials are intrinsically determined by their electron behaviour. However, relevant theoretical treatment involving quantum mechanics is complicated and difficult to be applied in materials design. In this article, a simple and general approach is proposed to correlate properties of metals with their electron work function using the Lennard–Jones potential as a bridge. The approach is applied to several properties of metallic materials, including bulk modulus, thermal expansion and heat capacity (Debye temperature). The established correlations are consistent with reported experimental results, verifying the dependence of the properties on electron work function. This new methodology may help generate complementary clues for advanced material design, element selection and modification of bulk materials or phases on a feasible electronic base.

Surfaces and Interfaces in Electrochemistry: 2003 Frumkin Memorial Medal Award Lecture

This Award Lecture, delivered on the occasion of the presentation of the 2003 Frumkin Memorial Medal to the Author, consists of three parts: A brief introduction, a memorial section where the events in which Professor Frumkin and the author were jointly involved, and a scientific section where the main concepts at the basis of the scientific contacts between Frumkin and the author are illustrated. Among the latter, emphasis is placed on the relationship between the potential of zero charge and the electron work function of metals.

Influences of tensile strain and strain rate on the electron work function of metals and alloys

Abstract The effect of deformation on the electronic work function (EWF) has been well documented and the dislocation mechanism responsible for the change in the EWF due to deformation has been postulated. This letter reports our recent experimental investigations on the change in the EWF of tensile specimens using a scanning Kelvin probe. It was demonstrated that both strain and strain rate can decrease the EWF, which is consistent with the previous experimental observations using different deformation conditions and which basically supports the postulation.

Effects of elastic and plastic deformations on the electron work function of metals during bending tests

The high sensitivity of the electron work function (EWF) to surface conditions has attracted increasing interest in the application of the electron work function (EWF) to investigate tribological phenomena using the Kelvin probing technique. In this study, the correlation between the EWF and both the elastic and plastic deformation of copper and aluminium during bending tests was investigated. It was demonstrated that, in the elastic range, tensile strain decreased the EWF, while compressive strain increased the EWF. However, in the plastic range, the EWF always decreased with plastic deformation irrespectively of whether it was tensile or compressive. The mechanism responsible for the variation in EWF with elastic and plastic deformation is analysed and discussed.

Polar and protective properties of esters

1. A number of esters used as aviation oils and hydraulic fluids have been investigated with respect to polar and electron donor-acceptor properties at an interface with metal. It has been shown that the majority of the esters are high in dielectric permeability and that they decrease the electron work function of metals, being electron donors and being sorbed at the > CO = group. 2. The least polar of the esters is the pentaerythritol ester of C5–C9 acids, which increases the electron work function. The sorption of esters on metal is in the nature of a physical adsorption. Satisfactory protective properties and the capability for rapid removal of an electrolyte from a metal surface are provided by the esters of mmethylcyclohexanol, adipic acid, and 2-ethylhexanol (No. 7), the monodecyl ester of diphenic acid (No. 8), and the didecyl ester of benzylsuccinic acid (No. 9). 3. Esters can be utilized as components of combination corrosion inhibitors, but all of the esters that were investigated are inferior in this respect to fatty acids.

Negative Work Function of Thermal Positrons in Metals

Theoretical study shows that thermalized positrons are thrown out of a metal with an energy of the order of several eV. This phenomenon is shown to be closely related to the electron work function of metals. Since energy is emitted when positrons leave the metal surface, it is named "negative work function." The negative work function of thermal positrons is ${\ensuremath{\Phi}}^{p}\ensuremath{\simeq}\ensuremath{\Delta}{\ensuremath{\varphi}}^{e}\ensuremath{-}{\ensuremath{\mu}}_{c}^{p}+O(\frac{{N}_{p}}{N})$, where ${N}_{p}$ and $N$ are the total number of positrons and electrons, respectively, in the metal. $\ensuremath{\Delta}{\ensuremath{\varphi}}^{e}$ is the electrostatic potential across the metal surface due to the double layer taken from the electron work-function calculation, and ${\ensuremath{\mu}}_{c}^{p}$ is the correlation contribution to the positron chemical potential at the mean electrostatic potential.

Determination of Planck's constant and electron work function of metal by the charge storage method

Determination of Planck's constant and electron work function of metal by the charge storage method

Theoretical study of zero-field electron work function of metal immersed in gas-direct application to cesium thermionic diode : Luke, Keung P., and John R. Smith, Lewis Research Center, NASA Technical Note, NASA TN D-2357, July 1964, 66 pp.

Theoretical study of zero-field electron work function of metal immersed in gas-direct application to cesium thermionic diode : Luke, Keung P., and John R. Smith, Lewis Research Center, NASA Technical Note, NASA TN D-2357, July 1964, 66 pp.