scholarly journals THE THERMAL FORM OF THE PHOTOEFFECT WITH THE DEBYE AND THE WIGNER CRYSTAL

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Miroslav Pardy ◽  
Keyword(s):  
Specific Heat ◽  
Work Function ◽  
Radiative Correction ◽  
Photoelectric Effect ◽  
Wigner Crystal ◽  
Photon Propagator ◽  
Crystal Medium

We define the photoelectric effect with the specific heat term replacing the work function. The photon propagator involving the radiative correction is also considered. We consider the Debye specific head for the 3D crystal medium, the specific heat for the 2D medium and specific heat for the Wigner crystal.

The free electron theory of metals

2018 ◽  
Author(s):  
L. Solymar ◽  
D. Walsh ◽  
R. R. A. Syms
Keyword(s):  
Distribution Function ◽  
Specific Heat ◽  
Work Function ◽  
Field Emission ◽  
Density Of States ◽  
Free Electron ◽  
Thermionic Emission ◽  
Photoelectric Effect ◽  
Electron Theory ◽  
Dirac Distribution

The model of the free electron theory is presented. The density of states and the Fermi–Dirac distribution function are discussed, leading to the specific heat of the electrons, the work function, thermionic emission, and the Schottky effects. As examples of applications the field-emission microscope and quartz–halogen lamps are discussed. The photoelectric effect and the energy diagrams relating to the junction between two metals are also discussed.

Conversion of UV and Visible Photons to Photoelectrons

2016 ◽  
pp. 1-8
Keyword(s):  
Work Function ◽  
Photoelectric Effect ◽  
Basic Knowledge ◽  
Great Success ◽  
Adsorbed Layers ◽  
Uv Photons

The operation of most of gaseous photomultipliers is based either on gas photoionization or on photoelectric effect from solid photocathodes. There have also been attempts to use liquid photocathodes which offer lower ionization thresholds compared to the corresponding vapors. A great success has been achieved with solid photocathodes covered with adsorbed layers of some photosensitive vapors which reduce the cathode work function and as a result extend the photosensitivity threshold towards long wavelengths. It also enhances their quantum efficiencies sometime on a factor of two. The main physic mechanisms of interactions of UV photons with gases as well as with liquid and solid photocathodes are described in detail in this chapter. This basic knowledge is important when designing and using gaseous photodetectors.

A Novel Method for True Work Function Determination of Metal Surfaces by Combined Kelvin Probe and Photoelectric Effect Measurements

2000 ◽  
Vol 619 ◽  
Author(s):  
Bert Lägel ◽  
Iain D. Baikie ◽  
Konrad Dirscherl ◽  
Uwe Petermann
Keyword(s):  
Thin Film ◽  
Work Function ◽  
Metal Surfaces ◽  
Surface Condition ◽  
High Vacuum ◽  
Photoelectric Effect ◽  
Ultra High Vacuum ◽  
Kelvin Probe ◽  
Novel Method

ABSTRACTWe have developed a novel method for in-situ measurements of the true work function (ø) of metal surfaces by combined ultra-high vacuum compatible Kelvin Probe and photoelectric effect measurements. The work function is an extremely sensitive parameter of surface condition and can be used to study oxidation and thin film growth on metal surfaces. For example, the increase in ø due to oxidation of polycrystalline rhenium is 1.9eV.The Kelvin Probe measures local work function differences between a conducting sample and a reference tip in a non-contact, truly non-invasive way over a wide temperature range. However, it is an inherently relative technique and does not provide an absolute work function if the work function of the tip (øtip) is unknown.We present a novel approach to measure øtip with the Kelvin Probe via the photoelectric effect, using a Gd foil as the photoelectron source, hereby combining the advantages of both methods to provide the absolute work function of the sample surface. We demonstrate the application of the technique by in-situ work function measurements during oxidation of polycrystalline rhenium. The extended Kelvin Probe method therefore has potential applications as a characterisation tool for thin film epitaxy and work function engineering of surfaces.

Excursus on the Carnot-Kelvin aspect of Thermodynamics

1937 ◽  
Vol 32 (5) ◽  
pp. 748-750
Keyword(s):  
Specific Heat ◽  
Work Function ◽  
Physical System ◽  
Thermal Capacity ◽  
General Function ◽  
Available Energy ◽  
Universal Space ◽  
Different Temperatures ◽  
Lower Temperature ◽  
Image Position

According to Carnot's postulate heat can give rise to work only by falling to lower temperature. This negation ensures that at each temperature a definite physical system possesses a work-function A, named by W. Thomson its available, energy at that temperature. This aspect of Carnot's postulate was enforced especially in Thomson and Tait's Nat. Phil. (1867). These available energies at different temperatures combine into one more general function, the isothermal available energy, which is a function of temperature θ as well as configuration. (Cf. the Minkowski condensation of personal spaces and times into a single universal space-time.) Thus we are entitled to assert the equationwhere Ψ1r is the force exerted by the coordinate ψr of configuration. The final term in δA though regular has not to do with ostensible work: and −η, as yet arbitrary, here equal to A/θ, may be described as the thermal capacity or specific heat of available energy.

A Novel Approach for True Work Function Determination of Electron-Emissive Materials by Combined Kelvin Probe and Photoelectric Effect Measurements

2000 ◽  
Vol 621 ◽  
Author(s):  
Bert Lägel ◽  
Iain D. Baikie ◽  
Konrad Dirscherl ◽  
Uwe Petermann
Keyword(s):  
Work Function ◽  
High Vacuum ◽  
Sample Surface ◽  
Photoelectric Effect ◽  
Ultra High Vacuum ◽  
Chemical Contamination ◽  
Kelvin Probe ◽  
Non Invasive ◽  
Novel Approach ◽  
The Stability

ABSTRACTFor the development of new electron-emissive materials knowledge of the work function Φ and changes in Φ is of particular interest. Among the various methods, the ultra-high vacuum (UHV) compatible scanning Kelvin Probe has been proven to be a superior technique to measure work function changes due to e.g. UHV cleaning processes, chemical contamination, thermal processing etc. with high accuracy (<1meV).The Kelvin Probe measures local work function differences between a conducting sample and a reference tip in a non-contact, truly non-invasive way over a wide temperature range. However, it is an inherently relative technique and does not provide an absolute work function if the work function of the tip (Φtip) is unknown.Here, we present a novel approach to measure Φtip with the Kelvin Probe via the photoelectric effect, where a Gd foil is used as the photoelectron source. This method thus provides the true work function of the sample surface with an accuracy of approx. 50meV. We demonstrate the application of the technique by in situ work function measurements on evaporated layers of the low work function material LaB6 on a Re substrate and follow the changes in Φ of LaB6 due to the surface adsorption of residual gas molecules. Thus, the extended Kelvin Probe method provides an excellent tool to characterise and monitor the stability of low work function surfaces.

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

Epitaxial ferroelectric thin films

1994 ◽  
Vol 52 ◽  
pp. 572-573
Author(s):  
S. G. Ghonge ◽  
E. Goo ◽  
R. Ramesh ◽  
R. Haakenaasen ◽  
D. K. Fork
Keyword(s):  
Single Crystal ◽  
Work Function ◽  
Nonvolatile Memory ◽  
Ferroelectric Properties ◽  
Electrical Contact ◽  
Memory Devices ◽  
Ferroelectric Films ◽  
Si Substrates ◽  
Electro Optic ◽  
Wide Range

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.

The Specific Heat of Steam

1882 ◽  
Vol 14 (342supp) ◽  
pp. 5451-5452
Author(s):  
J. MacFarlane Gray
Keyword(s):  
Specific Heat
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