Applications of Liquid Metals in Nanotechnology

Abstract. The ionosphere is always assumed to contain equal numbers of positive and negative charges in a given volume (quasineutrality). Hence fewer electrons than positive charges are an indication of negative charges other than electrons. Theories predict and in-situ mass spectrometer measurements confirmed that these negative charges are negative ions, but recent experimental results suggest that other scavengers of free electrons can also be active in the mesosphere. Outside the polar summer mesosphere this additional removal of electrons is today believed to be due to meteoric dust, which maximises in the mesosphere. Data predominantly from the recent ECOMA flights are used to test this presumption. Six sounding rockets carried different dust detectors, as well as probes for electrons and ions. With such an instrumental ensemble one can assess whether indeed the existence of meteoric dust removes more electrons than would be expected from gas phase ion chemistry alone. Other factors potentially impacting on electron removal are also discussed in the paper.

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The Propagation of Radio Waves in an Ionised Atmosphere

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100009841 ◽

1931 ◽

Vol 27 (4) ◽

pp. 578-587 ◽

Cited By ~ 4

Author(s):

D. Burnett

Keyword(s):

Wave Length ◽

Upper Atmosphere ◽

Radio Waves ◽

Free Electrons ◽

Positive Ions ◽

Electrons And Ions ◽

Method Of Solution ◽

Velocity Of Propagation ◽

The Waves ◽

Electric Waves

Larmor has shown that if the upper atmosphere contains electrons (charge ε, mass m, density ν) and if collisions between these electrons and molecules—and also the forces between the electrons themselves—are negligible, then electric waves are propagated as if the dielectric constant of the medium were reduced by , from which it appears that, so long as the approximations are valid, the velocity of propagation of the waves can be increased indefinitely by increasing either the electron density or the wave-length λ. Several later authors have attempted to take account of the collisions between electrons and molecules, assuming free paths or velocities according to Maxwell's laws for a uniform gas, and it appears that the above law holds only for short waves; but it is doubtful how far the properties of a uniform gas can be assumed when periodic forces are acting. In the first part of this paper an alternative method of solution is given by means of Boltzmann's integral equation for a non-uniform gas, the analysis being similar to that used by Lorentz in discussing the motion of free electrons in a metal. Only the case when ν is small is considered, i.e. the interactions of electrons with one another and with positive ions are neglected. How far it is possible to increase the velocity of propagation by increasing ν is a more difficult question, but it seems possible that the forces between the electrons and ions may impose a limit just as collisions with neutral molecules limit the effect of increasing the wave-length.

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Review Lecture - Electrons in liquid metals and other disordered systems

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1970.0151 ◽

1970 ◽

Vol 318 (1535) ◽

pp. 401-420 ◽

Cited By ~ 16

Keyword(s):

Disordered Systems ◽

Liquid Metals ◽

Experimental Situation ◽

Impurity Band ◽

Electron Interaction ◽

Free Electrons ◽

Molecular Potentials ◽

Mechanical Interpretation ◽

Higher Order Corrections

In the past decade, a quantitative theory of the electrical properties of liquid metals has been built up, based upon a model of nearly free electrons scattered by the screened pseudopotentials of the assembly of ions. Within the uncertainties of our knowledge of the pseudopotentials, this simple theory agrees with the experimentally observed resistivity and thermoelectric power of non-transition metals and their alloys. It now seems that higher-order corrections to the n. f. e. formula in such systems are not large enough to be easily observed. Current interest is shifting to systems where the n. f. e. model should not be valid; liquid semiconductors, metallic vapours, metal-ammonia solutions, impurity band semiconductors, and semiconductivity glasses. The experimental situation is not reviewed, but attention is drawn to some basic theoretical questions, such as the nature of the atomic or molecular potentials, the role of electron-electron interaction, the character of the metal-insulator transition, and the quantum mechanical interpretation of such classical physical processes as the localization, percolation, and hopping of electrons in highly disordered materials.

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Precision Determination of Cyclotron Frequencies of Free Electrons and Ions

Lecture Notes in Chemistry - Ion Cyclotron Resonance Spectrometry II ◽

10.1007/978-3-642-50207-1_18 ◽

1982 ◽

pp. 318-325 ◽

Cited By ~ 1

Author(s):

G. Gräff

Keyword(s):

Free Electrons ◽

Precision Determination ◽

Electrons And Ions

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In situ irradiation effects studies in medium- and high-voltage TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137549 ◽

1995 ◽

Vol 53 ◽

pp. 234-235

Author(s):

Charles W. Allen

Keyword(s):

Cross Section ◽

Particle Flux ◽

Threshold Value ◽

High Energy ◽

Irradiation Damage ◽

Defect Complexes ◽

Lattice Position ◽

Electrons And Ions ◽

The Masses

With respect to structural consequences within a material, energetic electrons, above a threshold value of energy characteristic of a particular material, produce vacancy-interstial pairs (Frenkel pairs) by displacement of individual atoms, as illustrated for several materials in Table 1. Ion projectiles produce cascades of Frenkel pairs. Such displacement cascades result from high energy primary knock-on atoms which produce many secondary defects. These defects rearrange to form a variety of defect complexes on the time scale of tens of picoseconds following the primary displacement. A convenient measure of the extent of irradiation damage, both for electrons and ions, is the number of displacements per atom (dpa). 1 dpa means, on average, each atom in the irradiated region of material has been displaced once from its original lattice position. Displacement rate (dpa/s) is proportional to particle flux (cm-2s-1), the proportionality factor being the “displacement cross-section” σD (cm2). The cross-section σD depends mainly on the masses of target and projectile and on the kinetic energy of the projectile particle.

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Dynamic studies of silicide-mediated crystallization of amorphous silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131395 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1352-1353

Author(s):

C. Hayzelden ◽

J. L. Batstone

Keyword(s):

Ion Implantation ◽

Solid Phase ◽

Metallic Phase ◽

Single Crystal Substrate ◽

Free Electrons ◽

Melt Temperature ◽

Transmission Electron ◽

Crystal Substrate ◽

High Resolution Tem

Epitaxial reordering of amorphous Si(a-Si) on an underlying single-crystal substrate occurs well below the melt temperature by the process of solid phase epitaxial growth (SPEG). Growth of crystalline Si(c-Si) is known to be enhanced by the presence of small amounts of a metallic phase, presumably due to an interaction of the free electrons of the metal with the covalent Si bonds near the growing interface. Ion implantation of Ni was shown to lower the crystallization temperature of an a-Si thin film by approximately 200°C. Using in situ transmission electron microscopy (TEM), precipitates of NiSi2 formed within the a-Si film during annealing, were observed to migrate, leaving a trail of epitaxial c-Si. High resolution TEM revealed an epitaxial NiSi2/Si(l11) interface which was Type A. We discuss here the enhanced nucleation of c-Si and subsequent silicide-mediated SPEG of Ni-implanted a-Si.Thin films of a-Si, 950 Å thick, were deposited onto Si(100) wafers capped with 1000Å of a-SiO2. Ion implantation produced sharply peaked Ni concentrations of 4×l020 and 2×l021 ions cm−3, in the center of the films.

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The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117777 ◽

1985 ◽

Vol 43 ◽

pp. 154-157

Author(s):

A.J. Tousimis

Keyword(s):

Ion Beam ◽

Depth Resolution ◽

Sample Surface ◽

High Energy ◽

X Rays ◽

X Ray ◽

Electrons And Ions ◽

Spatial Depth ◽

Minimum Surface Area ◽

Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

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Detector strategies for environmental scanning electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131115 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1296-1297

Author(s):

Klaus-Ruediger Peters

Keyword(s):

High Vacuum ◽

Environmental Scanning Electron Microscopy ◽

Charge Carriers ◽

Environmental Scanning ◽

Surface Information ◽

X Ray ◽

Detector Electrode ◽

Electrons And Ions ◽

Low Energy Electrons ◽

Environmental Sem

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.

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