Showing papers on "Argon published in 1973"
TL;DR: In this paper, over 1200 Alnico magnets are used to contain a conventional discharge plasma produced by 1-20 A of emission from 6-48 small filaments at − 60 V.
Abstract: Over 1200 Alnico magnets (1.3 × 1.3 × 4 cm) are used to contain a conventional discharge plasma produced by 1–20 A of emission from 6–48 small filaments at − 60 V. Densities up to 1012 ions/cm3 are produced in argon at 2 × 10−3 Torr. At 5 × 10−6 Torr typical parameters are: 8 × 1010 ions/cm3; ni / n0 ≈ 0.7; Te ≈ 5 eV; Ti ≈ 0.5 eV; noise 〈 δn/n 〉 ≈ 2 × 10−4; and < 1% nonuniformity over a volume 31 cm diam by 69 cm. Uniform dense plasmas of He, D, and H are also produced. The ion containment appears to be both magnetic and electrostatic.
468 citations
TL;DR: The reaction rate constants for the quenching of electronic energy in metastable argon (3P0,2) by Kr, Xe, and a number of simple molecules have been measured as mentioned in this paper.
Abstract: Reaction rate constants for the quenching of electronic energy in metastable argon (3P0,2) by Kr, Xe, and a number of simple molecules have been measured A hollow, cold‐cathode discharge excites the metastables in a flow apparatus The concentration of metastables was followed by absorption spectroscopy as a function of time and of quenching molecule concentration Quenching of Ar*(3P2) by Kr, CO, N2, CF4, and H2(D2) proceeds at rates between 06 and 7 × 10−11 cm3 molecule −1 · sec−1 Except for Kr, Xe, N2, CO, and CH4, the 3P0 metastable level is quenched slightly more rapidly than the 3P2 level With the aid of data in the literature, the contribution from the product channels (Penning and associative ionization) are considered for quenching by NO and C2H2 These channels appear not to be of major importance for quenching since the ionization efficiency of these two reactions is low: ∼ 02 for NO and ∼ 01 for C2H2 The quenching mechanism is discussed in terms of both a curve crossing and a ``golden r
240 citations
232 citations
TL;DR: In this paper, the Ar L2,3MM Auger spectrum has been recorded and a great number of satellite lines are found many of which can be assigned to Auger transitions in doubly ionized argon.
Abstract: The Ar L2,3MM Auger spectrum has been recorded. A great number of satellite lines are found many of which can be assigned to Auger transitions in doubly ionized argon. Several shake-up satellites are also found in the spectrum. The relative intensities of the spectral lines are given and the intensities are compared with previous experiments and calculations.
131 citations
TL;DR: In this article, the authors measured the sum energy spectrum of electrons in argon and found a peak which is analyzed in terms of electron-electron correlations and showed that the peak is a peak in the energy spectrum.
Abstract: Momentum distributions have been measured separately for $3p$ and $3s$ electrons in argon. The measured summed energy spectrum shows the presence of a peak which is analyzed in terms of electron-electron correlations.
119 citations
TL;DR: In this paper, an electron diffraction study of extremely small clusters of argon atoms formed by homogeneous nucleation in an expansion nozzle system is presented, in which the clusters yielded good quality Debye-Scherrer patterns under conditions essentially free from all substrate interactions.
Abstract: We present an electron diffraction study of extremely small clusters of argon atoms formed by homogeneous nucleation in an expansion nozzle system. The clusters, in general comprising less than 1000 atoms, yielded good quality Debye‐Scherrer patterns under conditions essentially free from all substrate interactions. The high precision of the diffraction patterns, even at large angles, makes it possible to assign an effective fcc structure to the particles. However, an anomalously large 111 peak is observed consistently and may be interpreted as resulting from vestiges of noncrystalline structure exhibited by the aggregates in the early stages of their growth.
118 citations
TL;DR: In this paper, the rate constants for the deexcitation of Ar(3P2) metastable atoms by many gases were measured, and the corresponding cross sections were calculated, and they appeared to be a function of the long range forces and thus it can be presented as a function for polarizability.
Abstract: The rate constants for the de‐excitation of Ar(3P2) metastable atoms by many gases were measured, and the corresponding cross sections are calculated. These rate constants were measured in a static system using the N2(C 2Πu→ B 3Πg) emission band at 3371 A to detect the Ar(3P2). The results are compared with those obtained for the quenching of He(2 3S) metastable atoms and for photoabsorption at the argon resonance wavelengths. From these comparisons the de‐excitation cross section of metastable atoms appears to be a function of the long range forces and thus it can be presented as a function of the polarizability.
115 citations
TL;DR: In this article, the influence of collisional-induced absorption on the oscillator output is indicated by the measurement of a blue shift in the spectrum of the stimulated output relative to the case of pure xenon.
Abstract: Experimental data demonstrating coherent oscillation in high‐pressure krypton at 1457 ± 1 A with an 8‐A linewidth are reported. Observations of stimulated emission from argon/xenon mixtures arising from the operation of efficient energy transfer processes and resulting in a twofold enhancement of the xenon laser output at ∼ 1720 A are also given. The influence of collisional‐induced absorption on the oscillator output is indicated by the measurement of a blue shift in the spectrum of the stimulated output for argon/xenon mixtures relative to the case of pure xenon.
112 citations
TL;DR: In this article, a photolysis of hydrogen and deuterium-containing compounds in an argon matrix correspond well with similar absorptions reported in studies of the trapped products of a glow discharge through Ar:H 2 and Ar:D 2 mixtures.
109 citations
TL;DR: In this paper, heat transfer measurements for film condensation of steam on a vertical plane surface in the presence of air, argon, neon and helium, under free-convection conditions are reported.
108 citations
TL;DR: In this paper, the influence of the sputtering ion energy (5 to 50 keV argon) on the original range distribution has been investigated with a standard implantation profile as a reference (20 keV boron in amorphous silicon).
Abstract: Using a recently developed high sensitivity secondary ion mass spectrometer the influence of the sputtering ion energy (5 to 50 keV argon) on the original range distribution has been investigated with a standard implantation profile as a reference (20 keV boron in amorphous silicon). It was found that recoil processes change the distribution only in the long range tail so that projected range and standard deviation are not influenced by this effect within the limits of experimental accuracy. Because of the low sputtering yield of silicon (S ≃ 2 atoms/ion), however, there is a change in sputtering rate at the beginning of layer removal until equilibrium between implantation and release of argon is obtained. This effect results in an increase in the measured value of the projected range which can be corrected by extrapolation to zero sputtering energy (Rp = 690 A, ΔRp =280 A). Neither scanning electron microscopy nor talysurf measurements showed any indication for the development of a surface topog...
TL;DR: The 15°K deposition of alkali metal atoms and ozone molecules at high dilution in argon produced very intense bands near 800 cm−1 and weak bands near 600 cm− 1 which showed appropriate oxygen isotopic shifts for assignment to v3 and v2 of the ozonide ion as mentioned in this paper.
Abstract: The 15°K deposition of alkali metal atoms and ozone molecules at high dilution in argon produced very intense bands near 800 cm−1 and weak bands near 600 cm−1 which showed appropriate oxygen isotopic shifts for assignment to v3 and v2 of the ozonide ion. Energetic considerations and alkali metal effects clearly indicated bonding of the metal cation to the ozonide anion. The use of scrambled isotopic ozones showed that the metal cation was symmetrically bound to the ozonide anion in a C2v structure; the symmetric interionic stretching mode was observed at 281 cm−1 for Cs+O3−. The cesium‐ozone reaction produced argon matrix fundamentals for CsO at 322 cm−1 and Cs2O at 457 cm−1; simultaneous mercury arc photolysis was required to yield the LiO absorption at 752 cm−1 from the lithium‐ozone argon matrix reaction.
TL;DR: The neutral-atmosphere composition experiment instrumentation is designed to obtain in-situ measurements of neutral thermosphere compositions from Atmosphere Explorer-C, -D, and -E.
Abstract: The neutral-atmosphere composition experiment instrumentation is designed to obtain in-situ measurements of neutral thermosphere composition from Atmosphere Explorer-C, -D, and -E. The system is based on previously flown OGO-6 and San Marco-3 composition instruments. The mass-spectrometer sensor includes a gold-plated thermalizing chamber and ion source, a hyperbolic rod quadrupole analyzer, and an off-axis electron multiplier. Automatic ion-source sensitivity control and pulse-counting techniques provide density measurement capability from approximately 125 to 1000 km altitude. The normal operating mode includes measurement at all masses in the range of 1 to 44 amu, with emphasis on hydrogen, helium, oxygen, nitrogen, and argon.
TL;DR: The coefficient of shear viscosity of fluid argon has been measured at temperatures from 85 to 298 K and at pressures up to 34 MN/m2 using the torsional crystal viscometer as discussed by the authors.
TL;DR: In this paper, it was shown that sputtering yield of various materials submitted to argon ion (1 ke V) bombardment decreases strongly with increase of oxygen pressure in the atmosphere of the sputtering chamber.
Abstract: It is shown that the sputtering yield of various materials submitted to argon ion (1 ke V) bombardment decreases strongly with increase of oxygen pressure in the atmosphere of the sputtering chamber. The sputtering yields are plotted against the “poisoning ratio” (the poisoning ratio is defined as the ratio of the rate of arrival of oxygen molecules at the target surface to that of the rate of removal of sputtered atoms). On the curves representing the sputtering yield versus the poisoning ratio, two particular values are pointed out for each material. Between these two values the sputtering yield decreases as the poisoning ratio increases, out of these values the sputtering yield is quite independent of the poisoning ratio.
01 Jan 1973
TL;DR: The Apollo 17 mass spectrometer has confirmed the existence of helium, neon, argon, and possibly molecular hydrogen in the lunar atmosphere Helium and neon concentrations are in agreement with model predictions based on the solar wind as a source and their being non-condensable gases Ar-40 and Ar-36 both exhibit a predawn enhancement which indicates that they are condensable gases on the night side and are re-released into the atmosphere at the sunrise terminator as mentioned in this paper.
Abstract: The Apollo 17 mass spectrometer has confirmed the existence of helium, neon, argon, and possibly molecular hydrogen in the lunar atmosphere Helium and neon concentrations are in agreement with model predictions based on the solar wind as a source and their being noncondensable gases Ar-40 and Ar-36 both exhibit a predawn enhancement which indicates that they are condensable gases on the nightside and are re-released into the atmosphere at the sunrise terminator Hydrogen probably exists in the lunar atmosphere in the molecular rather than atomic state, having been released from the surface in the molecular form Total nighttime gas concentration of known species in the lunar atmosphere is 200,000 molecules/cu cm
TL;DR: In this article, nonequilibrium molecular dynamic simulation of liquid argon yields the strain-rate dependence of shear viscosity, which is consistent with the equilibrium Green-Kubo viscosities calculated by Levesque, Verlet, and Kurkijarvi.
Abstract: Nonequilibrium molecular dynamic simulation of liquid argon yields the strain-rate dependence of shear viscosity. Near the triple point the apparent viscosity decreases with increasing strain rate; the extrapolated zero-gradient viscosity is consistent with the equilibrium Green-Kubo viscosity calculated by Levesque, Verlet, and Kurkijarvi. At higher temperatures along the saturated vapor pressure line, our results are insensitive to the strain rate and agree well with experimental data for liquid argon.
TL;DR: The scattering of hydrogen, deuterium, and rare gases from the (111) face of silver has been studied at ultrahigh vacuum as mentioned in this paper, where the surfaces were prepared by argon ion bombardment and high temperature annealing incident angles between 20° and 65° and surface temperatures between room temperature and 573°K.
TL;DR: In this paper, the C2 to C4 alkenes were isolated in argon matrices at 20 K. The relative intensities in the matrix were in agreement with the small energy difference reported from microwave spectroscopy.
Abstract: Infra-red spectra are reported of the C2 to C4 alkenes isolated in argon matrices at 20 K. Absorptions due to both conformers of but-1-ene were observed, and a complete assignment is given. The relative intensities in the matrix are in agreement with the small energy difference reported from microwave spectroscopy. An assignment of the fundamental modes is presented for each alkene.
TL;DR: In this article, the i.r. spectra of H 2 CO and D 2 CO in solid argon and in solid nitrogen and the Raman spectra were reported as functions of temperature and matrix concentration.
TL;DR: Theoretical K-shell Auger groups rates and fluorescence yields for 47 defect electronic configurations of argon are presented in this article, and energy shifts from the normal x rays and the Auger- electron energies are also given for these defect configurations.
Abstract: Theoretical K-shell Auger groups rates. K alpha and K BETA x-ray rates. and fluorescence yields are presented for 47 defect electronic configurations of argon. Energy shifts from the normal x rays and the Auger- electron energies are also given for these defect configurations. These theoretical results can be conveniently used in the analysis of experiments involving heavy-ion-argon collisions. (auth)
TL;DR: In this paper, a radiative recombination model for rare gas plasmas has been proposed, based on which the parameters of analytical importance are the concentration and energy of electrons in a high energy electron group, the concentration of metastable rare gas atoms and the ionization potential of the plasma gas.
TL;DR: In this paper, a tilted copper wedge at 16°K was examined by argon and krypton plasma laser excitation and the vibrational analysis for six isotopic ozonide species produced the oxygen−oxygen force constant 4.18 ± 0.11 mdyn/A.
Abstract: Beams of alkali metal atoms and ozone molecules at high dilution in argon were condensed on a tilted copper wedge at 16°K and were examined by argon and krypton plasma laser excitation. Very intense bands shifted 1010 cm−1 below the exciting lines showed small alkali metal effects and appropriate oxygen‐18 shifts for assignment to the v1 symmetric oxygen‐oxygen mode of the ozonide ion in the M+O3− species. The intense fundamental and a regular progression of overtones out to 4v1 suggest that these spectra are probably due to the resonance Raman effect. Vibrational analysis for six isotopic ozonide species produced the oxygen‐oxygen force constant 4.18 ± 0.11 mdyn/A. The spectroscopic value for the heat of atomization of the ozonide ion calculated from the vibrational constants ω1 = 1028.2 cm−1 and X11 = 4.95 cm−1 for Cs+O3− is 153 kcal/mole, which agrees well with the thermodynamic value.
TL;DR: In this article, the maximum possible influence of radial convection is calculated by assuming that convective flow maintains a uniform pressure in space and time, and curves are given showing the contributions of thermal conduction, convection, and radiation to the decay of electrical conductance.
Abstract: Calculations assuming thermal equilibrium have been made of properties of cylindrical arc plasmas which decay after the removal of the electric field. Account is taken of energy losses due to thermal conduction and radiation, self‐absorption effects being included where possible in the treatment of radiation. The maximum possible influence of radial convection is calculated by assuming that convective flow maintains a uniform pressure in space and time. Comparisons are made of the calculated decay of electrical conductance with experimental measurements, where available, for A, N2, SF6, H2, and air; curves are given showing the contributions of thermal conduction, convection, and radiation to the decay. The theoretical results underestimate the rapid decays of electrical conductance that have been observed for plasma temperatures of less than 10 000 °K in air, and less than 7000 °K in SF6, but good agreement between theory and experiment is obtained for argon. Information from rate coefficients supports the view that the rate of atomic recombination to form molecules is insufficient to maintain thermal equilibrium and as a result there is an enhanced rate of cooling. Theoretical transient temperature profiles in air are also compared with published experimental profiles.
TL;DR: In this article, the authors presented results from thermal-release argon 40-argon 39 dating experiments on four calcium-rich achondrites, including Pasamonte, St. Petersburg, Lafayette and Stannern.
TL;DR: A seagoing gas chromatographic system for the rapid and precise determination of dissolved gases in sea water is described in this article, where separate instruments are employed for total inorganic carbon, and for nitrogen, oxygen, and argon analyses.
TL;DR: In this paper, the thermal conductivities of neon, argon, and xenon were measured at 760 mm Hg in the ranges 1000-1500 °K (neon, xenon) and 1000-2500°K (argon) and the data were correlated by expressions of the form λ = a Tb, where a and b are constants depending upon the gas.
Abstract: Thermal conductivities λ of neon, argon, and xenon were measured at 760 mm Hg in the ranges 1000–1500 °K (neon, xenon) and 1000–2500 °K (argon). The data were correlated by expressions of the form λ = a Tb, where a and b are constants depending upon the gas. The results were compared with (1) existing data, (2) viscosity measurements η, by means of the coefficient f = λ/(2.5ηCv), and (3) values calculated from an extended law of corresponding states. The correlations obtained from the measurements were found to describe well the thermal conductivities of all three gases not only within the temperature ranges of the experiments but also over the range 900–2500 °K.
TL;DR: In this paper, an electrostatic probe is used to measure the currentvoltage of a high-current (100 A), high-pressure (1 bar), DC argon (TIG) welding arc.
Abstract: The electrostatic probe is an attractive diagnostic tool for DC welding arcs. The current-voltage characteristic of such a probe in a high-current (100 A), high-pressure (1 bar), DC argon (TIG) welding arc is found to give a very flat ion saturation region. Sheath thicknesses are estimated to be much smaller than 1 ?m, ie less than the mean free path, so that conventional collisionless probe theory should be applicable - in contrast to the flame plasmas dealt with by Thomas (1969) and others. By using an Abel inversion technique the measured probe current can be converted to a radial distribution of current. The temperature variation across the arc can then be derived from this current variation. By measuring the radial temperature profile at several points along the length of the arc column, a complete isothermal map of the TIG arc has been obtained which is important for basic calculations of energy transfer.
TL;DR: In this article, it was shown that the possibility of argon loss from open potassium sites, such as on crystal surfaces and from expanded layers, was investigated by acid dissolution techniques, and it appeared that the presence of potassium in sites where argon is readily lost, although such factors as late epigenetic gain of potassium by glauconite may also contribute to their low radiometric ages.