Showing papers on "Ionization published in 1971"
TL;DR: In this article, the authors investigated the electrical conduction process in amorphous solids, using as a basis the ionization of local defects by an applied field, and showed that the Poole-Frenkel effect is a limiting case of a more general analysis that can be extended to cover the experimentally available range of field stress and temperature.
Abstract: The nature of the electrical conduction process in amorphous solids, using as a basis the ionization of local defects by an applied field, is investigated. It is shown that the Poole-Frenkel effect is a limiting case of a more general analysis that can be extended to cover the experimentally available range of field stress and temperature. At low temperature conduction is by tunnelling emission out of the defects into the quasi-conduction band of the host material whereas at high temperatures thermal emission becomes dominant. Between the two regions a thermal-field emission process has been identified with the characteristic of ln J ∝ T −⅓.
560 citations
TL;DR: In this article, the radiative cooling coefficient for a low-density optically thin plasma with no molecules or dust, of cosmic abundances in the range from 10,000 to 100,000,000 K, was derived.
Abstract: The paper extends and improves the radiative cooling coefficient calculations of Cox and Tucker (1969) and Cox and Daltabuit (1971) for a low-density optically thin plasma with no molecules or dust, of cosmic abundances in the range from 10,000 to 100,000,000 K. Earlier rates applied to a plasma containing H, He, C, N, O, Ne, Mg, Si, and S; the present study added Ca, Fe, and Ni. For the elements included, many individual lines are calculated which previously has been averaged together. The cooling processes considered are permitted, forbidden, and semiforbidden line transitions, including contributions from dielectronic recombination and bremsstrahlung, radiative recombination, and two-photon continua. The ionization balance is calculated in collisional equilibrium using an approximate auto-ionization following inner-shell excitation and the low-density limit for the dielectronic recombination rate. Cooling in various observational bands in the soft X-ray region is determined.
524 citations
479 citations
TL;DR: In this paper, a double focusing electrostatic electron spectrometer has been used to measure the K-LL Auger spectra resulting from electron impact for each of the elements in the gaseous molecules N2, O2, CO, NO, H2O, and CO2.
Abstract: A double‐focusing electrostatic electron spectrometer has been used to measure the K—LL Auger spectra resulting from electron impact for each of the elements in the gaseous molecules N2, O2, CO, NO, H2O, and CO2. An energy resolution of 0.09% full width half‐maximum was normally employed. A method for analyzing these complex spectra is described. It involves the identification of normal and satellite lines. The former are defined as arising from single electron ionization from the K shell without additional excitation followed by an Auger process in which one electron fills the vacancy while a second goes into the continuum, and where all the other electrons remain in their same orbitals. Satellite lines result when extra excitation occurs either in the initial formation of the K vacancy or in the subsequent Auger process. To aid in the identification of these satellite lines, auxiliary experiments have been performed such as the study of discrete energy losses in photoionization due to electron shake‐up,...
460 citations
TL;DR: In this article, the authors measured the energy distribution and angular dependence of secondary electrons generated by the impact of 100−2000eV electrons on He, N2, and O2 and measured the shape of the spectra of all the gases, except Ar, Kr, and Xe.
Abstract: The energy distribution and angular dependence of secondary electrons generated by the impact of 100–2000‐eV electrons on He, N2, and O2 and by the impact of 500‐eV electrons on Ne, Ar, Kr, Xe, H2, NO, CO, H2O, NH3, CH4, C2H2, and CO2 have been measured over the 4–200‐eV range. The measurements were made in a crossed‐beam apparatus with the use of a fixed hemispherical electrostatic analyzer and a rotatable electron gun. The observed spectra were integrated over angle to obtain relative cross sections for secondary‐electron production. It was found that the shapes of the spectra of all the gases (except Ar, Kr, and Xe, which contain intense electron emission features in this energy range) were smooth and qualitatively similar, approaching a constant cross section at low secondary energies, and falling off at high secondary energies slightly faster than Es−2, where E8 was the energy of the secondary. The shape of the spectrum was found to be nearly independent of primary energy in He, O2, and N2.
356 citations
236 citations
TL;DR: In this paper, the Schrodinger equation for two electrons in a Coulomb field is studied in the critical region where both electrons have near-zero kinetic energies, and the main feature of this problem is that the mutual screening between the two electrons determines and is determined by the partition of the available energy between them.
Abstract: The Schr\"odinger equation for two electrons in a Coulomb field is studied in the critical region where both electrons have near-zero kinetic energies. The main feature of this problem is that the mutual screening between the two electrons determines and is determined by the partition of the available energy between them. This energy-dependent screening can be taken into account to yield a complex potential in the radial variable $R={({r}_{1}^{2}+{r}_{2}^{2})}^{\frac{1}{2}}$ of the six-dimensional configuration space of the two electrons. Solutions of this equation are obtained and are shown to correspond to the classical orbits given in an early paper by Wannier. A possible way is indicated of using these wave functions to establish the Wannier threshold law which, for ionization of neutral atoms, is $\ensuremath{\sigma}\ensuremath{\propto}{E}^{1.127}$. Finally, the interplay between the total energy and the Coulomb potential is discussed both for this problem and for the case of one electron in the field of a nucleus.
223 citations
TL;DR: In this paper, the energy of the gaseous ions of the lanthanides and actinides was estimated for the lowest spectroscopic level of the configurations involving 4f, 5d, 6p, and 6s electrons for lanthanide ions and 5f, 6d, 7p and 7s electron for actinide ions.
Abstract: Methods are described for estimating energies of the electronic configurations of the gaseous ions of the lanthanides and actinides. Energies are tabulated for the lowest spectroscopic level of the configurations involving 4f, 5d, 6p, and 6s electrons for the lanthanide ions and 5f, 6d, 7p, and 7s electrons for the actinide ions. Some additional values are listed to be added to the previous tabulation for neutral atoms.
184 citations
TL;DR: In this article, the Hamilton-Jacobi equation and the continuity equation for electron-atom ionization problem at zero total angular momentum are investigated in the neighbourhood of saddle points of the potential.
Abstract: The solutions of the Hamilton-Jacobi equation and of the continuity equation for electron-atom ionization problem at zero total angular momentum are investigated in the neighbourhood of saddle points of the potential. Solutions are found which describe sets of orbits whose points of condensation coincide with the saddle points of the potential. The asymptotic behaviour of solutions corresponds to a spherically outgoing wave or to a plane wave. The energy dependence of WKB wave functions is determined and by means of a matching procedure the Wannier ionization threshold law has been confirmed. The connection between the WKB approximation and the asymptotic expansion of the zero- energy wave function has been considered.
TL;DR: In this article, the experimental cross-sections for the important collision processes are reviewed and analytic expressions are formed which describe the data reasonably well, with the analytical expressions for the cross-section used to calculate rate coefficients.
Abstract: The depth of penetration of fast hydrogen atoms into a fusion reactor plasma, before they become ionized and held by the magnetic field, is of importance in connection with the heating and refuelling of such a plasma. Here the experimental cross-sections for the important collision processes are reviewed and analytic expressions are formed which describe the data reasonably well.The ion and electron energy distributions to be expected in both toroidal and mirror reactors are used, with the analytic expressions for the cross-sections, to calculate rate coefficients. The plasma thickness T for an 1/e reduction in intensity of the atom beam is then obtained as a function of beam energy and plasma temperature over the range 0.1 to 2000 keV (D+, Do). As an example a 1 MeV deuterium atom beam entering a toroidal reactor plasma has T=1.7×1016 and 2.5×1016cm−2 for plasma temperatures of 1 and 100 keV, respectively.
TL;DR: In this paper, analytical expressions for treating the threshold regions of photoionization efficiency curves are derived for dissociative ionization of small molecules such as F2 and HCN, and some general observations applicable to the diatomic halogens, hydrogen halides, and alkali halides.
Abstract: Analytical expressions are derived for treating the threshold regions of photoionization efficiency curves The effects of slitwidth, the initial thermal energy of the molecular system, and Franck–Condon factors are considered In the dissociative ionization of small molecules such as F2 and HCN, discrepancies can arise from failure to take these factors into account It is also shown that for large polyatomic molecules, the use of a Watanabe‐type plot to determine the adiabatic ionization potential can lead to large errors The paper concludes with detailed applications to HF, O2, S2, Se2, Te2, S6, and S8, and some general observations applicable to the diatomic halogens, hydrogen halides, and alkali halides
TL;DR: In this article, the first and second ionization constants for H2S and strongly alkaline sulphide solutions were evaluated up to 270° of aqueous H2s solutions and up to 350° of H2SO4 solutions.
TL;DR: In this paper, the positive ions incident on the substrate plane in a planar diode discharge system were observed with an electrostatic deflection energy analyzer and a quadrupole mass spectrometer.
Abstract: The positive ions incident on the substrate plane in a planar diode discharge system are observed with an electrostatic deflection energy analyzer and a quadrupole mass spectrometer. Several targets have been rf sputtered in rare‐gas discharges and the mass spectra that are obtained indicate that the sputtered species, which leave the target predominantly as neutrals, are subsequently ionized in the discharge by Penning ionization rather than by electron‐impact ionization or other ion‐molecule reactions.
TL;DR: In this paper, the authors have calculated discrete and continuum generalized oscillator strengths for all the occupied shells of He-Na and the $3s$ and $3p$ continuum GAs for Ar with a one-electron common-central-potential unrelaxed-core approximation.
Abstract: We have calculated discrete and continuum generalized oscillator strengths for all the occupied shells of He-Na and the $3s$ and $3p$ continuum generalized oscillator strengths for Ar. The calculations are done with a one-electron common-central-potential unrelaxed-core approximation. The generalized oscillator strengths were used to compute proton-excitation and -ionization cross sections and stopping power, electron-ionization cross sections, and neutral-neutral-ionization and -stripping cross sections. For proton ionization above 200 keV and electron ionization above 200 eV, the calculated cross sections are in better than 20% agreement with experiment. The calculated proton stopping power is lower than experiment by 25% at 100 keV and within 10% at 1 MeV. The computed He-He ionization cross section agrees with the measurement by Wittkower, Levy, and Gilbody, while the computed He-Ar ionization cross section is a factor of 5 higher than the measurement by Puckett, Taylor, and Martin.
TL;DR: In this paper, the ultraviolet spectrum of furan has been measured as a function of energy and the protection spectrum up to ionization potentials of 25 eV. This formation, together with quantum-chemical calculations, allows a description of the electronic structure of the furan to be given.
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01 Jan 1971
TL;DR: In this paper, a short introduction to the physics of Aurora is given, along with a detailed analysis of the spectral properties of the local auroral display and its properties in the atmosphere.
Abstract: 1 The Occurrence and Cause of Auroras: a Short Introduction.- 1.1 Local Auroral Forms.- 1.1.1 Geometry.- 1.1.2 Intensity.- 1.1.3 The Local Auroral Display.- 1.2 Auroral Morphology.- 1.2.1 Magnetic Guiding of Auroral Particles Coordinate Systems.- 1.2.2 Worldwide Auroral Morphology.- 1.2.3 Mid-Latitude Red Arcs.- 1.2.4 Polar Glow and Mantle Auroras.- 1.3 Particle Behaviour: Reflection, Absorption and Scattering.- 1.3.1 Mirror Effects.- 1.3.2 Absorption and Scattering of Particles in the Atmosphere.- References.- 2 The Electron Aurora: Main Characteristics and Luminosity.- 2.1 Introduction.- 2.2 N2+ Emission and Ionization.- 2.3 Theoretical Height Distribution of the First Negative N2+ Bands.- 2.4 Height Distribution of Other Emissions.- 2.5 Electron Energies Inferred from Height Distribution of Auroral Luminosity.- 2.6 Geometry and Motion of the Electron Aurora.- 2.7 Latitude Variations in Auroral Heights.- References.- 3 The Proton Aurora.- 3.1 Introduction.- 3.2 Theory of Hydrogen Line Emission.- 3.2.1 Auroral Protons, the Solar Wind and the Magnetosphere.- 3.2.2 The Proton Beam in the Atmosphere: Charge Exchange.- 3.2.3 The Proton Beam in the Atmosphere Diffusion.- 3.2.4 Excitation of the Hydrogen Lines.- 3.2.5 The Relation Between Hydrogen Lines and the First Negative N2+ Bands.- 3.2.6 The Hydrogen Line Profiles.- 3.2.7 Height Distribution of the Hydrogen Emissions.- 3.3 Observations on Hydrogen Lines.- 3.3.1 Techniques.- 3.3.2 The Intensity Ratio Between the Hydrogen Lines and the First Negative N2+ Bands.- 3.3.3 Absolute Intensities and Balmer Decrement.- 3.3.4 Geometry of Proton Aurora.- 3.3.5 Morphology of Proton Aurora.- 3.3.6 The Doppler Profiles.- References.- 4 The Optical Spectrum of Aurora.- 4.1 Description.- 4.1.1 Introduction.- 4.1.2 The Auroral Spectrum.- 4.1.3 Forbidden Atomic Emissions.- 4.1.4 Permitted Atomic Emissions.- 4.1.5 Molecular Emissions.- 4.1.6 The Intensity Distribution in the Spectrum.- 4.2 Local Variations in the Spectrum.- 4.2.1 Introduction.- 4.2.2 The I(5577)/I(1 neg)Ratio.- 4.2.3 Other Forbidden Emissions.- 4.2.4 Permitted Atomic Lines.- 4.2.5 Permitted Molecular Bands.- 4.3 Latitudinal and Zonal Variations.- References.- 5 Physics of the Optical Emissions.- 5.1 Excitation.- 5.1.1 Fast Particle Impact.- 5.1.2 Thermal Collisions.- 5.1.3 Excitation by Thermal Electrons.- 5.1.4 Discharge Mechanisms and Heating by Electric Fields.- 5.2 Deactivation.- 5.3 Interpretation of the Spectrum.- 5.3.1 Atomic Lines.- 5.3.2 The Intensity Distribution within Molecular Band Systems.- 5.4 The Lifetime of Metastable Oxygen Atoms.- 5.5 Helium Emissions.- 5.6 Sunlit Aurora.- Appendix (References to Data on Cross-Sections).- References.- 6 Temperature Determinations from Auroral Emissions.- 6.1 Introduction.- 6.2 Doppler Temperatures.- 6.3 Rotational Temperatures.- 6.4 Conclusions and Prospects.- References.- 7 Pulsing Aurora.- 7.1 Introduction.- 7.2 Pulsating Aurora.- 7.2.1 Definition.- 7.2.2 Observations.- 7.3 Flaming Aurora.- 7.4 Flickering Aurora.- 7.5 Streaming Aurora and Horizontal Waves.- 7.6 Correlation with Pulsations in the Magnetic Field and Telluric Currents.- 7.7 Correlation with Pulsations in X-Rays.- 7.8 Morphology of Pulsating Aurora.- References.- 8 Optical Aurora and Radio Observations.- 8.1 Introduction.- 8.2 Radio Absorption.- 8.3 E-Layer Ionization.- 8.4 Radio Auroras.- 8.5 VLF Radio Emissions and Radio Noise.- 8.6 Polar Cap Absorption (PCA) Events.- References.- 9 Auroral X-Rays.- 9.1 Production of X-Rays in Aurora.- 9.2 Observations.- References.
TL;DR: The scope of fossil cosmic-ray track studies in extraterrestrial samples has been increased, because olivine is often an abundant constituent and because it has a higher threshold ionization for track registration and has lower uranium, thorium, and trace element concentrations as compared with pyroxenes and feldspars.
Abstract: A one-step, three-component aqueous etchant was developed for revealing the tracks of charged particles in olivine. The etchant reveals tracks of small cone angle, which are equally well developed in all the crystallographic directions. The scope of fossil cosmic-ray track studies in extraterrestrial samples has thus been increased, because olivine is often an abundant constituent and because it has a higher threshold ionization for track registration and has lower uranium, thorium, and trace element concentrations as compared with pyroxenes and feldspars. The etchant does not attack any of the principal rock-forming minerals in normal etching time, which allows a nondestructive study of fossil tracks in thin-section mounts. The study of fossil cosmic-ray tracks in olivine is particularly valuable for investigations of very, very heavy cosmic-ray nuclei and for highly irradiated samples such as those found in the lunar regolith.
TL;DR: In this article, the spectrum of singly ionized neon emitted by a hollow-cathode discharge has been observed in the 11 000-300? range, and the derived term system has been fixed in relation to the ground term using improved values for the wavelengths of the resonance lines 2s22p52P1?,?-2s2p62S? at 460.7284 and 462.3908?.
Abstract: The spectrum of singly ionized neon emitted by a hollow-cathode discharge has been observed in the 11 000-300 ? range. Wavelengths have been determined for 1 250 Ne II lines of which about 950 are new. The extended wavelength observations have led to the finding of more than 220 new energy levels, which means that in all 301 Ne II levels, belonging to the configurations 2s22p5, 2s2p6, 2s22p43s-7s, 3p-5p, 3d-5d, 4f-9f, and 5g-7g are now known. The derived term system has been fixed in relation to the ground term using improved values for the wavelengths of the resonance lines 2s22p52P1?,?-2s2p62S? at 460.7284 and 462.3908 ?. The 3P2 ionization limit has been determined to be (330 388.6?0.3) cm-1 above the ground level. Accurate wavelengths, useful as reference wavelengths, have been calculated in the 2 000-1 000 ? and 460-300 ? regions.
TL;DR: In this article, a statistical weighting procedure is used to calculate the fluorescence yields omega K and omega L23 for various defect atomic configurations of the argon atom and the changes in fluorescence yield which accompany atoms with multiple vacancies in various shells should be included when determining inner shell ionization cross sections from X-ray data in heavy ion-atom collision studies.
Abstract: A statistical weighting procedure is used to calculate the fluorescence yields omega K and omega L23 for various defect atomic configurations of the argon atom. The changes in fluorescence yield which accompany atoms with multiple vacancies in various shells should be included when determining inner shell ionization cross sections from X-ray data in heavy ion-atom collision studies. The general features discussed may be important for solid as well as gaseous targets.
TL;DR: In this paper, high-resolution photoelectron spectra of F2, Cl2, Br2, I2 and ICl are reported and interpreted in terms of the electronic structures of these molecules.
Abstract: High-resolution photoelectron spectra of F2, Cl2, Br2, I2, ICl and IBr are reported and interpreted in terms of the electronic structures of these molecules. Vertical and adiabatic ionization potentials as well as vibrational data are given for the ionized states arising from the removal of an electron from each molecular orbital. Where possible, these values are related to the emission spectra of the molecular ion and to the vacuum u.-v. spectra of the neutral species.
01 Jun 1971
TL;DR: In this article, a method is described for tracing theoretically the growth in space and time of a rapidly developing gaseous discharge between parallel-plate electrodes where the electric field is distorted by the space charge of the electrons and ions.
Abstract: A method is described for tracing theoretically the growth in space and time of a rapidly developing gaseous discharge between parallel-plate electrodes where the electric field is distorted by the space charge of the electrons and ions. The results obtained for a discharge in nitrogen initiated by a pulse of electrons leaving the cathode have been used to simulate streak photographs of the light output from the discharge. There is excellent agreement between the present results and the experimental streak photographs of Wagner. It is concluded that the occurrence of the anode- and cathode-directed streamers can be satisfactorily explanined in terms of the basic Townsend ionisation processes, provided that space-charge distortion of the field is allowed for correctly.
TL;DR: Using an energy-resolved electron beam, ionization potentials for the following free radicals have been measured: vinyl 8.95 V, allyl 8.07 V, benzyl 7.27 V as mentioned in this paper.
Abstract: Using an energy-resolved electron beam, ionization potentials for the following free radicals have been measured: vinyl 8.95 V, allyl 8.07 V, benzyl 7.27 V. For vinyl and allyl ions new measurements of thresholds for dissociative ionization give ΔHf(C2H3+) = 266 kcal/mol and ΔHf(C3H5+) = 226 kcal/mol, leading to neutral radical heats of formation ΔHf(C2H3) = 59.6 kcal/mol and ΔHf(C3H5) = 40 kcal/mol. The data for benzyl radical and ion give ΔHf(benzyl cation) = 213 kcal/mol.
NATO1
TL;DR: In this paper, the high resolution He I photoelectron spectrum of the (a12t25)2T2 < - (a 12t26)1A1 transition in methane has been recorded and analyzed and a value has been obtained for the adiabataic ionization potential.
Abstract: The high resolution He I photoelectron spectrum of the (a12t25)2T2 < - (a12t26)1A1 transition in methane has been recorded and analyzed and a value has been obtained for the adiabataic ionization potential. The electron spectrum resulting from ionization of a t2 electron is a composite of at least three overlapping electronic bands which are separated by several tenths of an eV. These bands are the split components of the 2T2 electronic state of the CH4+ ion which is distorted by strong Jahn-Teller forces. The symmetry of the molecule in these three electronic states is believed to be, in order of increasing energy, D2d
TL;DR: In this paper, the first adiabatic ionization potential was found to be 10.87 plus or minus 0.01 eV for a number of strong Rydberg transitions above 1200 A.
Abstract: The measurements have been conducted in the spectral range from 600 to 2000 A. Integrated oscillator strengths were determined for a number of strong Rydberg transitions above 1200 A. From the photoionization curve the first adiabatic ionization potential was found to be 10.87 plus or minus 0.01 eV. As an aid in interpreting the absorption spectrum, theoretical calculations were made using a single-configuration self-consistent field procedure for the Rydberg states and a model which included mixing between the Rydberg and valence states.
TL;DR: In this article, it was shown that short-period (τ < 30 min) disturbances in the F region may be appreciably affected by spatial resonance, if the component of E×B/B2 drift in the wave normal direction is equal to the phase velocity of the wave.
Abstract: Internal gravity waves in the neutral air propagating through the ionosphere cause a corresponding disturbance in the ionization. This note discusses additional effects that arise owing to the presence of an electrostatic field and background wind and in particular the possibility of a ‘spatial resonance’ when the natural drift of ionization irregularities equals the phase velocity of the gravity wave. The electrostatic field may be the one associated with the tidal motions that drive the Sq current system. It is shown that short-period (τ<30 min) disturbances in the F region may be appreciably affected by spatial resonance, if the component of E×B/B2 drift in the wave normal direction is equal to the phase velocity of the wave. In the E region a similar coincidence between the ion drift velocity and the wave phase velocity may cause intense patches of sporadic E to drift almost with the background wind at the sporadic E height.
TL;DR: In this paper, a defect structure which incorporates singly and doubly ionized nonstoichiometric oxygen vacancies and acceptor states was inferred from the agreement between the theoretically derived relation and the experimentally observed O2-partial pressure and temperature dependence of the conductivity.
Abstract: A defect structure which incorporates singly and doubly ionized nonstoichiometric oxygen vacancies and acceptor states, presumably associated with impurities, was inferred from the agreement between the theoretically derived relation
and the experimentally observed O2-partial-pressure and temperature dependence of the conductivity. This relation describes the behavior over the entire O2 pressure and temperature range investigated. A simplified defect model gave good agreement for the limiting case where n> >p but was shown to be in error compared with the more comprehensive relation above. The standard enthalpies of formation for singly and doubly ionized O vacancies in BaTiO3, are 4.3 and 5.7 eV, respectively. The difference between these values, 1.4 eV, corresponds to a donor energy level which lies near the middle of the band gap.
TL;DR: In this article, the combination of glow discharge sputtering and mass spectrometry was used for determining the composition of thin surface layers of solids, and the results showed that the sensitivity was comparable for all elements except He, Ne, and F and is independent of the matrix in which the species are contained.
Abstract: It is shown that the combination of rf glow‐discharge sputtering and mass spectrometry provides a very sensitive method for determining the composition of thin surface layers of solids. The sample is immersed in an rf sputtering glow discharge and a fraction of those sputtered atoms which are ionized in the discharge by Penning ionization are monitored with a quadrupole mass filter. 1011 sputtered atom/sec can readily be detected and considerable improvement in sensitivity can easily be anticipated. The sensitivity is comparable for all elements except He, Ne, and F and is independent of the matrix in which the species are contained; i.e., standards are not required. The matrix can be electrically insulating or conducting.