Showing papers on "Ion published in 1976"
TL;DR: In this paper, a theoretical argument is developed to find in which conditions this ion evaporation can occur; to that end solvation free enthalpies of cluster ions are derived from existing experimental data and the absolute reaction rate theory is applied.
Abstract: Experiments are briefly reported which show that small ions separate or ’’evaporate’’ from evaporating droplets carrying electrical charges. A theoretical argument is developed to find in which conditions this ion evaporation can occur; to that end solvation free enthalpies of cluster ions are derived from existing experimental data and the absolute reaction rate theory is applied. The conditions for ion evaporation are compared with those for Rayleigh instability and it is shown that the first process should occur only when the drop reaches sizes of the order of 10−6 cm. The ion evaporation process must be operative in the evaporation of highly electrified cloud droplets when their solute concentration is low.
1,267 citations
TL;DR: In this paper, the flux density of ions created by ionization of interstellar neutral particles in the solar system and picked up by the solar wind is calculated as a function of the neutral particles.
Abstract: The flux density of ions created by ionization of interstellar neutral particles in the solar system and picked up by the solar wind is calculated as a function of the neutral particles. For atomic hydrogen the flux density is estimated to exceed 10,000/sq cm/sec over the distance range from a few to nearly 100 AU. The velocity space distribution of the interstellar ions is calculated under the assumption of no significant energy diffusion but with inclusion of adiabatic effects as well as a possible strong pitch angle diffusion. The energy spectrum is highly nonthermal and much broader than that of the solar wind ions; interstellar protons are easily distinguishable from solar wind protons by their location in velocity space. If charge exchange is an important contributor to the ionization of hydrogen, the observed local intensity of interstellar protons should exhibit time variations correlated with the density changes of the solar wind stream structure.
355 citations
TL;DR: In this paper, a mass-selected, low-energy, positive ion beam, derived from a gas-discharge source in conjunction with a quadrupole mass filter, is injected into a flowing gas.
337 citations
01 Jan 1976
TL;DR: In this article, the authors used a high resolution Magnetic Spectral Resonance Spectrometer (MRS) to measure the depth profile of a single particle from backscattering spectra.
Abstract: of Volume 1.- I. Energy Loss and Straggling.- The Treatment of Energy-Loss Fluctuations in Surface-Layer Analysis by Ion Beams.- Evidence of Solid State Effects in the Energy Loss of 4He Ions in Matter.- Empirical Stopping Cross Sections for 4He Ions.- Determination of Stopping Cross Sections by Rutherford Backscattering.- Depth Profiling of Implanted 3He in Solids by Nuclear Reaction and Rutherford Backscattering.- Energy Loss Straggling of Protons in Thick Absorbers.- Energy Dependence of Proton Straggling in Carbon.- Energy Straggling of 4He Ions in Al and Cu in the Backscattering Geometry.- Energy Spreading Calculations and Consequences.- Analysis of Nuclear Scattering Cross Sections by Means of Molecular Ions.- II. Backscattering Analysis.- Determining Concentration vs. Depth Profiles from Backscattering Spectra without Using Energy Loss Values.- Comparative Analysis of Surface Layers by Backscattering and by Auger Electron Spectroscopy.- Analyzing the Formation of a Thin Compound Film by Taking Moments on Backscattering Spectra.- Computer Analysis of Nuclear Backscattering.- Some Practical Aspects of Depth Profiling Gases in Metals by Proton Backscattering: Application to Helium and Hydrogen Isotopes.- Depth Profiling of Deuterium and Helium in Metals by Elastic Proton Scattering: A Measurement of the Enhancement of the Elastic Scattering Cross Section over Rutherford Scattering Cross Section.- Near-Surface Investigation by Backscattering of N+ Ions and Grazing Angle Beam Incidence.- The Application of Low Angle Rutherford Backscattering to Surface Layer Analysis.- Measurement of Projected and Lateral Range Parameters for Low Energy Heavy Ions in Silicon by Rutherford Backscattering.- Range Parameters of Heavy Ions in Silicon and Germanium with Reduced Energies from 0.001 ? ? ? 10.- On Problems of Resolving Power in Rutherford Backscattering.- Studies of Surface Contaminations, Composition and Formation of Superconducting Layers of V, Nb3Sn and of Tunneling Elements Using High Energetic Protons Combined with Heavy Ions.- Determination of Implanted Carbon Profiles in NbC Single Crystals from Random Backscattering Spectra.- Pore Size from Resonant Charged Particle Backscattering.- Measurement of Thermal Diffusion Profiles of Gold Electrodes on Amorphous Semiconductor Devices by Deconvolution of Ion Backscattering Spectra.- Enhanced Sensitivity of Oxygen Detection by the 3.05 MeV (?,?) Plastic Scattering.- Progress Report on the Backscattering Standards Project (Abstract).- III. Applications of Backscattering and Combined Techniques.- Ion Beam Studies of Thin Films and Interfacial Reactions.- Studies of Tantalum Nitride Thin Film Resistors.- Investigation of CVD Tungsten Metallizations on Silicon by Backscattering.- Ion Beam Analysis of Aluminium Profiles in Heteroepitaxial Ga1-xAlxAs-Layers.- Analysis of Ga1-xA1xAs-GaAs Heteroepitaxial Layers by Proton Backscattering.- Interdiffusion Kinetics in Thin Film Couples.- Backscattering and T.E.M. Studies of Grain Boundary Diffusion in Thin Metal Films.- The Analysis of Nickel and Chromium Migration Through Gold Layers.- Applications of Ion Beam Analysis to Insulators.- Lithium Ion Backscattering as a Novel Tool for the Charac terization of Oxidized Phases of Aluminum Obtained from Industrial Anodization Procedures.- Investigation of an Amino Suger-Like Compound from the Cell Walls of Bacteria Using Backscattering of MeV Particles.- IV. Equipment.- Versatile Apparatus for Real-Time Profiling of Interacting Thin Films Deposited in Situ.- Application of a High-Resolution Magnetic Spectrometer to Near-Surface Materials Analysis.- Rutherford Backscattering Analysis with Very High Depth Resolution Using an Electrostatic Analysing System.- An Apparatus for the Study of Ion and Photon Emission from Ion Bombarded Surfaces: I. Some Preliminary Results.- Author Index.
286 citations
TL;DR: In this paper, it was shown that the defect energy required for the formation of a defect pair greatly exceeds the thermal energy, kBT, in a typical ionic crystal, and the same is true of the ionic conductivity.
230 citations
TL;DR: In this article, the authors measured the emf of a galvanic cell within the temperature range between 700° and 800°C as a function of the oxygen partial pressure at which the ionic transference number of the solid solution becomes 0.5.
Abstract: The solid solutions exhibit high ionic conduction due to the migration of O2− ions via oxygen ion vacancies. The emf of a galvanic cell,, is measured within the temperature range between 700° and 800°C as a function of . At such high oxygen pressures as in air, the emf changes according to indicating the ionic transference number in the solid solution is unity. With decreasing oxygen pressure, however, the observed emf becomes smaller than the theoretical value. This indicates the onset of electronic conduction generated by the reduction of the solid solution. The dependence of the emf on is described bywhere is a constant corresponding to the oxygen partial pressure at which the ionic transference number of the solid solution becomes 0.5. From the temperature dependence of , partial molar enthalpy changes for the reduction of are calculated.
227 citations
IBM1
TL;DR: In this paper, the Hartree-Fock-Slater charge distribution for the target atom with Bonderup and Hvelplund's formulation was calculated for protons and helium ions in each of the elements.
Abstract: Energy straggling has been calculated for protons and helium ions in each of the elements, by using the Hartree-Fock-Slater charge distribution for the target atom with Bonderup and Hvelplund's formulation. The results reveal a ${Z}_{2}$ structure in energy straggling, and afford a ready explanation of some earlier measurements.
227 citations
TL;DR: In this article, a wide range of dissociation reactions are described and the intensity relationships yield information about the structure of the ions concerned and also permit conclusions to be drawn about the mechanism of their formation.
Abstract: Organic ions with high translational energy colliding inelastically with neutral atoms or molecules become excited electronically at the expense of their translational energy. The excitation energy enables a wide range of dissociation reactions to occur and the intensity relationships yield information about the structure of the ions concerned and also permit conclusions to be drawn about the mechanism of their formation.
224 citations
TL;DR: In this article, X-ray scattering measurements have been carried out for concentrated aqueous solutions of divalent transition-metal perchlorates of manganese(II) to zinc(II).
Abstract: X-ray scattering measurements have been carried out for concentrated aqueous solutions of divalent transition-metal perchlorates of manganese(II) to zinc(II). The radial distribution curves showed that each central metal ion was octahedrally surrounded by six water molecules at the distances of 2.20 A for Mn2+–OH2, 2.12 A for Fe2+–OH2, 2.08 A for Co2+–OH2, 2.04 A for Ni2+–OH2, and 2.08 A for Zn2+–OH2. The results from the radial distribution curves were confirmed by the direct analysis of reduced intensities. Concentrated aqueous solutions of copper(II) and zinc(II) sulfates have also been measured. The bond distances of 1.94 A for the Cu2+–OH2 (equatorial), 2.38 A for the Cu2+–OH2 (axial) and 2.08 A for Zn2+–OH2 were consistent with those obtained for the perchlorate solutions. No evidence for the contact ion pairs of metal and sulfate ions was found by the present X-ray measurements. The bond energies between metal ions including copper ion were discussed by application of the Garrick model with a sligh...
207 citations
TL;DR: From classical perturbation theory, it is concluded that elastic scattering mainly determines the real part of the optical potential in a point slightly inside the distance of closest approach for a trajectory leading to the rainbow angle.
TL;DR: In this paper, the Fokker-Planck equation for an energetic ion beam injected into a magnetized plasma consisting of Maxwellian ions and electrons with υthi ≪υb≪ υthe was studied.
Abstract: The Fokker-Planck equation is studied for an energetic ion beam injected into a magnetized plasma consisting of Maxwellian ions and electrons with υthi ≪υb≪ υthe. The time evolution of the fast ion distribution is given in terms of an infinite sum of Legendre polynomials for distributions that are axisymmetric about the magnetic field. The effect of charge exchange is included. The resulting ion distribution is somewhat isotropic for velocities much less than the injection velocity, however, the distribution is sharply peaked in both energy and pitch angle for velocities near the injection velocity. Approximate asymptotic expressions are given for the distribution in the vicinity of the injected beam and for velocities greater than the injection velocity. The effect of a weak parallel electric field is also given.
TL;DR: Changes are induced in the electron spin resonance signal amplitude and microwave power saturation of the naturally occurring free radical in melanin by bound paramagnetic ions, which are magnetic in nature and not, as has been supposed, chemical.
Abstract: Changes are induced in the electron spin resonance signal amplitude and microwave power saturation of the naturally occurring free radical in melanin by bound paramagnetic ions. The changes serve as experimental observables in competition experiments between diamagnetic and paramagnetic metal ions for melanin binding sites and between melanin and ethylenediaminetetraacetic acid for paramagnetic metal ions. Evidence is presented for the existence of several specific types of metal binding sites. The interaction of copper with free radicals leading to loss of electron spin resonance signal amplitude is magnetic in nature and not, as has been supposed, chemical.
TL;DR: The results for the He++N2 reaction agree with the previously established branching ratio and considerable differences are apparent between the product distributions obtained and those previously reported and an explanation is attempted.
Abstract: The reactions of He+ ions with N2, O2, CO2, and CH4, and of C+ and N+ ions with O2 are presented. The measurements were carried out in the SIFT apparatus (selected ion flow tube), which involves the injection of a mass-selected positive-ion beam into a flowing neutral gas into which a reactant gas is introduced at a position downstream in the flow. Data acquisition and analysis are made by the flowing afterglow technique. The results for the He++N2 reaction agree with the previously established branching ratio. For the other reactions, considerable differences are apparent between the product distributions obtained and those previously reported and an explanation is attempted. A brief discussion of the reaction mechanism is presented for each reaction in the light of the determined product distributions, and the anticipated development of the SIFT technique for ion-molecule reaction mechanisms is outlined.
TL;DR: In this paper, the thermodynamic properties of one-component ionic plasmas in a responding (polarized) background of fully degenerate electrons are calculated over a wide range of temperatures and densities.
Abstract: The thermodynamic properties of one-component ionic plasmas in a responding (polarized) background of fully degenerate electrons are calculated over a wide range of temperatures and densities The weak and intermediate screening regimes are treated by two complementary methods which take the one-component plasma in a rigid background as a starting point Thermodynamic perturbation theory is used in the weakly screened ionic plasma typical of white-dwarf matter; this leads to simple, analytic expressions for the thermodynamic properties Relativistic effects in the very dense electron gas are considered explicitly A variational method, based on the Gibbs-Bogolyubov inequality, and the physical idea of an effective charge reduction of the ions, yields satisfactory results in the intermediate screening regime typical of the deep interior of Jupiter Our results are in good agreement with the available Monte Carlo data and represent a significant improvement over previous calculations based on a hard-sphere reference system
TL;DR: In this article, the repulsive potential energy between the ions i and j is specified by the nature of each ion as: (ρ i + ρ j ) exp[(ρ i+ ρ n − r) (ρ n + π j ) ] as a function of the interionic distance r. In this expression, qi and ρi are the ionic radius and ionic compressibility.
TL;DR: In this article, the authors show that the relative yields of singlets and triplets change with time as the spin correlation decays, and that the process is a coherent one resulting from the isotropic hyperfine interaction with hydrogen nuclei.
Abstract: Geminate recombination of radical ions of aromatic hydrocarbons in alkanes produces excited molecules: the relative yields of singlets and triplets change with time as the spin correlation decays. At short times ([graphic omitted] 50 ns) the process is a coherent one resulting from the isotropic hyperfine interaction with hydrogen nuclei: its rate is field-dependent and, for mobile liquids, it can be calculated exactly from e.s.r. data: deuteration will have a large effect and oscillations may be observed. At longer times, the yields became constant (but different) at high and zero field, but an additional small decay is predicted for very low fields. At still longer times, random spin relaxation will eventually make the yields independent of field. The theory is extended to cover initial production of triplet ion pairs in addition to singlets, the effect of charge transfer and recombination in viscous liquids and solids. It is applied to excited state production in radiolysis and to the radiation chemistry of pure alkanes.
TL;DR: In this paper, the authors derived threshold laws for photodetachment of electrons from polyatomic negative ions and derived the general form for the limiting behavior at threshold using group theory and symmetry considerations.
Abstract: Threshold laws for the cross section for photodetachment of electrons from polyatomic negative ions are derived. The general form for the limiting behavior at threshold is derived using group theory and symmetry considerations. In addition, for energies within a few eV of threshold, a formulation using the Born approximation with partial orthogonalization is developed. The energy dependence of the photodetachment cross section for molecular negative ions is computed and shown to agree well with experimentally determined cross sections.
TL;DR: In this paper, it was shown that the protons are succeeded by He+ ions as the dominant species in the ring current during the recovery phase, based on observations of hydrogen and helium emissions at low altitudes near the magnetic equator and observations of the evolution with time of pitch angle distributions in ring current itself.
Abstract: Calculated lifetimes of ring current protons against charge exchange with geocoronal hydrogen amount to only a few hours for energies below about 50 keV. The much longer lifetime for He+ ions leads to the conclusion that the protons are succeeded by He+ ions as the dominant species in the ring current during the recovery phase. Observations of hydrogen and helium emissions at low altitudes near the magnetic equator and observations of the evolution with time of pitch angle distributions in the ring current itself support this conclusion. (See the companion paper by Lyons and Evans (1976).)
TL;DR: A modified version of the charge-pulse relaxation technique with improved time resolution was applied to the study of transport kinetics of hydrophobic ions through lipid bilayer membranes, and the results support the model proposed earlier.
TL;DR: In this article, the elastic part of the interaction of low energy rare gas ions is interpreted in terms of the binary collision model and the possible neutralization processes, Auger-neutralization and quantum-mechanical phase interference neutralization, are discussed in detail.
TL;DR: In this paper, the branching ratios for photoionization to various ion states of CO and N 2 have been measured in the energy range 18-50 eV using an electron-electron coincidence technique at an ejected electron angle of 90°.
TL;DR: In this paper, a modified Nielsen ion source with circular end extraction was investigated to increase lifetime, temperature and ionization efficiency of the ion source under stable discharge conditions and to reduce the ion current density of low intensity separator sources.
TL;DR: In this article, a Wannier-like stationary configuration of slow electrons in the field of a residual ion is shown and solutions of the Schrodinger equation in this limited region of space are obtained and applied to the investigation of the cross section for multiple ionization near threshold.
Abstract: Many slow electrons in the field of a residual ion are shown to have Wannier-like stationary configurations. Solutions of the Schrodinger equation in this limited region of space are obtained and applied to the investigation of the cross section for multiple ionization near threshold. Numerical results are presented for double escape in several spin and angular momentum states and for triple escape in the 2S and 4S states.
TL;DR: A theoretical treatment of diffusion-limited ion transport through pores is given which takes both concentration and electric potential gradients into account as driving forces for the flow of ions.
TL;DR: In this article, the authors used tantalum diaphragms on the surface of yttrium iron garnet (YIG) to measure the charge build-up caused by bombardment of insulating samples with energetic particles.
Abstract: The generation of charge build‐up, caused by bombardment of insulating samples with energetic particles, and its role in altering the relative secondary‐ion currents and reducing their absolute values, sometimes even to zero, are discussed. Proposed methods for charge reduction by bombardment with negative ions or with neutral particles, or by use of an auxiliary electron beam or spray gun, are shown to be not useful in every experimental situation. A further method involving introduction of an auxiliary conducting electrode when using negative primary ions is considered mechanistically, and tested by placing tantalum diaphragms onto the surface of yttrium iron garnet (YIG). The final charging values and mass spectra thus obtained are compared to those measured when using bare and metallic grid‐covered surfaces of the same YIG sample. The satisfactory results achieved with the diaphragm show that SIMS analyses of insulators can be performed in a simple, quick, and inexpensive manner.
TL;DR: In this article, the chemical and physical effects of 10−15 keV H1+, D1+ and He+ ion bombardments to graphite and SiC have been conducted using the techniques of Raman scattering and scanning electron microscopy (SEM).
TL;DR: In this article, the gallium ion vacancies are the mobile point defects in β -Ga 2 O 3 single crystals in the temperature range 300-1250 K and up to about 900 K.