Mark G. Inghram

ISOTOPIC COMPOSITION AND DISTRIBUTION OF LEAD, URANIUM, AND THORIUM IN A PRECAMBRIAN GRANITE

The isotopic compositions and concentrations of lead and uranium have been determined in some separated minerals and the composite of a granite from Monmouth township, Haliburton County, Ontario. The chemical and mass spectrometric methods that were used are described. The age of the zircon from the granite is 1050 million years. Much of the lead, uranium, and thorium exists in chemically unstable and presumably interstitial phases of the granite. A comparison of the observed amounts of uranium, thorium, and lead in the various minerals with those amounts that should have been present, had these three elements existed within the minerals as closed systems, shows a non-balance of these elements in every case. It appears that the granite as a whole has closely approximated a closed system since it was formed with respect to uranium and its decay products, but has been an open system with respect to thorium and its decay products. Interpretations concerning the relationship of these data to lead ores are discussed.

Polymeric Gaseous Species in the Sublimation of Molybdenum Trioxide

Mass spectometric analysis of the vapor in thermodynamic equilibrium with powdered molybdenum trioxide, as sampled from a Knudsen effusion cell, has shown that the vapor phase consists predominantly of Mo3O9, Mo4O12 and Mo5O15 molecules. Utilizing the Clausius‐Clapeyron equation, individual heats of sublimation have been determined to be 80.5±1.5, 93.6±1.6 and 105.6±3.5 kcal/mole respectively at 850° K. The heats of formation and third law entropies have been evaluated for each of these molecules.

Surface Ionization Source Using Multiple Filaments

A new multiple filament surface ionization source has been developed for mass spectrometry which for several of the elements is many times more efficient than the usual single filament surface ionization source. Emission from the source can be shifted from the oxide to the metal position or vice versa by appropriate adjustment of temperatures. Because of the high efficiency of the source it is possible to look at the sample during a number of successive evaporations. Use of this source should eliminate the necessity of using electron multiplier ion detection for some elements.

Polymeric Gaseous Species in the Sublimation of Tungsten Trioxide

Mass spectrometric study of the gaseous species effusing from a Knudsen cell filled with WO3 has shown that WO3(s) sublimes to form the gaseous molecules W3O9, W4O12, and W5O15. From the measured partial pressures for these species and their variations with temperature, ΔH, ΔF0, and ΔS0 of sublimation are obtained.

Mass Spectrometric Study of Barium Oxide Vapor

Ions formed by electron bombardment of the vapor in thermodynamic equilibrium with BaO solid have been studied mass spectrometrically. The BaO solid was heated in a Knudsen cell and a sample of the effusing vapor entered the ion source of a mass spectrometer. At cell temperatures between 1500°K and 1800°K, ion currents of Ba+, BaO+, Ba2O+, Ba2O2+, and Ba2O3+ were observed. The variations of ion intensities with temperature were measured and appearance potential curves were obtained. Possible mechanisms of ion formation were considered, and evidence for the existence of gaseous molecular species of BaO, Ba2O, Ba2O2, and Ba2O3 was obtained. The major molecular species, effusing from the Knudsen cell, was BaO. A thermodynamic treatment of ion currents yields the following heats of reaction BaO(s)=BaO(g);           ΔH0∘=104±4 kcal/moleBaO(g)=Ba(g)+O(g);      ΔH0∘=130±5 kcal/moleBa2O2(g)=2BaO(g);        ΔH1700∘=89±11 kcalBa2O(g)=Ba(g)+BaO(g);  ΔH1700∘=93±17 kcal.

Thermodynamics of the Ta–O System : The Dissociation Energies of TaO and TaO2

Mass spectrometric analysis of the vapor in thermodynamic equilibrium with mixtures of Ta(s) and Ta2O5(s) has shown TaO and TaO2 to be the predominant gaseous molecules present. The experimental data yield 8.4±0.5 ev and 15.0±0.5 ev for the energies of atomization of these molecules at 0°K.

Thermodynamics of the V–O System : Dissociation Energies of VO and VO2

The molecules vaporizing from V2O5(s) and VO(s) have been determined employing a mass spectrometer to analyze the vapors effusing from Knudsen cells containing these materials. The vapor over the V2O5 loaded cells was found to contain V4O10(g), V6O14(g), V6O12(g) with some evidence for V4O8(g) and V2O4(g). Since both the composition and the partial pressures varied with time no quantitative data could be obtained for these molecules. By contrast, both the composition and partial pressures of the vapor over VO(s) were essentially constant with time. The molecules observed were V(g), VO(g), and VO2(g). A thermodynamic treatment of the data yields 6.4±0.2 ev and 12.8±0.2 ev, respectively, for the atomization energies of VO and VO2.

Thermodynamics of the Zr‐ZrO2 System : The Dissociation Energies of ZrO and ZrO2

A mass spectrometric analysis of vapors effusing from a Knudsen cell containing either solid ZrO2 or a mixture of Zr and ZrO2 powders has been employed to determine the vapor pressures, and hence the heats of sublimation of these species. Combined with published thermodynamic data, these results yield 7.8±0.2 ev and 14.5±0.2 ev for the dissociation energies of ZrO and ZrO2, respectively. Previous work is shown to be in error due to the volatility of TaO.

ISOTOPIC COMPOSITIONS OF QUATERNARY LEADS FROM THE PACIFIC OCEAN

Knowledge of the variations of the isotopic composition of marine leads with time will provide the basis for further studies concerning the general problems of the evolution of the earths crust and specific problems of the histories of localized sedimentary bodies. Important aspects of the acquisition of this knowledge are: (1) factors in the processes of weathering and transport to the oceans which may result in selective enrichment or depletion of the isotopes of lead in oceanic waters; (2) the form in which lead exists in oceanic waters and the influence this may have upon the factors of mixing and of incorporation into sedimentary deposits by the different mechanical, electrochemical, and biological mechanisms; and (3) obtaining samples from marine sedimentary deposits which contain lead representative of the marine hydrosphere and which has not been altered by mixing with leads of different isotopic compositions from other sources after these deposits were formed.

Massenspektrometrische Untersuchungen der Feldemission positiver Ionen

Massenspektrometrische Untersuchungen der in der Nähe und an der Oberfläche einer Spitze eines Feld-Emissions-Mikroskops (FEM) erzeugten positiven Ionen erläutern den Mechanismus von lonisierungsvorgängen und weisen auf verschiedene Anwendungen hin. Letztere bestehen in einer Bestimmung der Dissoziationsprodukte bei Chemisorption, Analyse von Gasmischungen, Nachweis und Messung kurzlebiger Zwischenprodukte, freier Radikale und so weiter.