Charles E. Melton

Cross Sections and Interpretation of Dissociative Attachment Reactions Producing OH−, O−, and H− in H2O

Dissociative‐electron‐attachment cross sections for the production of OH−, O−, and H− from water vapor have been determined. These cross sections are discussed within the framework of resonance scattering theory. The relatively low cross sections for the production of OH−, 1.2, 0.85, and 0.85× 10−21 cm2 molecule−1 for maxima of 6.4, 8.4, and 11.2 eV, suggest that the atoms in the H2O− complex are loosely bound together and behave as essentially independent entities. All of the negative ions from H2O appear to be produced from three different electronic states of the molecule. Results from this study are used to draw a hypothetical potential energy diagram for H2O.

Some petrological aspects of the Prairie Creek diamond-bearing kimberlite diatreme, Arkansas

Based on modal and chemical composition, the rocks of the Prairie Creek diatreme situated 4 km SSE of Murfreesboro, Pike County, Arkansas, are classified as micaceous kimberlite. The K-Ar isotopic analysis of phlogopite from this diatreme yielded an age of 106 ± 3 m.y. (Albian) which is in agreement with stratigraphic relations. Electron beam probe data on minerals from kimberlite breccia, one of the three textural types, are presented. The breccia is considered as the potential source of the diamonds that have been mined at the diatreme. It contains phenocrysts of olivine (Fo90–92) and serpentine pseudomorphs after olivine embedded in a groundmass of serpentine, minor calcite, chrome-diopside, phlogopite (Mg/Mg+Fe = 84.15%), perovskite, spinels, and pentlandite. Xenoliths of shales, sandstones, and mantle-derived ultramafic material are also present. Spinels are rich in Cr, Ti, and Fe and generally low in Al. Zoned spinels show enrichments in Ti and Fe towards their rims. A positive correlation between 100(Fe3++Ti)/(Cr+Al+Fe3++Ti) and 100 Mg/(Mg+Fe2+) ratios exists in these spinels and probably reflects an oxygen fugacity increase during magma crystallization. Occluded gases in diamonds and kimberlites corroborate the hypothesis that the parent magma of the Prairie Creek kimberlite was derived by partial melting of upper-mantle garnet lherzolite under volatile-rich conditions, primarily enriched in H2O and CO2.

The mass spectrometer as a radiolytic and catalytic laboratory

Abstract Changes in our physical concepts, mathematical methods and philosophical thought have been elicited by the development of the field of mass spectrometry. From its inauspicious beginning more than half a century ago, the mass spectrometer hase evolved to a stage where it can be used as a complete self-contained research laboratory. Versatile ion sources have been developed to operate in the pressure range, 10-9 to 10 or more torr. in a specific application as a research laboratory, the first step is to select the proper type of ion source. In this report, four different types of specialized ion sources available for research are described briefly. An application of each of these sources to a representative problem is given. For a problem in radiation chemistry, it is shown that the elementary steps of the reaction can be followed in temporal sequence starting about 10-14 sec after irradiation and continuing until final products appear. More importantly, it is shown that the results are not restricted to either chemical (e.g. radical—molecule interactions) or physical (e.g. ionization) reactions, but rather, both types can be studied. The developments in mass spectrometry, however, have not completely eliminated the need for other scientific instrumentation. Instead the mass spectrometer is often used in conjunction with other instruments to extend the domain of each.

Composition and volume of gas released by crushing coal from West Virginia, Kentucky and Alabama

Abstract Analyses of the composition and volume of gaseous inclusions in samples of coal from West Virginia, Alabama and Kentucky have been made at room temperature by mass spectrometric techniques. This was done by crushing the coal in the high-vacuum inlet system of a research mass spectrometer. The gases observed were composed of C, S, H, O, N, He and Ar atoms. Water was the most abundant gas; others were hydrogen, helium, methane, ammonia, methanol, ethanol, carbon monoxide, nitrogen, ethane, oxygen, hydrogen sulphide, argon and carbon dioxide. Gas compositions were found to be a function of the source of the coal. For example, over 6% of the gas from Alabama coal was methane, but West Virginia coal contained only 0.1% methane. The volume of gas also was a function of the coal source. Coal from Kentucky contained 2.3 cm 3 g −1 (STP), whereas coal from West Virginia contained 0.4 cm 3 g −1 .

Composition and volume of gas released by ‘melting’ coal from West Virginia and Alabama

Abstract Analyses of the composition and volume of gases released by ‘melting’ samples of coal from West Virginia and Alabama under vacuum have been made by mass spectrometric techniques. This was done by melting the coal in a quartz tube attached to the highvacuum inlet system of a research mass spectrometer. The gases observed were composed of C, S, H, O, N, He and Ar atoms. Hydrogen was the most abundant gas; others were helium, methane, ethylene, ethane, carbon monoxide, nitrogen, hydrogen sulphide, propane, argon, carbon dioxide and sulphur dioxide. Gas compositions were found to be a function of the source of the coal. For example, over 65% of the gas from Alabama coal was hydrogen, but West Virginia coal yielded only about 30% of hydrogen. All coals released about 100 cm 3 g −1 (STP) (about 2300 ft 3 (short ton) −1 ) of combustible gas. An additional observation was the fact that about 90% of the sulphur was physically separated from the coal in the vacuum melting process.