James C. Carver

An ESCA study of organosilicon compounds

Abstract The silicon 2p electron binding energies have been measured for a series of 33 organosilicon compounds. The binding energies are correlated with partial atomic charges calculated by various electronegativity models and CNDO calculations. Group shifts are reported for various chemical groups attached to silicon and are found to correlate with group shifts reported for carbon and phosphorus compounds.

Devaluation of the gold standard in x-ray photoelectron spectroscopy

Abstract The value of vapor-deposited gold as a standard in x-ray photo-electron spectroscopy has been studied. During the deposition gold may react with the sample giving consequent shifts and/or broadening of the Au 4f peaks. Shifts to higher binding energies have been observed with KCN and NACl and to lower energies with Na 2 S 2 O 3 and copper phthalocyanine. The An 4f peaks have been investigated over the temperature range −50 to 200°C. At higher temperatures peaks due to metallic gold are observed. Anomalous effects have been observed in the XPS spectrum of gold plated copper phthalocyanine in the binding energy range 650–950 eV.

Studies of Polymeric Bond Failure on Aluminum Surfaces by X-ray Photoelectron Spectroscopy (ESCA)

X-ray photoelectron spectroscopy (ESCA) has been used to identify very thin layers of polymeric species remaining on aluminum plates after the polymer was cured and stripped from the aluminum. Two polymers were studied. In one, the residual polymeric carbon was used as the tracing signal; in the other, the polymeric silicon was used. In both cases, the polymeric species was partially sputtered from the aluminum surface by an argon ion gun. A reduction in the polymeric signal relative to a standard signal was noted. The results of this study show that, when the polymers studied were mechanically pulled from the aluminum substrate, the failure was a cohesive separation within the polymer, rather than failure at the polymer-aluminum interface. Scanning electron microscopy was used to show that the residual polymer does not remain on the surface as “clumps” or “islands,” but rather as a smooth surface a few atomic layers thick.

X-ray photoelecton spectroscopic (ESCA) study of 1,2-bis(diphenyl-phosphino)-ethane, 1-(diphenylphosphino)-2-(dimethylamino)-ethane and related compounds

Abstract ESCA spectra for compounds of the type φ 2 P-CH 2 CH 2 -Pφ 2 , φ 2 PCHCHPφ 2 , φPCCPφ 2 and, Me 2 NCH 2 CH 2 Pφ 2 are reported along with similar compounds having positive charges on one or both of the heteroatoms. For uncharged molecules, group electronegatives correlated with P (2 p ) binding energies. For molecules having a charged site, the inductive effect of the charged atom was a major factor determining binding energies for both heteroatoms. Among similar compound types, anion effects were absent. For molecules containing nitrogen, the smaller (CH 3 ) 2 N-group allowed anion shielding of the positive charge, causing smaller shifts than for similar compounds containing only phosphorus. Correlations between charge, calculated from Sanderson electronegatives, and P (2 p ) and N (1 s ) binding energies are reported.

An Esca Study of Intermediate Oxidation States in Cobalt-Mol Ybdenum-Alumina Catalysts

Abstract Changes in the oxidation states of molybdenum in a Co-Mo-alumina catalyst are reported as a function of reduction time. Mo(VI), Mo(V) and Mo(IV) were seen, but not Mo(III). Reduction of the catalyst is necessary for thiophene desulfurization. Sulfiding of the catalyst in H2S/H2 showed conversion to MoS2. Use of H2S/H2 also produced sulfiding of the cobalt.