[en] Xenon is separated from a mixture of xenon and krypton by extractive distillation using carbon tetrafluoride as the partitioning agent. Krypton is flushed out of the distillation column with CF₄ in the gaseous overhead stream while purified xenon is recovered from the liquid bottoms. The distillation is conducted at about atmospheric pressure or at subatmospheric pressure

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[en] Partial photoelectron cross sections sigma and angular distribution parameters β were obtained for the first five valence orbitals in CF₄: 1t₁, 4t₂, 1e, 3t₂, and 4a₁, as a function of photon energy from 17 to 70 eV. These data were taken with the aid of angle-resolved photoelectron spectroscopy and synchrotron radiation. The results were compared with earlier data on CCl₄. Substantial differences were found. These are explained partly in terms of the absence of a Cooper minimum with a fluorine compound as opposed to the presence of a Cooper minimum with chlorine compounds and partly in terms of the position of shape resonances. Data on CF₄ were also compared with recent calculations of Stephens et al., who used the multiple-scattering Xα method. Structure in the photoelectron spectrum of CF₄ lying on the low energy side of the third band was identified as due to autoionization and evidence is given as to its specific nature

[en] The morphology of single crystal silicon and SiO₂ surfaces etched in CF₄ or CF₄ + 5% O₂ plasma as well as properties of MOS structures obtained by thermal oxidation of plasma etched Si are studied. The etched surfaces are rough and the shape and the size of the roughnesses depend mainly on the thickness of the removed layer and are different for Si and SiO₂. The electrical properties of MOS structures fabricated on plasma etched Si surfaces can not be distinguished from those of reference samples, prepared on standard cleaned Si wafers. (author)

[en] Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 ev and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 ev, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 ev where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of e/p (Pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient e/p ranges as compared with conventional gas mixtures

[en] The infrared spectra of the ¹²C, ¹³C, and ¹⁴C isotopic species of CF₄ have been observed at a resolution of 0.06 cm^-1. In addition to the fundamentals ν₃ and ν₄ a number of combination bands have been observed. Using these results, combined with Raman data in the literature, we have calculated the quadratic valence force field, in terms of force constants as well as compliance constants, with considerably better precision than previously obtained. Interaction displacement coordinates have been calculated and show that stretching one CF bond leads, for minimum energy near equilibrium, to opening up of the angles between the other three bonds as well as to their contraction

[en] Using semi-empirical quantum chemical approximation methods (EHMO, CNDO) and the cluster model of solid surface, elementary steps of plasma etching are discussed within the system halogen radical metal surface. For some metals (V. and VIII. subgroup, aluminium) a reaction mechanism is suggested using the balloon effect. (author)

[en] The apparent inertness of pure CF₄ in ionizing radiation disappears when CF₄ is mixed with other substances which can react with fluorine atoms, radicals, and ions produced by radiolysis. Studies of the time dependence of the composition of CF₄ + C mixtures in ionizing radiation show that both the amounts and maximum size of volatile perfluoralkanes larger than CF₄ increase with exposure in the ionizing radiation of a nuclear reactor. The ratio of material not volatile at 25⁰C increases and the ratio of CF₄ remaining decreases with exposure