Calibration of vacuum systems by gas quantities

Dobrozemsky, R.

doi:10.1016/0042-207x(90)94192-s

Cited by 16 publications

(7 citation statements)

References 7 publications

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“…The following gases have been calculated to be present using the computer program SGAP (Dobrozemsky, 1972): H 2 O, H 2 , CH 4 , C 2 H 6 , C 3 H 8 , CO, CO 2 , N 2 , H 2 S and SO 2 . Artificial gas mixtures of known compositions were used for calibration (Dobrozemsky, 1990).…”

Section: Methodsmentioning

confidence: 99%

The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization

Saleh

2006

Chin. J. of Geochem.

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The podiform chromitites occur in a well-preserved mantle sequence consisting of lherzolite-harzburgite with abundant lenses of olivine dunite. The podiform chromitite deposits are common as small and irregularly shaped masses in the Southeastern Desert (SED) of Egypt. The podiform chromitites exhibit a wide range of compositions from high Cr to high Al varieties. The Cr of chrome spinel ranges from 0.67 to 0.88 in olivine-dunite, quite similar to that of the high-Cr chromitite, whereas it is around 0.62 in lherzolite-harzburgite. Primary hydrous mineral inclusions, amphibole and phlogopite, in chrome spinel have been reported for the first time from the Pan-African Proterozoic podiform chromitites. On the other hand, petrographic and geochemical evidence suggests that podiform chromitites in the SED of Egypt were formed as a result of crystallization of mafic melts, probably of boninitic composition, the boninitic parental magmas were probably produced by a second stage of melting above a subduction zone. Three types of chromite ores can be distinguished within the SED of Egypt: (a) sulphide-poor podiform ores; (b) brecciated ores; and (c) sulphide-rich ores. Two textural types of inclusions in chromite are distinguished: (1) primary silicate inclusions generally have high Mg-number (>96), Cr and Ni, and are dominated by pargasitic amphibole, forsterite, diopside, enstatite and Na-phlogopite. A diversity of primary and secondary platinum group minerals (PGM) is described from the chromitites, including alloys, sulphides, sulpharsenides and arsenides of Ru, Os, Ir, Rh, Ni, Cu, Fe and Co; (2) in addition to primary PGM and hydrous silicates, the fluids are of low to moderate salinity, sodium-dominated aqueous solutions with complex gas contents. Variable amounts of water, hydrogen, hydrocarbons, carbon dioxides and nitrogen have been determined in inclusion-rich samples. The chondritenormalized PGE patterns of lherzolite-harzburgite and olivine-dunite have negative Ir and Pt, and positive Pd and Au anomalies. Chromitites are homo-geneous in composition but texturally zoned on a large scale. They carry elevated IPGE, manifested in numerous, primary and secondary PGM phases.

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Section: Methodsmentioning

confidence: 99%

The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization

Saleh

2006

Chin. J. of Geochem.

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“…13 The common idea of all these methods is to achieve higher accuracy in the total quantities by comparing the mass spectrometer reading with the reading of a pressure gage. 7 However, such a calibration is not possible for unstable species such as radicals. There is no way to an absolute calibration for them, although approximate estimates may be obtained from a comparison with similar stable molecules.…”

Section: The Likelihoodmentioning

confidence: 99%

“…The actual value of i must be determined by calibrating the quadrupole mass spectrometer. Several different pathways are mentioned in the literature, namely the gas expansion from a calibrated volume, 7 the flash filament method 12 or the gas-injection method. 13 The common idea of all these methods is to achieve higher accuracy in the total quantities by comparing the mass spectrometer reading with the reading of a pressure gage.…”

Section: The Likelihoodmentioning

confidence: 99%

Analysis of multicomponent mass spectra applying Bayesian probability theory

et al. 2001

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In this paper we develop a method for the decomposition of mass spectra of gas mixtures, together with the relevant calibration measurements. The method is based on Bayesian probability theory. Given a set of spectra, the algorithm returns the relative concentrations and the associated margin of confidence for each component of the mixture. In addition to the concentrations, such a data set enables the derivation of improved values of the cracking coefficients of all contributing species, even for those components for which the set does not contain a calibration measurement. This latter feature also allows one to analyze mixtures that contain radicals in addition to stable molecules. As an example, we analyze and discuss the mass spectra obtained from the pyrolysis of azomethane, which contain the radical CH3 apart from nitrogen and C1- and C2-hydrocarbons.

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“…In the throughput method, the total quantity of gas evolved from a sample is determined from the integrated time-dependent pressure change in the apparatus due to outgassing of the sample. Similar techniques (also referred to as gas-burst methods) have been applied for the calibration of vacuum instruments, 4 for the determination of water outgassing from a stainless steel chamber, 5 for the calibration of getter pumps, 6 and for the determination of water coverage on technical surfaces. 7 In the present work, data from the throughput method is modeled to determine D H2O and the total gas desorbed.…”

Section: Introductionmentioning

confidence: 99%

Gas uptake of 3D printed acrylonitrile butadiene styrene using a vacuum apparatus designed for absorption and desorption studies

Sefa

Ahmed

Fedchak

et al. 2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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We describe a vacuum apparatus for determining the outgassing rate into vacuum, the diffusion coefficient, and the amount of gas absorbed for various materials. The diffusion coefficient is determined from a model applied to time-dependent desorption data taken using a throughput method. We used this method to determine the diffusion coefficient, D, for H2O in 3-D printed acrylonitrile butadiene styrene (ABS). We found DH2O = 8.3 × 10−8 cm2/s ± 1.3 × 10−8 cm2/s (k = 1; 67% confidence interval) at 23.2 °C. This result was compared to the diffusion coefficient determined another by a gravimetric method, in which the sample weight was monitored as it absorbed gas from the atmosphere. The two methods agreed to within 3%, which is well within the uncertainty of the measurement. We also found that at least 80% of the atmospheric gas (air) absorbed by the ABS is water. The total amount of all atmospheric gas absorbed by ABS was about 0.35% by weight when exposed to ambient air in the laboratory, which was at a pressure of 101 kPa with a relative humidity of 57% at 22.2 °C.

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Calibration of vacuum systems by gas quantities

Cited by 16 publications

References 7 publications

The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization

The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization

Analysis of multicomponent mass spectra applying Bayesian probability theory

Gas uptake of 3D printed acrylonitrile butadiene styrene using a vacuum apparatus designed for absorption and desorption studies

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