Total pressure

About: Total pressure is a research topic. Over the lifetime, 5199 publications have been published within this topic receiving 66658 citations.

Electron attachment to the perfluoroalkanes n‐CNF2N+2 (N=1–6) using high pressure swarm techniques

Abstract: The electron attachment rate constants and negative ion formation mechanisms for six perfluoroalkanes [n‐CNF2N+2(N=1–6)] have been studied in a high pressure swarm experiment within the mean electron energy range from thermal energy (≊0.04 eV) to ≊4.9 eV. These experiments were performed over a total gas number density range of 3.2×1019 to 3.9×1020 cm−3 using N2 and argon as buffer gases. Dissociative electron attachment was found to be the only negative ion formation process for CF4 and C2F6. For C3F8, n‐C4F10, and n‐C5F12 the electron attachment rate constant measurements exhibited a large total pressure dependence which was strongest for C3F8 and decreased with increasing size of the perfluoroalkane molecule. These measurements have been interpreted as electron attachment by parent negative ion formation due to three‐body stabilization processes of the initially excited, short‐lived (5×10−11 s <τ<10−8 s) parent anion. The lifetimes of these transient parent anions have been found to depend on the natur...

Quantitative Infrared Intensity Measurements. I. Carbon Monoxide Pressurized with Infrared‐Inactive Gases

Abstract: Quantitative infrared intensity measurements on CO pressurized with H2, He, A, O2, and N2 for total pressures up to 700 psia have been carried out The values of integrated absorption for the fundamental and first overtone of CO have been found to be 237 cm−2 atmos−1 and 164 cm−2 atmos−1, respectively The numerical values of integrated absorption were obtained by using an indirect method for the interpretation of experimental data, similar to the extrapolation technique of Wilson and WellsThe experimental data obtained at very large values of the total pressure should yield correctly the numerical values of the spectral absorption coefficients This statement is supported by the fact that the integral over the spectral absorption coefficients at a total pressure of 700 psia yields values for the integrated absorption of fundamental and first overtone of CO which are in excellent agreement with results obtained by indirect methods

Mass Spectrometric Identification of Si–O–H(g) Species from the Reaction of Silica with Water Vapor at Atmospheric Pressure

Abstract: A high-pressure sampling mass spectrometer was used to detect the volatile species formed from SiO2 at temperatures between 1200C and 1400C in a flowing water vapor/oxygen gas mixture at 1 bar total pressure. The primary vapor species identified was Si(OH)4. The fragment ion Si(OH)3+,' was observed in quantities 3 to 5 times larger than the parent ion Si(OH)4+. The Si(OH)3+ intensity was found to have a small temperature dependence and to increase with the water vapor partial pressure as expected. In addition, SiO(OH)+ believed to be a fragment of SiO(OH)2, was observed. These mass spectral results were compared to the behavior of silicon halides.

Kinetics and mechanism of the silane decomposition

Abstract: The homogeneous gas-phase decomposition kinetics of silane has been investigated using the single-pulse shock tube comparative rate technique (T = 1035–1184˚K, Ptotal ≈ 4000 Torr) The initial reaction of the decomposition SiH4 SiH2 + H2 is a unimolecular process in its pressure fall-off regime with experimental Arrhenius parameters of logk1 (sec−1) = 1333 ± 028–52,700 ± 1400/2303RT The decomposition has also been studied at lower temperatures by conventional methods The results confirm the total pressure effect, indicate a small but not negligible extent of induced reaction, and show that the decomposition is first order in silane at constant total pressures RRKM-pressure fall-off calculations for four different transition-state models are reported, and good agreement with all the data is obtained with a model whose high-pressure parameters are logA1 (sec−1) = 155, E1(∞) = 569 kcal, and ΔE0±0(1) = 559 kcal The mechanism of the decomposition is discussed, and it is concluded that hydrogen atoms are not involved It is further suggested that silylene in the pure silane pyrolysis ultimately reacts with itself to give hydrogen: 2SiH2 → (Si2H4)* → (SiH3SiH)* → Si2H2 + H2 The mechanism of H ⟷ D exchange absorbed in the pyrolysis of SiD4-hydrocarbon systems is also discussed