Roswell F. Pottie

Equilibrium vapour concentrations of some polycyclic aromatic hydrocarbons, As4O6 and SeO2 and the collection efficiencies of these air pollutants

Abstract The saturated or equilibrium vapour concentrations of the following inorganic substances and polycyclic aromatic hydrocarbons are reported: SeO 2 , As 4 O 6 , pyrene, B(a)A, B(a)P, B(e)P, B(k)F, B(ghi)P and coronene. The significance of these results with respect to the efficacy of collection of these pollutants on particulate filters and the validity of the previous measurements of collection efficiency are considered in detail. The conclusion is that significant losses may be expected for some of these compounds (As 4 O 6 , SeO 2 , pyrene and B(a)A), that the efficacy of collection is subject to considerable question for some others [B(a)P, B(e)P and B(k)F] although losses may be minimized by adsorption effects, and that for others still [B(ghi)P, coronene] losses should be insignificant.

Vapour pressures of arsenic over InAs(c) and GaAs(c). The enthalpies of formation of InAs(c) and GaAs(c)

Abstract The equilibrium vapour pressures of arsenic over InAs(c) and GaAs(c) have been studied using the Knudsen-cell mass-spectrometric technique. Appropriate corrections were made for the solubility of arsenic in the liquid metals Ga and In which were produced in the decomposition. The following enthalpies of decomposition were derived: 2 GaAs(c)=2Ga(c)+As 2 (g); δH°(298.15 K)=(89.7±1.2) kcal th mol −1 ; 2 InAs(c)=2In(c)+As 2 (g); δH°(298.15 K)=(77.7±1.2) kcal th mol −1 ; The errors assigned are estimates of total error. Enthalpies of formation of GaAs(c) and InAs(c) were also derived. From measurements of the partial pressures of both As2 and As4 over InAs(c), the enthalpy of dissociation of As4 was also determined. As 1 (g)=2As 2 (g); δH°(298.15 K)=(54.4±1.5) kcal th mol −1 . This is in excellent agreement with the result obtained previously when MoAs2(c) and Mo2As3(c) were used as sources.

Discrimination in electron multipliers for atomic ions 1. Multiplier yields for 24 mass-analyzed ions☆

Abstract Electron multiplier yields have been measured for 24 atomic ions in an Atlas CH-4 mass spectrometer. The ions were generated by electron impact on appropriate parent compounds, and the yields were normalized to that for argon. The multiplier was of the Allen type with Cu-Be dynodes, and the total ion energy was 5.1 keV. The multiplier yields decreased with increasing mass for elements within a Periodic Group, and for different groups, the general trend of the yields was: IIIA

Hydrogen evolution in fused quartz ampoules

Using a mass spectrometer it has been shown that up to 4×10−6 litres at s.t.p. of hydrogen per cm2 of surface are irreversibly evolved in evacuated fused quartz ampoules at 1300K after normal degassing. Fused quartz of various types and from various sources has been tested for this effect. The contribution of this gas evolution to sample contamination during phase preparation, annealing, etc. is discussed. A thermal pretreatment procedure which reduces the hydrogen evolution by approximately a factor of forty has been devised.