Vacuum out gassing

The sensitivity of our (S+Au)-sensitized emulsions was increased by vacuum outgassing, and the low intensity reciprocity failure was nearly eliminated (108). When the vacuum out-gassed emulsion was equilibrated with water vapor before exposure, sensitivity decreased to a minimum at 40-60% RH, then increased at higher RH, unlike the behavior of emulsions with other types of sensitization where sensitivity continued to decrease. The cause of the increase at high humidities is uncertain. One possibility is that incorporation of gold into the latent image takes place more readily at the high humidities. 

ASTSM D2651-01 - Standard Guide for Preparation of Space product assurance - Thermal vacuum out gassing... 

The choice of metals for vacuum walls is largely based on the ease of fabrication of the metal, machining, cleaning (26), welding, etc. Aluminum alloys are the material of choice for out-gassing at room temperature. 

Manometers were eventually used as measurement devices. By the 1770s, mercury was boiled to increase measurement accuracy. Thus, albeit crudely, both out-gassing and baking out of a vacuum system were instigated. 

Photocatalytic reaction was carried out in a vessel connected with a closed gas circulation system equipped with vacuum line and sampling tube for the analysis of evolved gases. The photocatalytic activity was evaluated by the O2 evolution from AgNOs aqueous solution, where the photoproduced electron reduces Ag+ and the positive hole oxidize OH" in the solution to O2. The prepared photocatalyst was suspended in the well out-gassed AgNOs solution... 

In the vacuum metallizing processes, out-gassing results in parts that show voids or thin spots in plating with reduced and spotty brilliance. Out-gassing can also cause fogging of optical components near to the plastic part. 

Question NASA has asked us to model a transient out-gassing problem for a thin plastic plate containing a volatile substance that will gradually effuse from the plate over time when exposed to the vacuum of space. Obtain an approximate expression for the time it takes for the concentration of this substance to decrease to 1/10 of its initial value at the mid point of the plate upon exposure to the space vacuum. Assume that at time t = 0 exposure to the space vacuum fixes c = 0 on the two faces of the plate, while the initial concentration of the species inside the plate starts at a uniform value of c° and the plate has a thickness of L. 

Amounts and type of oxygen complexes formed during oxidation, as well as their thermal stabilities, were evaluated by TPD under helium. Porosity in all carbons (previously out-gassed at 250 °C) was characterized by carbon dioxide adsorption at 273 and 289 K, and CH4, O2 and N2 adsorptions at 298 K (for molecular sieve studies). Heats of immersion into dichloromethane, for carbons outgassed at 250 °C under vacuum, were determined at 30 °C. Finally, the separation abilities of the different CMSs were evaluated by determining the adsorption kinetics of CO2, CH4, N2 and O2 at 298 K. 

The enthalpies of immersion of the carbons into hexane and 1-hexene were determined at 303 K in a Tian-Calvet type differential mioxx orimeter (Setaram, C80D). Prior to the experiments, the samples (0.1 g) were out-gassed under vacuum at 523 and 773 K for 4 h, as describai previously [10],... 

Table 3 reports the enthalpy of immersion (-AHi, J g ) of the carbons in hexane and in 1-hexene at 303 K, after out-gassing under vacuum at 523 and 773 K for 4 h. The areal enthalpies (mJ m ) calculated taking into account the sinface area obtained for N2 adsorption are also reported. For all the samples, the enthalpy of immersion in 1-hexene is higher than in hexane. Comparing the areal en alpies of immersion in the two liquids, the values increase with the degree of strength of oxidation. 

Microcalorimetric measurements of propylene adsorption in the oxidized carbons treated at 1073 K under He and under H2 are plotted in Fijg. 5. For the samples treated under He, the initial heats of adsorption are 64 and 58 kJ-mof for CMS-HNO3 and CMS-H2O2, respectively. For the samples treated under H2, the initial heats of adsorption are 53 kJ-mof for both carbons. The samples treated in H2 have a weaken adsorption strength of propylene, while samples treated in He give the same results than when out-gassed at 527 and 773 K under vacuum. 

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