Effusion technique

Vapor pressures of phases in these systems were measured by the Knudsen effusion technique. Use of mass spectrometer-target collection apparatus to perform thermodynamic studies is discussed. The prominent sublimation reactions for these phases below 2000 K was shown to involve formation of elemental plutonium vapor. Thermodynamic properties determined in this study were correlated with corresponding values obtained from theoretical predictions and from previous measurements on analogous intermetallics. 

Vapor pressures were determined by using the Knudsen effusion technique. Effusion rates through and orifice contained in each sample cell were measured as a function of temperature by use of a mass spectrometer/target collection... 

Knudsen effusion technique and equation, vapor pressure determination. 100-101... 

Using the Knudsen effusion technique and highly purified samples of lindane [(y-HCH), one of the most widely used and most frequently detected organochlorine pesticides see Willet et al. (1998)], Boehncke et al. (1996) determined the vapor... 

Excellent agreement was obtained with several earlier measurements using the Knudson effusion technique (Ref 65). The vapor pressure of liq TNT has been measured up to 143° with the Knudsen procedure (Ref 19) the following equation was obtained ... 

Knudsen-effusion technique, extrapolated from 37-54.92°C, Smith et al. 1964)... 

Metals. Kruglikh, et al. (104) measured saturated vapor pressures of erbium, samarium, and ytterbium by the Knudsen effusion method, and standard (average) sublimation entropies of 18.4, 20.7, and 25.6 cal./(gram atom °K.) were derived. Nesmeyanov, et al. (146) studied the vapor pressure of yttrium by an integral variant of the effusion technique. Similar studies at higher temperatures by Herrick (70) on samarium metal have been interpreted in good accord by both first and second law methods. Ideal gas thermodynamic functions have been derived from 100 °K. to 6000°K. at 100° intervals for both actinide and lanthanide elements by Feber and Herrick (45). 

The congruent vaporization of LaS has been studied over the range 2012°-2490°K. using the effusion technique with the aid of a vacuum balance and a mass spectrometer by Cater, et al. 23). 

The goal was to determine vapor pressures of tars cycle-by-cycle, where between each cycle, certain amounts of higher volatility species were evaporated. As the effusion technique built in this laboratory was best suited for measuring vapor pressures from lO" to 10 torr, the temperature had to be continuously increased as more and more volatile species were lost in the process. The process is further complicated by the fact that pyrolysis tars generally have a tendency to age wifli time, especially, at higher temperatures. It is known that condensation/polymerization type reactions become considerably facile at temperatures above 100 °C. 

Equilibrium studies of vapor pressure over LiA102(cr) by the torsion effusion technique support the adopted value of... 

Peterson and Hutchison (1 ) used a weight loss Knudsen effusion technique to observe vapor pressures of the liquid at 18 temperatures ranging from 1076 K to 1294 K. Our 2nd and 3rd law analyses of these data, after rejection of one point due to... 

Peterson and Hutchison (1, used a weight loss Knudsen effusion technique to observe vapor pressures of the liquid at 20... 

The total pressure of the vapour in equilibrium with (3-SnSe was measured in the temperature range 862 to 920 K using the Knudsen effusion technique. The enthalpy and entropy of sublimation according to the reaction a-SnSe SnSe(g) were calculated by the review from the reported vapour pressure expression and the selected heat capacities of SnSe(g) and a-SnSe, the enthalpy of transformation a-SnSe —> (3-SnSe being 1.28 kJ-mof (cf V.7.4.1.2), and a heat capacity expression of (3-SnSe being identical to that of a-SnSe, yielding (SnSe, a, 298.15 K) = (188.2 + 20.0) kJ-mol and... 

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