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- Thermodynamic Measurements Using the Knudsen Cell Technique
1 0 Introduction to Knudsen Cell Thermodynamic Measurements The Knudsen cell methods is a classic technique for measuring vapor pressures It was first discussed by M Knudsen in his seminal paper on the vapor pressure of Hg in 1909 (Ref 1) Most Knudsen cells are similar to Figure 1, measuring about 1 cm diameter and 1 cm high Basically, a near equilibrium is established between the
- Thermodynamic Activity Measurements with Knudsen Cell Mass Spectrometry
Coupling d until equilibrium is attained between the condensed and vapor phases The vapor s continuously sampled by effusion through a small orifice in the cell A molecular beam is formed from the effusing vapor and directed into a mass spectrometer for ide
- Design and construction of a simple Knudsen Effusion Mass Spectrometer . . .
A tempera-ture controlled Knudsen effusion cell, suitable for controlled generation of a molecular beam of the sample organic com-pounds is coupled to a vacuum chamber, and a quadrupole mass spectrometer to allow direct measurement of vapour pressure, analogous to the KEMS systems used to study the vapour pressure of ceramics (Bencze et al , 2006)
- Development of the Knudsen effusion methodology for vapour pressure . . .
The effect of the improvements on the performance of the Knudsen effusion apparatus was tested and evaluated by the comparison of the vapour pressure results of 1,3,5-triphenylbenzene and 1-ethyl-3-methylimidazolium with the available literature data
- Modern Vapor Pressure Measurements Based on the Knudsen-Effusion
The Knudsen method of molecular effusion is employed successfully to determine small vapor pressures (< 20 mbar) — even at temperatures higher than 1500 K The various techniques are rewiewed briefly Special emphasis is placed (i) on two newer automatic apparatus for pressure measurement by the TORKER-method (Torkometer and Computer-operated dynamic torsion pendulum) as well as (ii) on the
- Vapor pressure determination using a QCM - IOPscience
It employs a Knudsen cell to produce an effusive molecular beam, only a small fraction of which is deposited on a cooled (225 K) quartz crystal microbalance (QCM) Vapor pressure values are derived from the mass gain rate determined by the QCM, Knudsen cell temperature, and fixed geometric factors
- Thermodynamic Measurements Using the Knudsen Cell Technique
The Knudsen cell technique has been used for over a century and is a valuable tool for measurement of vapor pressures and thermodynamic properties It is based on a small enclosure (~1 cm long x 1 cm diameter) in which a condensed phase vapor equilibria can be established
- Measurement of low vapour pressures according to the Knudsen effusion . . .
In particular the thermo-gravimetric vapour pressure measurements by means of a Knudsen cell and a newly developed vapour pressure balance for exact measurement of very low vapour pressures are described Applications for organic materials (fungicides, benzoic acid, oils) are discussed
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