Potential of mass spectrometry for the analysis of inorganic high-temperature vapors.

Abstract

Mass spectrometry is the most versatile method for the analysis of high-temperature vapors, because it enables the identification of the gaseous species and the determination of their partial pressures. If the vaporization processes are conducted under thermodynamic equilibrium, thermodynamic data can be evaluated from the partial pressures and their temperature-dependencies. The mass spectrometric methods used for the determination of thermodynamic data of high-temperature vapors are Knudsen effusion mass spectrometry (KEMS), transpiration mass spectrometry (TMS), and laser-induced vaporization mass spectrometry (LVMS). KEMS is used whenever possible. Limitations of KEMS and TMS are the container problem, which limits the measurement temperatures to approximately 2500 K. The container problem is overcome by LVMS, which enables measurements up to approximately 7,000 K. The upper limit of the partial pressure measurement by KEMS of approximately 10 Pa does not apply for TMS, which enables measurements up to pressures of approximately 0.1 MPa. The fundamentals of the different methods are described and results are presented. Emphasis is on KEMS.