Knudsen Effusion Mass Spectrometry for Study of Vaporization Chemistry

The Knudsen effusion mass spectrometry (KEMS) made it possible to unravel the mystery of the vapor phases of various systems - by identification and quantification of the vapor species in equilibrium with the condense phases of interest. KEMS also enabled deduction of many thermodynamic quantities pertinent to reactions amongst the constituents of the vapor and/or the condensed phases. Since the advent of KEMS, thousands of vaporization studies have been conducted. Many studies are still being performed mostly to obtain better results or for some specific industrial applications. The basic steps of a KEMS investigation might appear routine, but the vaporization chemistry associated with each system makes every study interesting, especially those studies dealing with condensed phase transitions. We describe here a few KEMS studies which reported the effects attributed to phase transformations in congruently as well as incongruently vaporizing systems.