Halide transport, chemical vapor

The study of gaseous metal halide complexes is of fundamental interest for the chemistry of coordination compounds. In addition, gaseous metal halide species are of practical importance for material science and technical applications. These practical aspects are reported briefly in the recent review by Schafer [425] and in detail in the book by Hastie [428]. The potential of enhanced vapor phase material transport is for example an important practical aspect and has been described in the monograph by Schafer [437]. It is of interest for metal halide lamps, chemical vapor deposition, and metallurgical processes. The practical significance of complexation for metal halide lamps and the experimental methods used in addition to Knudsen effusion mass spectrometry for the study of metal halide vapors are reported in the recent review article by Hilpert [438]. 

In most cases RXi Is a more volatile halide and Is present only as a vapor whereas GXy may be In a condensed or vapor phase depending on the temperature and total pressure of the system. Stoichiometric coefficients and thermodynamic quantities for reaction 1 have been measured using a variety of experimental techniques. Including mass-spectrometry, chemical transport and spectrophotometry. A large number of halide vapor complexes have been reported, and extensive reviews on their systematlcs and thermodynamics of formation are already available (4-9). 

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