MOLECULAR COMPOSITION AND THERMOCHEMISTRY OF TIN(II), LEAD(II), AND SCANDIUM(III) IODIDE VAPORS

The vaporization of tin(II), lead(II), and scandium(III) iodide was studied by high-temperature mass spectrometry with a Knudsen cell. The monomer and dimer molecules (SnI2)i(g), (PbI2)i(g), and (ScI3)i(g) (i = 1,2) were identified. Enthalpies and entropies of dimerization, equilibrium partial pressures as well as enthalpies and entropies of sublimation were evaluated for the gaseous molecules. Their molecular parameters and the thermodynamic functions computed from them are given. Appearance potentials were determined for the various ions observed upon vaporizing the three different metal iodides