Complex molecules in cesium-rare earth iodide vapors

The optical absorption of the vapors above neodymium iodide and cerium iodide were studied: (1) individually, (2) in combination with cesium iodide, and (3) in combination with cesium iodide and mercury between 600 and 1100°C. Changes in the spectra show that a stable complex molecule CsI · NdI3 is formed that increases the amount of Nd vaporized. A similar enhancement of the vaporization of Ce appears to occur with the cerium plus cesium iodide system, but no changes in absorption structure were found. At high mercury pressure a weak complex between Hg and CsI · NdI3 apparently forms. Vapor pressures and thermodynamic quantities have been deduced from the data.