Spectrophotometric Study of Alkali-Rare Earth Iodide Vapor Complexes and Their Application to HID Arc Lamps

The complex formation of Ndl3-Csl and Cel3-Csl systems and their application to HID lamp development is described. The results of a spectroscopic study indicate that Ndl3 and Cel3 vaporize as stable NdCsl4 and CeCsl4 complexes in Ndl3 + Csl and Cel3 + Csl mixtures. The apparent vapor pressures of Ndl3 Cel3 at 1000 K show enhancement due to the formation of complex molecules. Arc lamps made of these mixtures have higher luminous efficacy than those containing Cel3 or Ndl3 alone.