FAR INFRARED ELECTRONIC TRANSITION IN TYSONITE RARE-EARTH FLUORIDES

This work was supported in part by the Joint Services Electronics Program (Contract DA28-043-AMC 02536(E)), by a NASA Grant NGR22-009-(237) and by the U.S. Air Force (ESD Contract AF 19(628)-6066). Present address of R.P. Lowndes and C.H. Perry: Dept. of Physics, Northeastern University, Boston, Mass. 02115.