The conversion of F-centers to centers giving a broad absorption band at about 700 mμ has been found to be primarily thermal rather than optical. Evidence is presented to show that these centers are higher aggregates of F-centers and lattice vacancies, but are not colloidal. At temperatures between 300 and 500°C the F-centers are in equilibrium with the higher aggregates; the equilibrium was studied as a function of temperature and concentration. Absorption measurements at -195°C show that several species contribute to absorption in the band; some suggestions as to the likely nature of the centers are given.

+More

lattice vacancies fcenters

Allen B. Scott Lamar P. Bupp,.The Equilibrium between F-Centers and Higher Aggregates in KCl. 79 (2),341–346.

Allen B. Scott Lamar P. Bupp,"The Equilibrium between F-Centers and Higher Aggregates in KCl" 79

Allen B. Scott Lamar P. Bupp,"The Equilibrium between F-Centers and Higher Aggregates in KCl"