LUMINESCENCE FOR F CENTERS IN CALCIUM OXIDE

This paper reports data on the luminescence spectra associated with F and F+ centers in calcium oxide. Irradiation in the F band excites emission bands at 500 and 627 nm, which we identify with the transitions P1→S1 and P3→S1, respectively, of the F center. Radiative-lifetime measurements are consistent with this assignment. It is suggested that the weakness of the 500-nm band relative to the 627-nm band is due to competition between the P1→S1 transition and a radiationless decay from the P1 to the P3 level. At 4.2 K, well-resolved fine structure is observed on the high-energy side of both the 627-nm band and the 369.7-nm (F+) band. For both bands, the phonon-assisted structure can be reconstructed using only three vibrational modes. © 1969 The American Physical Society.