The M⁺ Center in CaF₂

Abstract

Abstract S‐irradiation of additively colored CaF 2 at low temperature produces two new absorption bands at 545 and 360 nm at the expense of the M band at 519 nm. These same bands can also be produced by ultraviolet bleaching at low temperature of additively colored CaF 2 doped with electron trapping impurities. In addition, excitation into either band gives rise to a luminescence band peaking at 645 nm, and both absorption bands can be reversibly bleached with visible light. We propose that these bands arise from the M + center.