Conversion of F₃⁺ Centers and Destruction of R Centers in LiF with R Light

R₁ and R₂ bleaches of irradiated LiF near 300°K have revealed the existence of a new color center whose main absorption band covers the region of the R₁ and R₂ bands. The new center is not related to any of the known color centers, and facilitates the conversion of F₃⁺ centers into R centers according to the mechanism F₃⁺+e→R, where the electron is provided by the photo-ionization of the new color center by the R bleach. Simultaneously, but at a slower rate, the R bleach also destroys the R centers by two concurrent mechanisms: (a) decomposition of an R center into an M center and an F center, and (b) conversion of an R center into another color center whose absorption band (550 mμ) is in the N-band region. If an N band in LiF is to be identified with the 550-mμ band, the present work favors a rearranged F₃ model for the N center over the current Pick model of an F₄ complex.