Beschreibung:
<jats:title>Abstract</jats:title><jats:p>ESR and infrared absorption are measured on neutron‐irradiated LiF:OH crystals. In unirradiated specimens an sharp absorption at 2.8 μ;m is observed and attributed to OH<jats:sup>−</jats:sup> ions coupled to a Mg impurity. After neutron irradiation the 2.8 μm band disappears and a broad band appears at 1930 cm<jats:sup>−1</jats:sup>. When the irradiated crystal is annealed at higher temperatures, the 1930 cm<jats:sup>−1</jats:sup> band increases a little and then decreases. In parallel with the decay of the 1930 cm<jats:sup>−1</jats:sup> band, another absorption band grows peaking at 1013 cm<jats:sup>−1</jats:sup>, which is attributed to U centers in LiF. H<jats:sup>0</jats:sup> centers are observed by ESR in neutron‐irradiated crystals. On annealing at higher temperatures the H<jats:sup>0</jats:sup> centers increase as the 1013 cm<jats:sup>−1</jats:sup> band grows. While the 1013 cm<jats:sup>−1</jats:sup> band increases monotonously with temperature, the H<jats:sup>0</jats:sup> centers decrease above 270 °C. It is concluded that hydrogen centres are produced by dissociation of OH‐ ions in neutron‐irradiated LiF:OH crystals and that immediately after irradiation U centers do not exist, which are formed in the course of annealing from the precursor suggested to be U<jats:sub>1</jats:sub> centers and afterwards from H<jats:sup>0</jats:sup> centers.</jats:p>