The structure of the self-trapped hole in KMgF ₃

Polyhalogen and Polyinterhalogen Anions from Fluorine to Iodine

“…Fluorine is the most electronegative element in the periodic table.W hen inspecting the electrostatic potential of the fluorine molecule ( Figure 6), one can gain the impression that fluorine is unable to act as aLewis acid in ahalogen bond because of its almost zero s-hole,a nd may therefore be unable to form polyhalides.H owever,q uite recently,t his impression was called into question when evidence for the existence of ap entafluorine monoanion, [F 5 ] À ,w as found under cryogenic conditions in matrix-isolation experiments. [24] The difluorine monoanion, [F 2 ] À : Thed ifluorine anion is not ap olyhalogen anion in the classical sense,b ut it is included in this Review for the sake of completeness.The first spectroscopic evidence for the existence of molecular [F 2 ] À anions trapped in ac rystal lattice was obtained in the late 1960s by Hall [50] and Gilliam and Otto, [51] who performed EPR measurements on single crystals of potassium magnesium fluoride (KMgF 3 )a fter X-ray irradiation, [50] and of potassium bifluoride (KHF 2 )a fter bombardment with electrons. [51] The[ F 2 ] À radical anion (V k center) has also been discussed as am obile species involved in the decomposition process of electron-irradiated CaF 2 .…”

EPR Investigations of a Structural Phase Change in RbCaF3, RbCdF3, and TlCdF3

“…In RbCdF3 this center is not thermally destroyed in the cubic phase near T,. Due to the Czv symmetry of this center in the perovskite lattice the EPR spectrum [7,8] Fig. 1 these centers are labelled 5, 6 , 3 , and 1.…”

Induced Absorption Phenomena, Thermoluminescence and Colour Centres in KMgF3, BaLiF3and LiCaAlF6Complex Fluorides

“…There are varying levels of knowledge and understanding of colour centres in the ternary fluorides, which are under study here. KMgF 3 (KMF) has been studied regarding this aspect in the late sixties 8,9) and absorption bands related to F centres (280 nm), F 2 centres (282 nm and 445 nm), F 3 centres (250 nm and 395 nm) and hole V K centres (340 nm) were determined. 10) Thermoluminescence (TSL) and thermally stimulated current (TSC) processes were studied for undoped and doped KMF in a broad temperature range 11) and thermal release of the intrinsic and perturbed V K centres was recognized as a key factor influencing TSL features below room temperature (RT).…”