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Creation of groups of spatially correlated excitations in wide‐gap solids
Author(s) -
Kirm Marco,
Lushchik Aleksandr,
Lushchik Cheslav
Publication year - 2005
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200460150
Subject(s) - alkali metal , exciton , chemistry , trihalide , halide , ion , excited state , quantum yield , absorption edge , atomic physics , crystal (programming language) , luminescence , valence (chemistry) , valence electron , electron , excitation , crystallography , band gap , fluorescence , materials science , inorganic chemistry , condensed matter physics , physics , optoelectronics , organic chemistry , quantum mechanics , computer science , programming language
Processes of efficient creation of groups of electronic excitations (EEs) or defects have been considered for radiation‐sensitive (alkali halides) and radiation‐resistant (metal oxides) single crystals. In MgO, pure or doped with Be 2+ , Ca 2+ and Al 3+ ions, the 7.63 eV edge emission of anion excitons is efficiently excited at 10 K in a wide region of 30–90 eV. Multiplication process with the creation of secondary electron–hole pairs and the decay process of cation excitations are compared in crystals of two types: (i) KCl, KBr and LiF, where anion excitons and valence holes undergo self‐trapping and (ii) a MgO crystal, where no self‐trapping of excitations occurs. In alkali halides, a group of spatially correlated EEs, formed at photon absorption, is transformed into an F–I–V K triplet of defects at 5 K or into a temperature‐stable F centre and a trihalide molecule (e.g., Br 3 – ) at 295 K. In BaMgAl 10 O 17 :Eu at 295 K, the 2.72 eV emission of Eu 2+ centres with quantum yield of 1.1–3.5 at the excitation by photons of 13–30 eV has been obtained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)