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Jahn‐Teller Effect and Partially Covalent Bond as Causes of Low Symmetry of Ga + , In + , and Tl + Centres in CsCl‐Type Alkali Halides
Author(s) -
Zazubovich S. G.
Publication year - 1970
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19700380109
Subject(s) - alkali metal , halide , excited state , tetragonal crystal system , covalent bond , chemistry , crystallography , ion , luminescence , activator (genetics) , atomic physics , crystal structure , inorganic chemistry , physics , biochemistry , optoelectronics , organic chemistry , gene
Partially polarized luminescence is observed for Ga + , In + , and Tl + centres in alkali halides of CsCl‐type structure at liquid nitrogen temperature. The symmetry of excited Ga + , In + , and Tl + centres is established to be tetragonal in the most crystals investigated. The symmetry of Tl + centres in CsI:Tl crystals is trigonal. The possible causes of the low symmetry are discussed. The interaction of the optical electrons of the activator with tetragonal vibrations of the lattice may be the main cause for the low symmetry of the excited Ga + , In + , and Tl + centres in most of the alkali halides. The partial covalent bond between thallium and some of the surrounding iodine ions seems to be essential for CsI:Tl crystals.