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Optical Properties of Cu‐Complex Centres in KCl Single Crystals
Author(s) -
Kishishita H.
Publication year - 1973
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.2220550141
Subject(s) - exciton , absorption (acoustics) , absorption band , absorption spectroscopy , materials science , crystal (programming language) , single crystal , wavelength , band gap , doping , analytical chemistry (journal) , chemistry , crystallography , molecular physics , optics , condensed matter physics , optoelectronics , physics , composite material , chromatography , computer science , programming language
Absorption and emission spectra of KCl single crystals doped with various amounts of copper have been investigated a t temperatures from 10 to 300 °K. In highly doped specimens, four new absorption bands appear in wavelength regions longer than the 260 nm absorption band which has been attributed to the lowest transition within a single Cu + centre. These new absorption bands are found at 288 nm (B‐band), 324 nm (C‐band), 373 nm (D 1 ‐band), and 382 nm (D 2 ‐band) a t 77 °K. The B‐band is assigned as a transition in paired Cu centres. The D 1 ‐ and D2‐bands are attributed t o exciton absorptions in CuCl clusters formed in KCI crystals. As these clusters are small in size, the optical properties of excitons in them are slightly different from those in bulk CuCl crystals: (1) the energy positions of exciton absorption peaks are 20 meV higher than those of bulk CuCl excitons, (2) the absorption lines show relatively large width and asymmetric shapes, (3) the Stokes shifts are large, and (4) there are no bound excitons. These results are discussed as the characterirtic feature of excitons due to the small size of a CuCl micro‐crystal.