New oxygen centres in KCl single crystals

Abstract

Doping of pure KC1 with oxygen in a closed system leads to formation of a new oxygen containing centre. Absorption, fluorescence, and ESR spectroscopy have been used together with chemical analysis to characterise the centre. It is suggested that the centre is an 02,--anion vacancy association. The radiolysis of the doped KC1 single crystals and the influence of subsequent annealing treatments have been investigated. Die Dotierung von reinem KC1 mit Sauerstoff in einem abgeschlossenen System fiihrt ziir Bildung eines neuen Sauerstoffzentrums. Absorptions-, Fluoreszenz-und ESR-Spektroskopie wurden zusammen mit chemischen Analysenmethoden verwendet, urn das Zentrum zu charakterisieren. Es wird angenommen, daD das Zentrum ein 0;--Anionenluckenassoziat ist. Die Radiolyse von dotierten KC1-Einkristallen und der EinfluD einer darauffolgenden Temperungsbehandlung wurden untersucht.

Nanoporous Crystal 12CaO·7Al2O3: A Playground for Studies of Ultraviolet Optical Absorption of Negative Ions

“…We note that the OH - → CCB transitions with the calculated excitation energy of 5.1 eV can also contribute to the absorption edge shift to lower energies. The assignment of the 5.6 eV band to the transition from OH - to the FCB is consistent with earlier studies of alkali halides: − OH - ions substituting anion sites exhibit absorption bands peaking at 5.6−6.6 eV, which have been assigned to the excitation from the oxygen 2p levels to the conduction bands. In accord with this assignment, the peak position shifts to lower energies for narrower band gap hosts. ,, …”

“…The assignment to the intermolecular transitions is consistent with reported observations that O 2ions exhibit UV absorption bands ascribed to intramolecule transitions of π u f π g when incorporated in alkali halides (5.0 eV) 35,36,39 and inert gas crystals (4.5-5.0 eV). 41 The intramolecular π g f σ* transitions of O 2 2ions also contribute to these bands, because the absorption of the O 2 2ion occurs at 5.0 eV in BaO 2 , and that of the O 2 2--anion vacancy complex is observed at 4.8 eV in alkali halides 37,38 although their intensities are very small. Thus, it is tentatively concluded that the additional absorption bands at ∼4.7 and 4.3 eV in the oxygen radical incorporated C12A7 are attributed to the transitions from the VB to oxygen radicals and/or the intramolecule transitions of O 2and O 2 2-.…”

Communication: Strong excitonic and vibronic effects determine the optical properties of Li2O2

“…The optical spectrum of the O 2 2− ion in the bulk of ionic lattices was investigated in Na 2 O 2 commercial samples by Griffiths et al 7 8 They observed a broadband of width ∼0.5 eV peaking at 4.77 eV in the absorption spectrum and a broadband of width ∼0.3 eV peaking at 3.14 eV in the emission spectrum. This noticeable Stokes shift (1.63 eV) and the broadening of the bands are fingerprints of a strong vibronic coupling rea) Author to whom correspondence should be addressed.…”