A‐Type Centres in KBr:Na

Topa, V.; Matei, Lidia; Serban, T.

doi:10.1002/pssb.19630031130

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…I n a previous paper [9] we have shown that in electrolytically coloured NaCl:(Ag + Ca) crystals the B-band has a shoulder which we called B,-band.…”

Section: X-irradiated Crystals At R O O M Temperaturementioning

confidence: 91%

“…The influence of various concentrations of Ag and Ca ions upon the induced absorption bands was followed in crystals with the same concentration of Ag but different amounts of Ca. Simultaneous introduction of Ag and Ca was performed in order to obtain V-type centres due to an enhancement of positive ion vacancies and, a t the same time, to produce absorption bands associated with centres including both Ag and Ca as in [9].…”

Section: Introductionmentioning

confidence: 99%

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Colour Centres in X‐Irradiated NaCl:Ag and NaCl:(Ag + Ca) Crystals

Topa

Haragea

1966

Physica Status Solidi (b)

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A study is made of colour centres induced by X-irradiation a t room temperature in NaC1:Ag and NaCl: (Ag + Ca). It is shown that the induced bands in NaCl: Ag are strongly dependent on the concentration of Ag as well as on the irradiation time and also that the B-, C-, and D-bands have a complex structure. Three components of the B-band, four of the C-band and two of the D-band are found at liquid nitrogen temperature. Optical bleaching in the F-light shows that only a component of the B-, C-, and D-bands is definitely electronic. It is also noted that only the optical bleaching of the F-band in NaC1:Ag results in a simple B-band much like that obtained by electrolytic colouring. The incorporation of both Ca and Ag in NaCl and subsequent X-irradiation lead t o very intensive B-and Dbands which are shifted t o shorter wavelengths compared with those bands in crystals containing only Ag. The optical bleaching experiments on these crystals suggest that colour centres containing both Ca and Ag are probably formed, as in the case of similar crystals electrolytically coloured.In NaCl: Ag und NaCl: (Ag + Ca) werden Untersuchungen an Farbzentren durchgefuhrt, die durch Rontgenbestrahlung bei Zimmertemperatur erzeugt werden. Die induzierten Banden in NaCl werden stark von der Ag-Konzentration und der Bestrahlungsdauer beein-fluBt, und die B-, Cund D-Banden zeigen eine komplizierte Struktur. Drei Komponenten der B-Bande, vier der C-Bande und zwei der D-Bande werden bei der Temperatur des fliissigen Stickstoffs gefunden. Optisches Bleichen im F-Licht zeigt, da13 nur eine Komponente der B-, Cund D-Banden eindeutig elektronisch ist. Auch fiihrt nur optisches Bleichen der F-Bande in NaCl: Ag zu einer einfachen B-Bande genau nie bei elektrolytischer Verfiirbung. Der Einbeu von Ce und Ag in NaCl mit darauffolgender Rontgenbestrahlung ergibt intensive B-und D-Banden, die im Vergleich zu Kristallen, die nur Ag enthalten, nach kiirzeren Wellenliingen verschoben sind. Die Experimente an diesen Kristallen weisen darauf hin, daB hauptsachlich Farbzentren gebildet werden, die sowohl Ca als auch Ag enthalten, wie im Falle ahnlicher Kristalle, die elektrolytisch verfarbt werden.

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“…I n a previous paper [9] we have shown that in electrolytically coloured NaCl:(Ag + Ca) crystals the B-band has a shoulder which we called B,-band.…”

Section: X-irradiated Crystals At R O O M Temperaturementioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Colour Centres in X‐Irradiated NaCl:Ag and NaCl:(Ag + Ca) Crystals

Topa

Haragea

1966

Physica Status Solidi (b)

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New Exciton Bands in KJ:Na Crystals Containing A‐Centres

Topa

Matei

Serban

1965

Physica Status Solidi (b)

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Type A‐centres are found in KJ:Na single crystals. The conversion F → A is followed in the visible region and near the fundamental absorption edge. The intensity of the β‐band decreases with the formation of A‐centres and at the same time a new band (βA) is formed at longer wavelengths. The disappearance of A‐centres results in a broad Ac‐band in the visible region which is accompanied by the formation of an αA‐band in the ultra violet region, at wavelengths shorter than those corresponding to the α‐band. As the intensities of the A1‐and βA‐bands are proportional the occurrence of the βA‐ and αA‐bands can be explained qualitatively by exciton formation near A‐centres or vacancies which are due to negative ions with a Na ion as nearest neighbour.

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A‐Type Centres in KBr:Na

Cited by 2 publications

References 4 publications

Colour Centres in X‐Irradiated NaCl:Ag and NaCl:(Ag + Ca) Crystals

Colour Centres in X‐Irradiated NaCl:Ag and NaCl:(Ag + Ca) Crystals

New Exciton Bands in KJ:Na Crystals Containing A‐Centres

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