Fluorescence of the Bivalent Rare Earths

Przibram, Karl

doi:10.1038/139329b0

Cited by 17 publications

(4 citation statements)

References 2 publications

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“…Rare earth ions like europium, samarium, terbium, etc. can be introduced into the alkali halide lattices, either in trivalent or divalent form and their presence in either form has been confirmed [7] by means of optical absorption studies. The trivalent form occurs when the crystal is grown from aqueous solutions composed of respective halides.…”

Section: Optical Absorptionmentioning

confidence: 83%

Optical absorption, photoluminescence, and thermally stimulated luminescence of CsCl: Tb crystals

Selvan

Selvasekarapandian

Neelamegam

1996

Physica Status Solidi (b)

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Optical absorption, photoluminescence, and thermoluminescence emission studies are made on CsCI:Tb3' crystals at room temperature. The presence of impurities is confirmed by the characteristic OA band at 360 nm. Photoluminescence of these crystals shows characteristic Tb3+ emissions due to transitions from the 5D3 and 5D4 levels to various levels of the 'F septet. The glow curve studies clearly show the participation of terbium ions in the thennoluminescence process. The new 415 K glow peak, not observed in pure CsCl, is ascribed to the terbium ion in the vicinity of F centers. All the TL glow peaks give the characteristic emissions of Th'+ in addition to the emission due to the recombination of the F electron with V-type centers.

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Section: Optical Absorptionmentioning

confidence: 83%

Optical absorption, photoluminescence, and thermally stimulated luminescence of CsCl: Tb crystals

Selvan

Selvasekarapandian

Neelamegam

1996

Physica Status Solidi (b)

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“…Once the mass is melted and single crystals are grown, only the bivalent form appears to be present. According to Przibram [18] the reduction of Eu3+ to Eu2+ occurs if alkali halides which have crystallized with traces of europium are heated to temperature above 200 "C. These results have further been confirmed by Gruen It was shown elsewhere [9] that in undoped NaCl crystals two glow peaks, one around 65 "C and other around 180 "C, are observed. The nature of these peaks is well understood.…”

Section: Discussionmentioning

confidence: 64%

“…The presence of either form is confirmed by optical ahsorption and fluorescence measurements. The trivalent form occurs when an alkali halide crystal is grown from aqueous solutions composed of alkali halides and rare earth halides [18]. It will also occur if the dry mixture of two salts is pulverized and pressed presumed t o form a pellet.…”

Section: Discussionmentioning

confidence: 99%

Thermoluminescence and optical absorption studies of Z1-centres in NaCl crystals doped with samarium

Reddy

Rao

Babu

1982

phys. stat. sol. (a)

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Thermal annealing of X‐irradiation induced point defects in samariuni doped NaCl crystals is investigated by thermoluminescence and optical absorption methods. The results of the influence of pre‐heat treatment and optical bleaching on the glow curves and the production of Z1‐centres are discussed. The glow curve of a NaCl crystal containing I mol% samarium shows four peaks around 60, 90, 130, and 180°C (T1, T2, T3, and T4 peaks, respectively). Quenching the crystal from higher temperatures results in the enhancement of the T3 and T4 peaks and suppression of T2 peak. Bleaching of X‐irradiated crystal with F‐light shows that the T3 peak is enhanced whereas the T1 and T4 peaks get suppressed and the T2 peak is completely suppressed. Optical absorption studies of the crystal before and after F‐bleaching shows that the F‐band decreases and the decrease is accompanied by a broadening towards longer wavelengths. Annealing studies of the X‐irradiated crystal at room temperature show that the T1 and T2 peaks correspond to shallow traps. The T3 peak is attributed to Z1 centres and T4 peak to F‐centres. These studies confirm the formation of Z1‐centres in samarium doped NaCl crystals and the dependence of glow curves on the state of dispersion of the impurity.

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“…The luminescence of fluorite, the mineral in which fluorescence was first recognized, is still the subject of much discussion, but most of its luminescence is now attributed to rare-earth activators. Although rare-earth activators are usually in a trivalent state, the europium, samarium, and ytterbium activators in many fluorites have been reduced by radioactivity to a divalent state with resultant changes in .the emission band frequencies (Przibram, 1937). The important luminescence of scheelite and powellite results from the tungstate and molybdate ions (Cannon and Murata, 1944), but Servigne (1938Servigne ( , 1939Servigne ( , and 1940 has shown that in addition to this tungstate luminescence the emission spectra of most scheelites show rare-earth lines which extend into the infrared region.…”

Section: Important Activators For Infrared Luminescencementioning

confidence: 99%

Infrared luminescence of minerals

Barnes¹

1958

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Infrared luminescence is a phenomenon similar to fluorescence under ultraviolet light except that the emission occurs in the infrared rather than the visible part of the spectrum. This infrared luminescence is generally most efficiently excited by visible light from high-energy incandescent lamps, but violet and ultraviolet excitation are effective for a few minerals. Infrared luminescence can be viewed through an infrared image tube of the type used in the "snooperscope." The entire study collection of the U. S. National Museum has been examined with an image tube and optical system of a snooperscope to detect the infrared luminescence of minerals. Infrared luminescence was found in about 1,500 specimens representing some 75 distinct mineral species. Filters were used to determine the approximate wavelengths of emission and excitation. Chromium-activated minerals like corundum, beryl, spinel, jadeite, and kyanite show very strong infrared luminescence. Cadmium causes the universal luminescence of its sulfide, greenockite. The rare earths are responsible for the long-wavelength emissions of many minerals including scheelite, fluorite, apatite, feldspar, and amphibole.

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Fluorescence of the Bivalent Rare Earths

Cited by 17 publications

References 2 publications

Optical absorption, photoluminescence, and thermally stimulated luminescence of CsCl: Tb crystals

Optical absorption, photoluminescence, and thermally stimulated luminescence of CsCl: Tb crystals

Thermoluminescence and optical absorption studies of Z1-centres in NaCl crystals doped with samarium

Infrared luminescence of minerals

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