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RISS 인기검색어
- 검색키워드
- 저자 : Mahlik, S (검색결과 4 건)
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Luminescence of LiBaF<sub>3</sub> and KMgF<sub>3</sub> doped with Eu<sup>2+</sup>
Mahlik, S.,Wisniewski, K.,Grinberg, M.,Seo, H.J. North-Holland 2010 Journal of non-crystalline solids Vol.356 No.37
In this contribution the results of the high pressure spectroscopy of LiBaF<SUB>3</SUB> and KMgF<SUB>3</SUB> doped with Eu<SUP>2+</SUP>, where high pressure was applied in a diamond anvil cell are summarized. Photoluminescence, time resolved luminescence and luminescence kinetics, at a pressure from ambient to 300kbar, at 77K and ambient temperature are shown and discussed. The LiBaF<SUB>3</SUB>:Eu<SUP>2+</SUP> luminescence spectra consisted of sharp lines peaked at 27,500-28,000cm<SUP>-1</SUP> attributed to the <SUP>6</SUP>P<SUB>7/2</SUB>-><SUP>8</SUP>S<SUB>7/2</SUB> transitions in the 4f<SUP>7</SUP> electronic configuration of Eu<SUP>2+</SUP> and a broad band extended between and 21,000 and 26,600cm<SUP>-1</SUP>, attributed to Eu<SUP>2+</SUP> trapped exciton recombination. When the pressure increased the Eu<SUP>2+</SUP> trapped exciton emission disappeared and was replaced by a sharper band peaked at 28,200cm<SUP>-1</SUP> attributed to 4f<SUP>6</SUP>5d<SUP>1</SUP>(e<SUB>g</SUB>)->4f<SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition in Eu<SUP>2+</SUP>. The KMgF<SUB>3</SUB>:Eu<SUP>2+</SUP> luminescence contained only the sharp lines related to the <SUP>6</SUP>P<SUB>7/2</SUB>-><SUP>8</SUP>S<SUB>7/2</SUB> transition of Eu<SUP>2+</SUP> and was found to be pressure independent, up to 300kbar. The differences in the emission spectra between LiBaF<SUB>3</SUB>:Eu<SUP>2+</SUP> and KMgF<SUB>3</SUB>:Eu<SUP>2+</SUP> are discussed in the context of the structure of Eu<SUP>2+</SUP> sites in perovskite and inversed perovskite lattices.
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Pressure evolution of LiBaF<sub>3</sub>:Eu<sup>2+</sup> luminescence
Mahlik, S,Grinberg, M,Shi, Liang,Seo, Hyo Jin IOP Pub 2009 Journal of Physics, Condensed Matter Vol.21 No.23
<P>We investigated the single crystals of LiBaF3 doped with Eu2+ using high pressure spectroscopy, where high pressure was applied in a diamond anvil cell. Photoluminescence, time-resolved luminescence and luminescence kinetics at pressures from ambient to 200 kbar and at temperatures from 10 K to ambient were studied. At ambient conditions the luminescence spectra consisted of sharp lines peaked at 360 nm attributed to the P-6(7/2) --> S-8(7/2) transitions in the 4f(7) electronic configuration of Eu2+ (the zero-phonon line and five single-phonon repetitions) and a broad band extending between 375 and 475 nm attributed to Eu2+ trapped exciton recombination. When pressure was increased the Eu2+ trapped exciton emission disappears and was replaced by the sharper band peaked at 355 nm, attributed to the 4f(6)5d(1)(eg). 4f(7)(S-8(7/2)) transition in Eu2+. To analyze the pressure dependence of luminescence spectra a model of impurity trapped excitons was developed. At temperatures lower than 50 K only the sharp lines related to P-6(7/2) --> S-8(7/2) transitions were observed for all pressures considered. Analysis of low temperature spectra allowed us to estimate the energies of the fifth phonon modes and the values of the Gruneisen parameters.</P>
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New Eu<sup>2 + </sup> sites in KMgF<sub>3</sub>:Eu<sup>2 + </sup> crystal
Grinberg, M,Mahlik, S,Wisniewski, K,Seo, Hyo Jin IOP Pub 2011 Journal of Physics, Condensed Matter Vol.23 No.3
<P>The luminescence properties of KMgF<SUB>3</SUB>:Eu<SUP>2 + </SUP> are investigated at different pressures in the temperature range 25–292 K. Five new Eu<SUP>2 + </SUP> luminescence (NEL) lines due to the <img SRC='http://ej.iop.org/images/0953-8984/23/3/035404/cm371366ieqn1.gif' ALIGN='MIDDLE' ALT='^{6}\mathrm {P}_{7 / 2} \to {}^{8}\mathrm {S}_{7 / 2} '/> transition are identified at 362.49 nm (L<SUB>1</SUB>), 362.53 nm (L<SUB>2</SUB>), 360.72 nm (L<SUB>3</SUB>), 360.15 nm (L<SUB>4</SUB>) and 359.59 nm (L<SUB>5</SUB>) together with the line at 359.32 nm (L<SUB>0</SUB>) which is well known in KMgF<SUB>3</SUB>:Eu<SUP>2 + </SUP>. The emission lines under excitation at 325 nm show a strong dependence on temperature. At 25 K the emission spectrum consists of only two sharp lines, L<SUB>1</SUB> and L<SUB>2</SUB>. Three additional lines (L<SUB>3</SUB>, L<SUB>4</SUB> and L<SUB>5</SUB>) begin to appear with increasing temperature. With a further increase in temperature from 150 to 292 K all the lines disappear except for the single sharp line at 359.32 nm (L<SUB>0</SUB>). The zero-phonon transition of line L<SUB>0</SUB> is accompanied by vibronic sidebands. A pressure shift of five NELs is estimated to be about − 0.6 cm<SUP> − 1</SUP> kbar<SUP> − 1</SUP> similarly to the shift of line L<SUB>0</SUB>, while the lifetimes of the NELs are about 0.7 ms which is shorter than that (5.2 ms) of L<SUB>0</SUB> at 80 K. The new luminescence lines are attributed to the Eu<SUP>2 + </SUP> ions occupying the K<SUP> + </SUP> sites with fluorine vacancy (F<SUP> − </SUP> center) complexes. </P>
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Barzowska, Justyna,Lesniewski, Tadeusz,Mahlik, Sebastian,Seo, Hyo Jin,Grinberg, Marek Elsevier 2018 Optical materials Vol.84 No.-
<P><B>Abstract</B></P> <P>We present an optical pressure sensor KMgF<SUB>3</SUB>:Eu<SUP>2+</SUP> suitable for experiments in diamond anvil cell (DAC), which we have calibrated against the ruby reference sensor at pressures ranging from atmospheric up to 30 GPa (300 kbar), at room temperature. The emission spectra of KMgF<SUB>3</SUB>:Eu<SUP>2+</SUP> consist of one prominent emission line related to the <SUP>6</SUP>P<SUB>7/2</SUB> → <SUP>8</SUP>S<SUB>7/2</SUB> electronic transition (zero phonon line) accompanied by weak phonon sidebands. The energy of emission at atmospheric pressure was determined to be 27846 ± 7 cm<SUP>−1</SUP>. The edge of the excitation spectrum lies at wavelength around 325 nm (30800 cm<SUP>−1</SUP>) making it suitable to excite with He-Cd laser (325 nm). The sensor exhibits linear pressure shift of rate equal to −0.815 ± 0.007 cm<SUP>−1</SUP>/kbar at pressures up to 300 kbar. The pressure shift of the emission is totally reversible and the pressure sensor is suitable for multi cycle pressure experiments. The sensor's exceptional feature is that excitation and emission spectra lie in near UV, which makes it very convenient to use in high pressure optical measurements in visible and IR region with no interference from the sensor's luminescence.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New optical pressure sensor for high pressure experiments – KMgF<SUB>3</SUB>:Eu<SUP>2+</SUP>. </LI> <LI> Sensor has been callibrated for pressures up to 300 kbar (30 GPa). </LI> <LI> Pressure sensor is applicable at cryogenic temperatures as well as above room temperature. </LI> <LI> Luminescence in UV range prevents interference of the sensor during high pressure optical measurements in VIS-IR range. </LI> </UL> </P>
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