Impurity-trapped excitons and electron traps in CaF2:Yb2+ and SrF2:Yb2+ probed by transient photoluminescence enhancement

Senanayake, Pubudu S.; Wells, J.‐P. R.; Reid, Michael F.; Berden, Giel; Meijerink, Andries; Reeves, Roger J.

doi:10.1016/j.jlumin.2011.09.043

Cited by 13 publications

(8 citation statements)

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“…We have recently demonstrated that it is possible to study in detail the energy level structure of ITE in CaF 2 :Yb 2þ using a two-color transient photoluminescence enhancement technique 3,4 which is similar to that reported earlier. 5 Our technique uses short-pulsed UV excitation of the interconfigurational f !…”

supporting

confidence: 66%

“…This was interpreted as liberation of electrons from shallow traps that were subsequently captured at the lanthanide sites. 4 Here we report results for MgF 2 crystals doped with divalent ytterbium. The luminescent properties of MgF 2 :Yb 2þ have been reported previously.…”

mentioning

confidence: 93%

“…We have recently demonstrated that it is possible to study in detail the energy level structure of ITE in CaF 2 :Yb 2+ using a two-color transient photoluminescence enhancement technique. 3,4 This technique uses short-pulsed UV excitation of the interconfigurational f → d transitions with subsequent formation of the ITE. The pulsed infrared output of a freeelectron laser (FEL) is spatially overlapped with the UV beam and given a short temporal delay relative to the lifetime of the ITE emitting state(s) i.e.…”

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confidence: 99%

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Electron trap liberation in MgF₂ doped with Yb²⁺ using a two-color excitation experiment

et al. 2012

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We utilize the optical transitions of Yb 2+ excited by an ultraviolet optical parametric amplifier to probe electron trap liberation in MgF 2 via the observation of a photoluminescence enhancement effect induced by a subsequent infrared pulse from a free-electron laser. The temperature dependence of the enhancement suggests that we liberate very shallow traps having a depth of approximately 17 cm −1 . The observed 'trap spectrum' is consistent with a simple model of a Coulomb trap.

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confidence: 66%

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confidence: 93%

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Electron trap liberation in MgF₂ doped with Yb²⁺ using a two-color excitation experiment

et al. 2012

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“…Figure 7 indicates the traps in NaMgF 3 :Yb 2+ have an approximate depth of 800 cm −1 compared to 400 cm −1 in CaF 2 and SrF 2 . 18 At an IR excitation energy above 800 cm −1 the number of ITEs created from trap liberation is almost equal the number created directly by UV excitation. There are clearly many electron traps in NaMgF 3 and traps play an important role in the system's luminescence.…”

Section: Trap Liberationmentioning

confidence: 95%

Site-selective transient photoluminescence enhancement of impurity-trapped excitons in NaMgF3:Yb2+

et al. 2013

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The excited-state structure of impurity-trapped excitons are measured in a multisite system. We use a two-color (UV-IR) pulsed photoluminescence enhancement technique, which probes the interlevel transitions and dynamics of impurity-trapped excitons in doped insulating phosphor materials. The technique is applied to NaMgF 3 :Yb 2+ , which exhibits emission from two charge-compensation centers with peaks at 22300 cm −1 (448 nm) and 24000 cm −1 (417 nm). The observed photoluminescence enhancement is caused by a combination of intraexcitonic excitation and electron trap liberation. The electron traps are inferred to have a depth of approximately 800 cm −1 .

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“…All these issues show that the spectroscopic properties of divalent Ytterbium ions need exact investigation as information on Yb 2+ in melt‐quenched glasses is hard to find. Up to now, spectral properties of Yb 2+ were reported for numerous crystalline phases as eg YAG, MgF 2 , CaF 2 , KMgF 3 and SrAlF 5 , besides many others . For glasses, Yb 2+ has so far mostly been reported in quartz glass which needs very high temperatures for production promoting the partial reduction of Yb 3+ to Yb 2+ .…”

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Spectroscopic properties of Yb²⁺ in aluminosilicate glass

Assadi

Herrmann

Damak

et al. 2017

Int J of Appl Glass Sci

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In contrast to Yb 3+ which is a well-investigated optically active ion, the spectroscopic properties of its divalent counterpart Yb 2+ in glasses are hardly investigated, although Yb 2+ might have a notable influence on the luminescence properties of Yb 3+ -doped glasses even at low Yb 2+ concentrations because of its strong f-d transitions. In this paper, we report on the preparation and spectroscopic properties of Yb 2+ -doped aluminosilicate glasses that were produced using the normal meltquench technique. The glass composition is 20CaOÁ20Al 2 O 3 Á60SiO 2 (mol%). To achieve a sufficient amount of Yb 2+ in the samples, different methods were applied to influence the red-ox equilibrium during glass melting: firstly, under argon atmosphere and additional argon bubbling, and secondly by the addition of metallic aluminum powder to the batch. The strongly reduced samples show a greenish to brownish yellow coloring which could be attributed to the strong absorption of Yb 2+ ions in the UV to blue spectral range. The absolute Yb 2+ concentration in the glass and the molar extinction coefficient of Yb 2+ was obtained by spectroscopic measurements. If irradiated with UV light, the Yb 2+ -doped samples show a broad fluorescence emission in the wavelength range from 450 to 700 nm with a peak at around 515 nm.silicate, optical glasses, aluminosilicate glasses, ytterbium II, photoluminescence | INTRODUCTIONIn contrast to the well-studied Yb 3+ ions, investigations of its lower oxidation state Yb 2+ are hardly reported for melt-quenched glasses. However, Yb 2+ might occur besides the widely used Yb 3+ , and hence information on its optical properties and its red-ox behavior are quite essential. The optically active ion Yb 3+ is used in highpower laser materials, laser fibers and scintillator materials but also as sensitizer for energy transfer and up-conversion processes. 1-3 Recently, the Yb 3+ ion was proposed to improve the solar cell efficiency by utilizing the quantum cutting effect, as it emits close to the efficiency maximum of silicon-based solar cells at around 1000 nm. 4-6 To collect large parts of the solar spectrum, broad band f-d absorption in the UV to blue spectral region is needed. This can for example be achieved by the addition of by Ce 3+ and Eu 2+ . Additionally, the absorption and emission wavelengths of these ions can be tuned to fit the spectral requirements for quantum cutting in connection with Yb 3+ . 7,8 However, the problem in Eu 2+ /Yb 3+ and Ce 3+ / Yb 3+ co-doped materials is the formation of Eu 3+ /Yb 2+ or Ce 4+ /Yb 2+ charge transfer states, which both quench the Eu 2+ or Ce 3+ emissions which is needed for the quantum cutting process. 9,10 To determine whether these charge transfer states are formed, a good knowledge on the spectral properties of Yb 2+ in the host material is required. On the other hand, also the Yb 2+ /Yb 3+ ion pair has been proposed for quantum cutting, since Yb 2+ -as Ce 3+ and Eu 2+ -shows broad and strong absorption in the UV to visible range because of f-d transiti...

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Impurity-trapped excitons and electron traps in CaF2:Yb2+ and SrF2:Yb2+ probed by transient photoluminescence enhancement

Abstract: CaF 2 :Yb 2+ and SrF 2 :Yb 2+ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals.

Cited by 13 publications

References 12 publications

Electron trap liberation in MgF₂ doped with Yb²⁺ using a two-color excitation experiment

Electron trap liberation in MgF₂ doped with Yb²⁺ using a two-color excitation experiment

Site-selective transient photoluminescence enhancement of impurity-trapped excitons in NaMgF3:Yb2+

Spectroscopic properties of Yb²⁺ in aluminosilicate glass

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Impurity-trapped excitons and electron traps in CaF2:Yb2+ and SrF2:Yb2+ probed by transient photoluminescence enhancement

Abstract: CaF 2 :Yb 2+ and SrF 2 :Yb 2+ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals.

Cited by 13 publications

References 12 publications

Electron trap liberation in MgF2 doped with Yb2+ using a two-color excitation experiment

Electron trap liberation in MgF2 doped with Yb2+ using a two-color excitation experiment

Site-selective transient photoluminescence enhancement of impurity-trapped excitons in NaMgF3:Yb2+

Spectroscopic properties of Yb2+ in aluminosilicate glass

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Product

Resources

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Electron trap liberation in MgF₂ doped with Yb²⁺ using a two-color excitation experiment

Electron trap liberation in MgF₂ doped with Yb²⁺ using a two-color excitation experiment

Spectroscopic properties of Yb²⁺ in aluminosilicate glass