Seongtae Park

Influence of ligands on the photoluminescent properties of Eu3+ in europium β-diketonate/PMMA-doped systems

Abstract Three kinds of europium β-diketonates Eu(DBM) 3 , Eu(BA) 3 and Eu(TTA) 3 (DBM: Dibenzoylmethane; BA: 1-Benzoylacetone; TTA: Thenoyltrifluoroacetone) were doped in poly(methyl methacrylate) (PMMA) matrix. The doped systems were studied by using photoluminescent (PL) spectroscopy, emission decay experiments and X-ray diffractometry. Eu(III) ions in the doped Eu(DBM) 3 /PMMA systems have two distinct symmetric sites and the emission band changes greatly with the compositions. Eu(III) in the Eu(BA) 3 /PMMA systems gives only one symmetric site in the doped systems and the emission band changes slightly with the compositions. Although two distinct symmetric sites of Eu(III) can be distinguished in the doped systems of Eu(TTA) 3 /PMMA, the two sites have similar 5 D 0 lifetimes and the luminescent spectra almost do not change with the compositions. XRD reveals that crystallites were formed in the doped Eu(DBM) 3 /PMMA systems that have different crystalline structure from that of the chelate, and Eu(BA) 3 and Eu(TTA) 3 exist in amorphous state in the doped systems. The difference between the PL properties and structures of the doped systems for the three kinds of chelates should be attributed to different interactions between the chelate molecules and between the chelate and PMMA.

X-ray-induced reduction of Sm3+-doped SrB6O10 and its room temperature optical hole burning

We prepared two kinds of Sm-doped strontium borates. When the samples were prepared in air environment, while the Sm3+ ions doped in strontium tetraborate (STB) were well reduced, the trivalent Sm ions were partially reduced in strontium hexaborate (SHB). The SHB was successfully reduced by subsequent x-ray irradiation (SHBX) and showed a strong Sm2+ emission. The photoluminescence, excitation spectrum and spectral hole burning experiments were conducted for the samples. The crystallographic sites of Sm2+ ions were found to be different in the STB and SHBX. Spectral holes were observed at room temperature in both samples STB and SHBX. The measured hole depths were 24% and 63% in STB and SHBX, respectively. As a result, we could obtain effective and novel hole burning material based on the Sm-doped strontium borates with x-ray-induced reduction.

Luminescence and spectral hole burning of Sm2+ doped in Li2O–SrO–B2O3 glass-ceramics

The Sm(3+)-doped alkali strontium borate glass-ceramics were obtained by heating of the as-made glasses in air, where Sm(3+) ions were reduced to Sm(2+) ions. The XRD, optical absorption spectra and luminescence of Sm(3+) and Sm(2+) ions were investigated. The excitation spectra of the (7)F(0)-->(5)D(0) transition were measured in the region of (7)F(0)-->(5)D(1) transition, where spectral holes were burnt within two of the Stark split (5)D(1) bands. The Sm(2+) ions doped glass ceramics exhibit the persistent spectral hole burning at room temperature. The hole depth, which are burned by the DCM dye laser, are about 40% of the total intensity, respectively. It is concluded that the dominant burning mechanism is a photoionization of electron trapping at a site other than Sm(3+) ions because of the absence of an antihole around the burned hole.

The influence of metal aluminium on the reduction of the Sm3+ doped in aluminosilicate glass films

Sm3+-doped glass sol was prepared by a sol–gel method and coated on a bare Si substrate and an Al coated Si substrate (Al/Si). The coated glass films were heat treated in a hydrogen atmosphere or air to reduce the Sm3+ to Sm2+ and then the optical properties were examined through a photoluminescence (PL) experiment. While the glass films coated on a bare Si substrate or an Al/Si one were well reduced in hydrogen atmosphere, only the glass films coated on the Al/Si substrate were reduced in air. We thus suggest two possible reducing mechanisms related to hydrogen and the metal aluminium and we found that the metal aluminium coated on a Si substrate plays an important role in the reducing process.

Axion dark matter search with the storage ring EDM method

We propose using a modified storage ring EDM method to search for the axion dark matter induced EDM oscillation in nucleons. The method uses a combination of B and E-fields to produce a resonance between the

Development of position sensitive radiation detectors using gas electron multipliers

g-2

Realization of Spin-dependent p-C Scattering in GEANT4 and Its Application To Storage Ring Experiment For pEDM

precession frequency and the background axion field oscillation to greatly enhance the sensitivity to it. An axion frequency range of 100Hz to 100MHz can be scanned with large sensitivity, corresponding to

On LBNE neutrino flux systematic uncertainties

f_a

Photoluminescent behaviors of several kinds of europium ternary complexes doped in PMMA

range of

Reduction effect on the optical properties of Sm2+ doped in SrB4O7 and SrB6O10 crystals

10^{13}