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221.
Mustafa İlhan Mete Kaan Ekmekçi Ayhan Mergen Cemalettin Yaman 《Journal of fluorescence》2016,26(5):1671-1678
Undoped and Eu3+ doped BaTa2O6 phosphors were synthesized via solid state reaction method and characterized by using XRD, SEM-EDS and photoluminescence (PL) analyses. The XRD results revealed that the crystal structure of BaTa2O6 allowed up to 10 mol% levels of Eu3+ ions due to the TTB characteristic network of adjacent octahedrals. SEM-EDS analyses confirmed the formation of BaTa2O6 structure and EuTaO4 secondary phase. BaTa2O6:Eu3+ phosphors exhibited orange and red emissions at 592.2 nm and 615.7 nm in the visible region respectively. The Commission Internationale d’Eclairage (CIE) chromaticity coordinates of the BaTa2O6:Eu3+ phosphors that excited at λ ex = 400 nm ranged from orangish-red to pinkish-red depending on increasing Eu3+ concentration. 相似文献
222.
We consider the model theory of the real and complex fieldswith a multiplicative group having the Mann property. Amongthese groups are the finitely generated multiplicative groupsin these fields. As a by-product we obtain some results on groupswith the Mann property in rings of Witt vectors and in fieldsof positive characteristic.k 2000 Mathematics Subject Classification03C10, 03C35, 03C60, 03C64, 03C98, 13K05. 相似文献
223.
We study a service facility modelled as a single-server queueing system with Poisson arrivals and limited or unlimited buffer size. In systems with unlimited buffer size, the service times have general distributions, whereas in finite buffered systems service times are exponentially distributed. Arriving customers enter if there is room in the facility and if they are willing to pay the posted price. The same price is charged to all customers at all times (static pricing). The service provider is charged a holding cost proportional to the time that the customers spend in the system. We demonstrate that there is a unique optimal price that maximizes the long-run average profit per unit time. We also investigate how optimal prices vary as system parameters change. Finally, we consider buffer size as an additional decision variable and show that there is an optimal buffer size level that maximizes profit. 相似文献
224.
Mustafa Yüksek Hüseyin Ertap Ayhan Elmali H. Gul Yaglioglu Gasan M. Mamedov Mevlüt Karabulut Mustafa K. Öztürk 《Optics & Laser Technology》2012,44(7):2178-2181
We have investigated the structural and optical properties of bulk GaTe crystal grown by vertical Bridgman method. Two photon absorption (TPA) properties of GaTe crystal have been investigated by the open aperture Z-scan technique under 1064 nm wavelength with 4 ns or 65 ps pulse durations. The TPA coefficients are greater in ns regime than that of ps regime. Upon increasing intensity of incident light from 5.02×107 W/cm2 to 1.07×108 W/cm2, the TPA coefficients increased from 3.47×10?6 cm/W to 8.53×10?6 cm/W for nanosecond excitation. Similarly, when intensity of incident light was increased from 6.81×108 W/cm2 to 9.94×108 W/cm2 the TPA coefficients increased from 3.53×10?7 cm/W to 6.83×10?7 cm/W for picosecond excitation. Measured TPA coefficient of GaTe crystal is larger than that of GaSe and GaS layered crystals. 相似文献
225.
Dr. Kepeng Chen Ivan V. Kurganskii Xue Zhang Prof. Ayhan Elmali Prof. Jianzhang Zhao Dr. Ahmet Karatay Prof. Matvey V. Fedin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(27):7572-7587
Anthracene-naphthalimide (An-NI) compact electron donor-acceptor dyads were prepared, in which the orientation and distance between the two subunits were varied by direct connection or with intervening phenyl linker. Efficient intersystem crossing (ISC) and long triplet state lifetime (ΦΔ=92 %, τT=438 μs) were observed for the directly connected dyads showing a perpendicular geometry (81°). This efficient spin-orbit charge transfer ISC (SOCT-ISC) takes 376 fs, inhibits the direct charge recombination (CR) to ground state (1CT→S0, takes 3.04 ns). Interestingly, efficient SOCT-ISC for dyads with intervening phenyl linker (ΦΔ=40 % in DCM) was also observed, although the electron donor and acceptor adopt almost coplanar geometry (dihedral angle: 15°). Time-resolved electron paramagnetic resonance (TREPR) spectroscopy shows that the electron spin polarization of the triplet state, i. e. the electron spin selectivity of ISC, is highly dependent on the dihedral angle and the linker. For the dyads showing weaker coupling between the donor and acceptors, the charge separation and the intramolecular triplet energy transfer are inhibited at 80 K (frozen solution), because both the 3An and 3NI states were observed and the ESP are same as compared to the native anthracene and naphthalimide, which unravel their origin. The dyads were used as triplet photosensitizers for triplet−triplet annihilation upconversion (TTA UC). High UC quantum yield (ΦUC=12.9 %) as well as a large anti-Stokes shift (0.72 eV) was attained by excitation into the CT absorption band. 相似文献
226.