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91.
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
92.
Emel Kalfao?luBünyamin Karabulut 《Journal of magnetism and magnetic materials》2012,324(8):1593-1595
The molecular orbital coefficients and the EPR parameters of trisodium citrate dihydrate, sodium hydrogen oxalate monohydrate, potassium d-gluconate monohydrate and L-Alanine vanadyl complexes are calculated theoretically. Two d-d transition spectra and EPR parameters for the VO2+ complex are calculated theoretically by using crystal-field theory. The calculated g and A paramaters have indicated that paramagnetic center is axially symmetric. Having the relations of g∥〈g⊥〈ge and A∥〉A⊥ for VO2+ ions, it can be concluded that VO2+ ions are located in distorted octahedral sites (C4v) elongated along the z-axis and the ground state of the paramagnetic electron is dxy. 相似文献
93.
Structural features and properties of a series of hafnium iron phosphate glasses have been investigated by Mössbauer spectroscopy and X-ray diffraction. Mössbauer spectra indicate that all of the glasses contain both Fe(II) and Fe(III) ions. The isomer shift values obtained from the Mössbauer fits show that both Fe(II) and Fe(III) ions are in octahedral or distorted octahedral coordination. The crystalline HfP2O7 phase was detected in all the samples by powder X-ray diffraction but this did not degrade the chemical durability of the glasses as the dissolution rates of the glasses are comparable to that of base iron phosphate glass. 相似文献
94.
O. Karabulut M. Parlak R. Turan U. Serincan B. G. Aknolu 《Crystal Research and Technology》2006,41(3):243-249
The structure and temperature dependent spectral photoconductivity of as‐grown and N‐and Si‐implanted GaSe single crystals have been studied. It was observed that post‐annealing results in a complete recovery of the crystalline nature that was moderately reduced upon implantation. The band edge is shifted in the implanted sample which is attributed to the structural modifications and continuous shallow levels introduced upon implantation and annealing. Our calculations showed that the trap density is increased upon implantation and annealing which confirms a possibility of explanation the phenomenon within a framework of continuous trap levels. Photocurrent measurements as a function of photo‐excitation intensity also support continuous distribution of localized states in the band gap. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
95.
In the present study, the potential of rectangular fins with 30° and 90° angle and 10 mm offset from the horizontal direction for heat transfer enhancement in a plate fin heat exchanger is numerically evaluated with conjugated heat transfer approach. The rectangular fins are mounted on the flat plate channel. The numerical computations are performed by solving a steady, three-dimensional Navier–Stokes equation and an energy equation by using Fluent software program. Air is taken as working fluid. The study is carried out at Re = 400 and inlet temperatures, velocities of cold and hot air are fixed as 300, 600 K and 1.338, 0.69 m/s, respectively. Colburn factor j versus Re design data is presented by using Fluent. The results show that the heat transfer is increased by 10 % at the exit of channel with fin angle of 30° when compared to channel without fin for counter flow. The heat transfer enhancement with fins of 30° and 90° for different values of Reynolds number with 300, 500 and 800 and for varying fin heights, fin intervals and also temperature distributions of fluids on the top and bottom surface of the channel are investigated for parallel and counter flow. 相似文献
96.
97.
H. Paşaoĝlu B. Karabulut G. Kaştaş R. Tapramaz A. Karadaĝ 《Applied magnetic resonance》2006,30(1):75-83
Electron paramagnetic resonance of Cu2+-doped catena-trans-bis(N-(2-hydroxyethyl)-ethylenediamine) zinc(II)-tetra-μ-cyanonicelate(II) [Zn(NH2(CH2)3NHOH)2Ni(CN)4] single crystals and powder are examined at room temperature. The spectra show the substitution of the Zn2+ ion with the Cu2+ ion. The crystal field around the Cu2+ ion is nearly axial. There is a single paramagnetic site withg
xx=2.073,g
yy=2.060,g
zz=2.248,A
xx=40.5 G,A
yy=50.8 G,A
zz=172.0 G. The ground-state wave function is an admixture of d
x
2−y
2 and d
z
2 states. The optical-absorption studies show two bands at 320 nm (31250 cm−1) and 614 nm (16286 cm−1) which confirm the axial symmetry. The crystal field parameters and the wave function are determined. 相似文献
98.
The ring‐opening metathesis polymerization of cyclododecene using an electrochemically reduced tungsten‐based catalyst (WCl6? e?? Al? CH2Cl2) is described. In addition, the influence of reaction conditions on the polymerization yield was determined. The resulting polymer has been characterized by NMR, IR, gel permeation chromatography and differential scanning calorimetry. The glass transition temperature and melting point of the polydodecenamer are 19.6°C and 70.0°C respectively. Furthermore, cyclododecene has been polymerized into a low‐molecular‐weight polymer (12.0 × 103) with a polydispersity of 2.06 in high yields (94%). IR and NMR analysis indicate that the polydodecenamer has a high trans content (60%). Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
99.
100.
Rahmi Dumlupinar Faruk Demir Abdulhalik Karabulut Halil Karakurt 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,103(2):331-339
In this study, bean seedlings (Phaseolus vulgaris cv. Gina 2004) were exposed to chilling temperatures until leaves are wrinkled (9 day), that is, showed nyctinastic movement. Pulvinus were subsequently were cut from the leaves. Concentrations of inorganic elements (P, S, Cl, K, Ca, Cu) in the pulvinus were measured by wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry. Results indicated that concentration change (%) was not significant for Ca (0.82) but it was significant for K, P, Cl, S, and especially Cu concentrations (5.4%, 12.8%, 40.2%, 43.7%, 365%, respectively) in pulvinus of plants exposed to chilling temperature compared with control group.We hypothesize here the presence of association between nyctinasti movement brought about by pulvinus at chilling temperature in bean and changes of K, P, Cl, S and especially Cu concentrations measured by WDXRF analysis method. 相似文献