Bayrakçeken, Fuat

Article | 2007 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy68 ( 1 ) , pp.143 - 146

The 12B2 › 32B2 transition in the absorption spectrum of the benzyl free radical has been recorded in the vapor phase together with a new band at shorter wavelengths, probably the first Rydberg band of the radical in the vapor phase. The photolysis flash was of short duration and it was possible to follow the kinetics of the radicals' decay, which occurred predominantly by bimolecular recombination. © 2006 Elsevier B.V. All rights reserved.

Bayrakçeken, Fuat | Yaman, A. | Hayvali, M.

Article | 2005 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy61 ( 5 ) , pp.983 - 987

An ultraviolet light-induced photophysical and Photochemical changes of coumarin-481 in cyclohexane have been studied by photolysis technique at room temperature, due to its potential applications in photonics, photochemistry, and electronic spectroscopy. During the optical pumping, coumarin-481 showed photochemical changes, therefore as the concentration of coumarin-481 decreased, a photoproduct concentration increased rapidly. An absorption band of the product was observed at around 250 nm. Photoproduct emission spectra characteristics show that photoproduct molecules can also be used as a laser-dye at different emission frequency . . .. © 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az

Keskin, S.S. | Aslan, N. | Bayrakçeken, Fuat

Article | 2009 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy72 ( 2 ) , pp.254 - 259

Structure elucidation of Coumarin-500 Laser-dye in cyclohexane at room temperature has been studied by UV-Vis, Raman, and FTIR spectroscopic techniques. Optical properties and chemical behavior under the influence of atmospheric positive electric pulsed corona discharges were also examined. The effects of UV-Vis irradiation changed some optical parameters, such as decrease in optical density on the absorption spectrum and formation of photoproducts, due to the chromaticity removal. No significant optical changes were observed in the light absorption upon UV-irradiation but large changes in absorption spectrum were observed after pos . . .itive electric corona discharge treatments, FTIR and Raman spectra in non-polar solvent are recorded and interpreted. © 2008 Elsevier B.V. All rights reserved Daha fazlası Daha az

Bayrakçeken, Fuat

Article | 2009 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy71 ( 5 ) , pp.2026 - 2029

Photophysical and photochemical properties of diradical in the first excited state is recorded for the very first time with the IR, band structure for dianilino molecule at room temperature, in the vapor phase. In this experiment high resolution absorption spectra of anilino free radical, dianilino, aniline in the vapor phase and silicon dioxide in the solid state were recorded by flash photolysis technique photographically. Silicon dioxide absorption band between 250 and 255 nm were also observed for the reaction cell, because the cell and windows of the cell material were spectrosilica grade fused quartz. And this absorption band . . .also used as wavelength calibration for all the photoproducts formed in the reaction cell during optical pumping. © 2008 Daha fazlası Daha az

Bayrakçeken, Fuat

Article | 2004 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy60 ( 4 ) , pp.923 - 925

Ultraviolet light induced high resolution optical absorption spectra and resonance fluorescence of spectroscopically pure fused silica have been studied, due to its potential applications in optoelectronics and flash (laser flash spectroscopy laboratory use), for optical fibers and power optics and lasers. An ultraviolet discrete absorption spectra and resonance coherent fluorescence were recorded photographically between 200 and 260 nm. Resonance discrete and coherent fluorescence were observed at 250-255 and 220-225 nm bands at room temperature by flash photolysis technique. © 2003 Published by Elsevier B.V.

Bayrakçeken, Fuat

Article | 2004 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy60 ( 13 ) , pp.3033 - 3036

High resolution S0 › Sn and T1 › Tn electronic absorptions and B-type delayed fluorescence of 1,2,7,8-dibenzanthracene in polymethylmethacrylate (PMMA) were experimentally observed by flash and laser flash photolysis technique. Dibenzanthracene molecules were excited in a two-step process. In the first step, an excited singlet is created, which undergoes intersystem crossing to triplet state, then T-T absorption creates an excited triplet dibenzanthracene molecule, which returns to the first excited singlet level by intersystem crossing. The re-created first excited singlet of dibenzanthracene decays back to the ground state by emit . . .ting B-type of delayed fluorescence, which was observed at the same emission band of prompt (normal) fluorescence, and R-, E-, P-types of delayed fluorescences. For normal fluorescence, S1 state is decaying to S0 ground state. For E- and P-type of delayed fluorescences, T 1 state is decaying to S0 via S1 state, and for B-type of delayed fluorescence, T2 state is decaying to S 0 via S1 state. © 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az

Bayrakçeken, Fuat | Ari, F. | Telatar, Z.

Article | 2005 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy62 ( 04.05.2020 ) , pp.1151 - 1156

High resolution S0 › Sn and T1 › Tn electronic absorptions and B-type delayed fluorescence of 1,2,7,8-dibenzanthracene in polymethylmethacrylate (PMMA) were experimentally observed by flash and laser flash photolysis technique. Dibenzanthracene (hereafter DBA) molecules were excited in a two-step process. In the first step, an excited singlet is created, which undergoes intersystem crossing to triplet state, then T-T absorption creates an excited triplet dibenzanthracene molecule, which returns to the first excited singlet level by intersystem crossing. The re-created first excited singlet of dibenzanthracene decays back to the grou . . .nd state by emitting B-type of delayed fluorescence, which was observed at the same emission band of prompt (normal) fluorescence, and R-, E-, P-types of delayed fluorescences. For normal fluorescence, S1 state is decaying to S0 ground state. For E- and P-type of delayed fluorescences, T 1 state is decaying to S0 via S1 state, and for B-type of delayed fluorescence, T2 state is decaying to S 0 via S1 state. The spectrum image showing the absorption/emission bands mentioned was also examined by image processing techniques in order to improve the visual experience of each band by localizing to a specific region of interest (ROI). Experimental results illustrate how the exact location of emission/absorption bands was clearly extracted from the spectral image and further improvements in the visual detection of absorption/emission bands. © 2005 Elsevier B.V. All rights reserved Daha fazlası Daha az

Bayrakçeken, Fuat | Aktaş, S. | Toptan, M. | Ünlügedik, A.

Article | 2003 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy59 ( 1 ) , pp.135 - 138

High resolution absorption spectra of anisole and phenoxyl radical has been recorded in the vapor phase at room temperature by flash photolysis technique, and subsequent reactions have been investigated by kinetic spectroscopy. It was possible to follow the kinetics of the radical's decay which occurred predominantly by bimolecular recombination. The concentration of the phenoxyl radical calculated from the concentration of diphenoxyl molecules formed in the reaction cell during the optical pumping. The absolute extinction coefficient of this radical was measured from the absorption band at 291 nm, and found to be 0.95 × 10+4 mol-1 . . .l cm-l. © 2002 Elsevier Science B.V. All rights reserved Daha fazlası Daha az

Karaaslan, I.S. | Bayrakçeken, Fuat

Article | 2007 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy68 ( 5 ) , pp.1379 - 1381

The observation of triplet-triplet absorption of salicylidene-p-toluidine, is complicated by the possible colored isomer formation during the optical pumping. The short-lived (singlet-singlet) and long-lived (triplet-triplet) absorption spectra were recorded phographically by microsecond flash and nanosecond laser flash photolysis techniques. Salicylidene-aniline complexes were purified by repeated recrystallisation until further recrystallisation produced no further changes for X-ray diffraction pattern and optical absorption, emission properties. © 2007.

Bayrakçeken, Fuat

Article | 2008 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy69 ( 2 ) , pp.483 - 485

The reactions of photochemically generated deuterium atoms of selected initial translational energy with ethane have been investigated. At each initial energy the relative probability of the atoms undergoing reaction or energy loss on collision with ethane was investigated, and the phenomenological threshold energy was measured as 30 ± 5 kJ mol-1 for the abstraction from the secondary C-H bonds. The ratio of relative yields per bond, secondary:primary was ~3 at the higher energies studied. The correlation of threshold energies with bond dissociation energies, heats of reaction and activation energies is discussed for abstraction rea . . .ctions with several hydrocarbons. © 2007 Elsevier B.V. All rights reserved Daha fazlası Daha az

Bayrakçeken, Fuat | Sevinç, P.C.

Article | 2007 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy66 ( 1 ) , pp.184 - 187

Salicylideneaniline originally crystallized from a solution has lemon yellow color. Irradiation with near ultraviolet causes the color change from yellow to red. The red state changes spontaneously back to yellow in 2 ms. This change is accelerated by visible light. Kinetic data are reported in the temperature range between 10 and 60 °C, for the dark fading reactions of the colored isomers formed by the near ultraviolet irradiation. Observed the decay kinetics was first order reactions. Activation energies and entropies of activation are reported for ethanol. The observation of T-T absorption and emission were complicated due to the . . . colored isomer formation during the optical pumping. © 2006 Elsevier B.V. All rights reserved Daha fazlası Daha az

Bayrakçeken, Fuat | Karaaslan, I.S.

Article | 2003 | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy59 ( 12 ) , pp.2785 - 2789

High resolution electronic absorption spectra of aniline and anilino free radical have been recorded in the vapor phase at room temperature by flash photolysis technique, and subsequent reactions have been investigated by kinetic spectroscopy. It was possible to follow the kinetics of the anilino radical's decay which occurred predominantly by bimolecular recombination. Decay parameters of anilino free radical were measured from the absorption bands. © 2003 Elsevier Science B.V. All rights reserved.