Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Turkey (129)
- 1 (99)
- 2 (83)
- Classification (75)
- Deep learning (75)
-
- Machine learning (72)
- Optimization (69)
- Genetic algorithm (62)
- Synthesis (62)
- Adsorption (58)
- Geochemistry (55)
- Particle swarm optimization (53)
- Antimicrobial activity (47)
- 3 (45)
- Artificial neural network (42)
- Stability (40)
- Support vector machine (37)
- Phthalocyanine (36)
- Antibacterial activity (35)
- Feature extraction (33)
- Artificial neural networks (32)
- Feature selection (31)
- Wireless sensor networks (31)
- Molecular docking (30)
- Cytotoxicity (29)
- Copper (28)
- DFT (28)
- Oscillation (28)
- Power quality (28)
- COVID-19 (27)
- Publication Year
Articles 9361 - 9390 of 12093
Full-Text Articles in Entire DC Network
Deactivation Of A Co-Precipitated Co/Al_2o_3 Catalyst, Meltem Yildiz, Ayşe Ni̇lgün Akin
Deactivation Of A Co-Precipitated Co/Al_2o_3 Catalyst, Meltem Yildiz, Ayşe Ni̇lgün Akin
Turkish Journal of Chemistry
The effects of reaction temperature, feed ratio, space time, and CO percentage in feed on the deactivation conditions of a co-precipitated 36 wt% Co/Al_2O_3 catalyst in CO hydrogenation were investigated. Environmental-SEM-EDX and temperature-programmed reduction (TPR) studies were performed on used catalysts to investigate the effect of reaction conditions on catalyst deactivation. Intensive coke deposition on the catalyst was observed at a reaction temperature of about 573 K. Increasing the H_2/CO ratio also increased the catalyst activity. Methane formed as the main product at high H_2/CO ratios. Although catalyst activity did not change significantly during the 9-h reaction period at all …
Dielectric Behavior Of The Catalyst Zeolite Nay, Ertuğrul İzci̇, Ali̇me İzci̇
Dielectric Behavior Of The Catalyst Zeolite Nay, Ertuğrul İzci̇, Ali̇me İzci̇
Turkish Journal of Chemistry
Zeolites are crystalline hydrated aluminosilicates of alkaline and alkaline earth metals. The basic zeolite structure is an anionic frame of Si and Al T-atoms, which are tetrahedral and coordinated with oxygen atoms. The electrical properties of zeolites are of enormous technical importance due to their manifold applications as solid catalysts. Zeolite NaY was used in this investigation. Zeolite NaY is a synthetic zeolite and it has a faujasite structure. The electrical conductivity, dielectric permittivity, and loss factor of Na ion exchanged zeolite NaY was carried out in the 10^4-10^6 Hz frequency region at room temperature and different water contents using …
Catalytic Processes For Clean Hydrogen Production From Hydrocarbons, Zeynep İlsen Önsan
Catalytic Processes For Clean Hydrogen Production From Hydrocarbons, Zeynep İlsen Önsan
Turkish Journal of Chemistry
Conversion of hydrocarbon fuels to hydrogen with a high degree of purity acceptable for fuel cell operation presents interesting challenges for the design of new selective catalysts and catalytic processes. Natural gas, LPG, gasoline, and diesel are regarded as promising hydrocarbon fuels. Methanol has received attention despite its toxicity, and ethanol has recently become of interest as a much less toxic and renewable resource. Selective catalytic processes considered for commercial use are based on steam reforming and partial oxidation of these fuels. Autothermal reforming (ATR) or indirect partial oxidation (IPOX) combines total oxidation (TOX), steam reforming (SR), and water-gas shift …
Alcohols As Alternatives To Petroleum For Environmentally Clean Fuels And Petrochemicals, Ti̇mur Doğu, Di̇lek Varişli
Alcohols As Alternatives To Petroleum For Environmentally Clean Fuels And Petrochemicals, Ti̇mur Doğu, Di̇lek Varişli
Turkish Journal of Chemistry
In this review article, some of the challenging research areas related to the development of novel catalysts and catalytic processes for the chemical fixation of CO_2 by converting it to alcohols and ethers, and for the conversion of alcohols to olefins and other hydrocarbons are reviewed. Ethanol, methanol, and the ethers derived from them, such as DEE and DME, have good burning characteristics and may be considered attractive transportation fuel alternates. New processes for catalytic selective oxidation and dehydration of alcohols may open up new pathways for the production of olefins and other petrochemicals from non-petroleum feedstock. Developments in CO_2 …
Synthesis Of Piperazine Based Polyimide In The Presence Of Ionic Liquids, Bülent Alici, Süleyman Köytepe, Turgay Seçki̇n
Synthesis Of Piperazine Based Polyimide In The Presence Of Ionic Liquids, Bülent Alici, Süleyman Köytepe, Turgay Seçki̇n
Turkish Journal of Chemistry
Ionic liquids derived from imidazolium, pyridinium, and alkylammonium salts were investigated not only as catalysts but also as solvents in polymerization of 1,4-bis(3-aminopropyl) piperazine. Results were compared with the conventional polymerizations in N-methylpyrrolidone (NMP). The catalyst has not only a detectable influence on polymer solubility, but also the degrees of polymerization are notably higher. They are even greater than the values obtained by conventional 2-stage polymerization in organic liquids. Ionic liquids based on imidazolium salts seem preferable over pyridinium and alkylammonium salts due to the higher degree of polydispersity of the polyimides obtained. The glass transition temperatures and thermal stabilities …
Examination Of Some Commercial Sorptive Organobentonites, Müşerref Önal
Examination Of Some Commercial Sorptive Organobentonites, Müşerref Önal
Turkish Journal of Chemistry
For controlling organophilic partition nanophase (OPN) formation in some commercial sorptive organobentonites (OBs), 4 sample were selected randomly and examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), thermal gravimetric analysis (TGA), element analysis (EA), and nitrogen adsorption/desorption (N_2-AD) techniques. Since the d(001) values of the OB samples are between 1.94 and 3.36 nm, the pseudotrilayer or paraffin-type alkylammonium configuration located between the 2:1 layers of smectites is dominant. The bending and stretching type FTIR bands of the smectite surface and alkylammonium cations (AACs) are evidence of the formation of the OPN in the OBs. …
The Effect Of Ionic Electrolytes And Ph On The Zeta Potential Of Fine Coal Particles, Kemal Doymuş
The Effect Of Ionic Electrolytes And Ph On The Zeta Potential Of Fine Coal Particles, Kemal Doymuş
Turkish Journal of Chemistry
Many environmental problems are attributed to coal combustion and utilization, a subject receiving increasing attention worldwide. Some of these problems could be minimized or even avoided if coal cleaning, properly applied, was considered an economical and effective technique for removing hazardous elements or reducing their concentrations before combustion. The coal samples used in this study were separated into particle sizes of 4, 12, and 40 mesh. Then these samples were subjected to sink-float treatment in a ZnCl_2 solution of 1.3 density. The sample used for zeta potential determination was prepared by grinding both sink and float coal samples down to …
Synthesis Of New 5-Aryl Pyrido [3´, 2´: 4, 5] Thieno [2, 3-E] [1, 2, 3, 4] Tetrazolo [1, 5-C}] Pyrimidine Derivatives, Abolghasem Davoodnia, Mehdi Bakavoli, Mahsan Bashash, Mina Roshani, Rahele Zhiani
Synthesis Of New 5-Aryl Pyrido [3´, 2´: 4, 5] Thieno [2, 3-E] [1, 2, 3, 4] Tetrazolo [1, 5-C}] Pyrimidine Derivatives, Abolghasem Davoodnia, Mehdi Bakavoli, Mahsan Bashash, Mina Roshani, Rahele Zhiani
Turkish Journal of Chemistry
The synthesis of new 5-arylpyrido [3', 2': 4, 5] thieno [2, 3-e][1, 2, 3, 4] tetrazolo[1, 5-c] pyrimidine derivatives is described.
Catalytic Combustion Of Ethyl Acetate, Tuğba Gürmen Özçeli̇k, Süheyda Atalay, Erden Alpay
Catalytic Combustion Of Ethyl Acetate, Tuğba Gürmen Özçeli̇k, Süheyda Atalay, Erden Alpay
Turkish Journal of Chemistry
The catalytic combustion of ethyl acetate over prepared metal oxide catalysts was investigated. CeO, Co_2O_3, Mn_2O_3, Cr_2O_3, and CeO-Co_2O_3 catalysts were prepared on monolith supports and they were tested. Before conducting the catalyst experiments, we searched for the homogeneous gas phase combustion reaction of ethyl acetate. According to the homogeneous phase experimental results, 45% of ethyl acetate was converted at the maximum reactor temperature tested (350 °C). All the prepared catalysts were tested in order to find the best catalyst for the complete combustion of ethyl acetate. According to the results, all these catalysts produced higher conversion rates than that …
A Convenient And Efficient Synthesis Of N-Acylsulfonamides In The Presence Of Silica Phosphoric Acid Under Heterogeneous And Solvent-Free Conditions, Ahmad Reza Massah, Mina Dabagh, Maryam Afshar, Ahmad Reza Momeni, Hamid Aliyan, Hamid Javaherian Naghash
A Convenient And Efficient Synthesis Of N-Acylsulfonamides In The Presence Of Silica Phosphoric Acid Under Heterogeneous And Solvent-Free Conditions, Ahmad Reza Massah, Mina Dabagh, Maryam Afshar, Ahmad Reza Momeni, Hamid Aliyan, Hamid Javaherian Naghash
Turkish Journal of Chemistry
Reaction of sulfonamides with carboxylic acid anhydrides and chlorides in the presence of silica phosphoric acid provided N-acyl sulfonamides in good to high yields. All reactions were performed under mild conditions in solvent-free and heterogeneous systems and the products were obtained in high purity after a simple work-up. Silica phosphoric acid could be reused for 3 times without visible loss of activity.
Fused Heterocycles: Synthesis Of Some New Imidazopyridines As Anti-Mycobacterial Agents, Bi̇rgül Özden Kasimoğullari, Zafer Cesur
Fused Heterocycles: Synthesis Of Some New Imidazopyridines As Anti-Mycobacterial Agents, Bi̇rgül Özden Kasimoğullari, Zafer Cesur
Turkish Journal of Chemistry
The reaction of semicarbazones bearing an imidazo[1,2-a]pyridine ring system with mercaptoacetic acid was investigated. The anti-mycobacterial activity of the compounds thus obtained were evaluated against Mycobacterium tuberculosis H_{37}Rv, using rifampin as the standard. Only IVe showed activity at 6.25 \mu g mL^{-1}.
The Direct Electrochemical Synthesis Of Ti(Ii), Fe(Ii), Cd(Ii), Sn(Ii), And Pb(Ii) Complexes With N, N´-Bis(Salicylidene)-O-Phenylenediamine, Jianning Liu, Bing Zhang, Bowan Wu, Kejun Zhang, Shenli Hu
The Direct Electrochemical Synthesis Of Ti(Ii), Fe(Ii), Cd(Ii), Sn(Ii), And Pb(Ii) Complexes With N, N´-Bis(Salicylidene)-O-Phenylenediamine, Jianning Liu, Bing Zhang, Bowan Wu, Kejun Zhang, Shenli Hu
Turkish Journal of Chemistry
The electrochemical oxidation of anodic Ti, Fe, Cd, Sn, and Pb (=M) into acetonitrile solutions of N,N'-bis(salicylidene)-o-phenylenediamine [SalophH_2] gives the corresponding M(Saloph) complexes in high yield. The mechanism of the electrochemical reactions is discussed. SalophH_2 forms complexes (1:1 molar ratio) with titanium, iron, cadmium, tin, and lead ions. The complexes have been characterized by elemental analyses, molar conductivity measurements, and infrared and electronic spectral data. The SalophH_2 complexes of iron(II) and cadmium(II) have been further identified by ^1H-NMR and mass spectra.
Preconcentration Of Trace Elements On Amberlite Xad-4 Resin Functionalised With 1,2-Bis (O-Aminophenylthio) Ethane And Their Determination By Faas In Environmental Samples, Ömer Dalman, Volkan Numan Bulut, İsmai̇l Deği̇rmenci̇oğlu, Mehmet Tüfekçi̇
Preconcentration Of Trace Elements On Amberlite Xad-4 Resin Functionalised With 1,2-Bis (O-Aminophenylthio) Ethane And Their Determination By Faas In Environmental Samples, Ömer Dalman, Volkan Numan Bulut, İsmai̇l Deği̇rmenci̇oğlu, Mehmet Tüfekçi̇
Turkish Journal of Chemistry
The use of chemically modified XAD-4-1,2-bis (o-aminophenylthio) ethane chelating resin for preconcentrating Cr^{6+}, Mn^{2+}, Fe^{3+}, Co^{2+}, Cu^{2+}, Cd^{2+}, Zn^{2+}, Pb^{2+}, and Ni^{2+} was studied using flame atomic absorption spectrometry (FAAS) for metal monitoring in environmental samples. Cd^{2+}, Zn^{2+}, Pb^{2+}, and Ni^{2+} ions were quantitatively recovered at the rate of 96.0%, 101.0%, 101.0%, and 95.0%, respectively (RSD < 5%), from the studied solutions. The procedure is based on the retention of analytes on a short column of 1,2-bis (o-aminophenylthio) ethane-XAD-4 chelating resin from a buffered sample solution and subsequent elution with 1 M HNO_3. Various parameters, such as pH, eluent type, and concentration, flow rate of sample solution and matrix interference effect on the retention of the metal ions have been studied. The optimum pH for the sorption of the above-mentioned metal ions was about 6. The adsorption and batch capacity of adsorbent and loading half time (t_{1/2}) for Ni^{2+}, Zn^{2+}, Cd^{2+}, and Pb^{2+} were established. The limit of detection was 3.0 \mu g L^{-1} for Pb^{2+} and Ni^{2+}, 0.6 \mu g L^{-1} for Cd^{2+}, and 0.3 \mu g L^{-1} for Zn^{2+}. The validation of the procedure was carried out by analysis of certified reference materials and standard addition. The proposed enrichment method was applied to environmental samples from Trabzon.
Synthesis And Isolation Of 1-Cyclohex-1,2-Dien-1-Ylbenzene From 1-(2-Iodocyclohex-1-En-1-Yl)Benzene And 1-(2-Iodocyclohex-2-En-1-Yl)Benzene, Mustafa Ceylan, Yakup Budak, M. Burcu Gürdere, İrfan Özdemi̇r, Esra Findik
Synthesis And Isolation Of 1-Cyclohex-1,2-Dien-1-Ylbenzene From 1-(2-Iodocyclohex-1-En-1-Yl)Benzene And 1-(2-Iodocyclohex-2-En-1-Yl)Benzene, Mustafa Ceylan, Yakup Budak, M. Burcu Gürdere, İrfan Özdemi̇r, Esra Findik
Turkish Journal of Chemistry
The key compounds, 1-(2-iodocyclohex-1-en-1-yl) benzene (12) and 1-(2-iodocyclohex-2-en-1-yl) benzene (13), for the generation of 1-cyclohex-1,2-dien-1-ylbezene (20) were synthesized starting with cyclohexanone. Separate reactions of 12 and 13 with KOtBu in benzene in a sealed tube at 180 °C gave 6 products: 1-cyclohex-1-en-1-ylbenzene (8), 2-phenylcyclohexanone (10), 1,8-diphenyl-2,3,4,4a,4b,5,6,7-octahydrobiphenylene (21), 8a-phenyl-1,2,3,4,6,7,8,8a-octahyd-rotriphenylene (22), 1,2-diphenylcyclohexene (23), and 1-(2-tert-butoxycyclohex-1-enyl) benzene (24). In addition, reactions of 12 and 13 under the same conditions in the presence of diphenylisobenzofuran and furan as trapping reagents afforded the [4 + 2] cyclo-adducts 30, 31, and 32 in good yields, respectively.
Synthesis And Characterization Of Nife_2o_4 Nano-Octahedrons By Edta-Assisted Hydrothermal Method, Nermi̇n Kasapoğlu, Abdulhadi̇ Baykal, Muhammet S. Toprak, Yüksel Köseoğlu, Harun Bayrakdar
Synthesis And Characterization Of Nife_2o_4 Nano-Octahedrons By Edta-Assisted Hydrothermal Method, Nermi̇n Kasapoğlu, Abdulhadi̇ Baykal, Muhammet S. Toprak, Yüksel Köseoğlu, Harun Bayrakdar
Turkish Journal of Chemistry
Octahedral-like NiFe_2O_4 ferrite nanocrystals were synthesized using EDTA-assisted hydrothermal method under mild conditions. XRD and FTIR analysis were used for composition and structure investigation. XRD analysis revealed a pure ferrite phase with high crystallinity. Morphological investigation by SEM showed octahedral nanocrystals with an average particle size of \sim 40 nm. Crystallite size calculated from XRD peak broadening resulted in an average crystallite size of 39 nm, matching well with the SEM observations. TEM analysis and corresponding electron diffraction confirmed the octahedral morphology and single crystallinity of octahedral nanoparticles. Magnetic measurements showed that NiFe_2O_4 octahedrons have smaller coercivity than bulk ferrite …
Dinuclear Molybdenum Tetracarbonyl Complexes Of Tetradentate Nitrogen Ligands And Intermolecular Hydrogen Bonding In The Crystal Structure Of N,N´-Bis-[1-(Pyridin-2-Yl)Ethylidene]-Ethane-1,2-Diamine, Ayfer Menteş, Seda Sezek, M. Emre Hanhan, Orhan Büyükgüngör
Dinuclear Molybdenum Tetracarbonyl Complexes Of Tetradentate Nitrogen Ligands And Intermolecular Hydrogen Bonding In The Crystal Structure Of N,N´-Bis-[1-(Pyridin-2-Yl)Ethylidene]-Ethane-1,2-Diamine, Ayfer Menteş, Seda Sezek, M. Emre Hanhan, Orhan Büyükgüngör
Turkish Journal of Chemistry
Multidentate N-ligands (Schiff bases) were prepared by the condensation of 2-acetylpyridine or 2-benzoylpyridine, and 1,2-diaminoethane or 1,6-diaminohexane (2:1 ratio) in ethanol. These ligands were reacted with Mo(CO)_6 to obtain dinuclear metal tetracarbonyl compounds. Both terminal amine groups were seen to form imines from the reaction of mono-ketones with diamines in 2:1 or 1:1 ratios. The structures of these ligands and metal complexes were characterized by elemental analysis, and FT-IR, ^1H-NMR, ^{13}C-NMR, and LC-MS spectral techniques. N,N'-bis[1-(pyridin-2-yl)ethylidene]ethane-1, 2-diamine, which was obtained by the reaction of 2-acetylpyridine and 1,2-diaminoethane, was also characterized by single crystal X-ray structure analysis. The crystal packing is …
Synthesis Of The Amide Derivatives Of 3-[1-(3-Pyridazinyl)-5-Phenyl-1h-Pyrazole-3-Yl]Propanoic Acids As Potential Analgesic Compounds, Erden Banoğlu, Murat Şüküroğlu, Burcu Çalişkan Ergün, Sultan Nacak Baytaş, Eda Aypar, Mustafa Ark
Synthesis Of The Amide Derivatives Of 3-[1-(3-Pyridazinyl)-5-Phenyl-1h-Pyrazole-3-Yl]Propanoic Acids As Potential Analgesic Compounds, Erden Banoğlu, Murat Şüküroğlu, Burcu Çalişkan Ergün, Sultan Nacak Baytaş, Eda Aypar, Mustafa Ark
Turkish Journal of Chemistry
A series of structurally diverse amide derivatives of 3-[1-(3-pyridazinyl)-5-phenyl-1H-pyrazole-3-yl]propanoic acids were prepared and tested for their in vivo analgesic activity using an acetic acid induced writhing test. All the test compounds displayed approximately equipotent analgesic activity to aspirin. The results showed that the analgesic activity of 5a, 5f, 5n, and 5o is significantly higher than that of 5d.
Environmental Impact And Drainage Geochemistry In The Vicinity Of The Harput Pb-Zn-Cu Veins, Elazığ, Se Turkey, Leyla Kalender, Cemal Bölücek
Environmental Impact And Drainage Geochemistry In The Vicinity Of The Harput Pb-Zn-Cu Veins, Elazığ, Se Turkey, Leyla Kalender, Cemal Bölücek
Turkish Journal of Earth Sciences
The aim of this study was to examine the environmental impact of major, minor and rare-earth elements (REE) in spring waters and major and minor elements in stream sediments proximal to known vein-type Pb-Zn-Cu ores. Accordingly, a total of 21 water samples were collected from natural springs in the Köprücük, Çolaklı, Kabakçılar and Ekinli areas where ore-bearing rocks are widely exposed. Stream-sediment samples were taken from the Kurt, Kızıldağ and Karacalar and Billurik streams, and a total of 57 samples were sieved to three different size fractions (-80 +140, -140 +200 and -200 mesh) and analyzed by ICP-MS and IE …
The Dikili-Çandarlı Volcanics, Western Turkey: Magmatic Interactions As Recorded By Petrographic And Geochemical Features, Zeki̇ye Karacik, Yücel Yilmaz, Julian A. Pearce
The Dikili-Çandarlı Volcanics, Western Turkey: Magmatic Interactions As Recorded By Petrographic And Geochemical Features, Zeki̇ye Karacik, Yücel Yilmaz, Julian A. Pearce
Turkish Journal of Earth Sciences
Located in the northwestern part of the Aegean region, Dikili-Çandarlı volcanic suite contains products representative for the western Anatolian Miocene volcanism. They can be divided into two main groups: the Dikili and the Çandarlı groups. The Dikili group is Early-Middle Miocene in age and consists mainly of pyroclastic rocks, andesitic-dacitic lavas, lava breccia, lahar flows and associated sedimentary rocks. The lavas contain disequilibrium phenocrysts assemblages. The Çandarlı group consists of Upper Miocene-Pliocene lava and sediment associations. The volcanic rocks consist mainly of rhyolitic domes and basaltic trachyandesite-basaltic andesite lavas erupted along the NW-SE- and NE-SW-trending fault systems; the faults controlled …
Jurassic Volcanism In The Eastern Pontides: Is It Rift Related Or Subduction Related?, Cüneyt Şen
Jurassic Volcanism In The Eastern Pontides: Is It Rift Related Or Subduction Related?, Cüneyt Şen
Turkish Journal of Earth Sciences
The Jurassic volcanic rocks in the centre of the northern zone (south of Trabzon City) provide important constraints on the evolution of Pontides. The investigated volcanic rocks form a transitional series between tholeiitic and calc-alkaline, and is dominated by basalt, basaltic andesite and andesite. Geochemically, they are enriched in LILE and LREE contents and depleted in HFSE [(La/Yb)_N= 2.2 - 8.5; (Nb/La)_N= 0.1 - 0.77)] compared to mid-ocean ridge basalts and have radiogenic Nd isotope ratios of \epsilonNd(210 Ma)= -0.72 to 3.24. These trace element and isotope data suggest that these rocks were derived from low degrees of partial melting …
Exact Analytical Solution Of The Diode Ideality Factor Of A Pn Junction Device Using Lambert W-Function Model, Habi̇be Bayhan, A. Sertap Kavasoglu
Exact Analytical Solution Of The Diode Ideality Factor Of A Pn Junction Device Using Lambert W-Function Model, Habi̇be Bayhan, A. Sertap Kavasoglu
Turkish Journal of Physics
The paper presents a new analytical method for extracting the diode ideality factor of a p-n junction device using Lambert W-function model and the dark current-voltage data. The extracted values are found to be in good agreement with those calculated experimentally from dark current-voltage characteristics.
Structural, Electrical And Infrared Studies Of Ni_{0.7}Cd_{0.3}Sm_Xfe_{2-X}O_4 Ferrite, M. Z. Said, D. M. Hemeda, S. Abdel Kader, G. Z. Farag
Structural, Electrical And Infrared Studies Of Ni_{0.7}Cd_{0.3}Sm_Xfe_{2-X}O_4 Ferrite, M. Z. Said, D. M. Hemeda, S. Abdel Kader, G. Z. Farag
Turkish Journal of Physics
A series of samples of the system Ni_{0.7}Cd_{0.3}Sm_xFe_{2-x}O_4 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06) were prepared by the usual ceramic technique. X-ray diffraction, infrared spectroscopy (IR) and electrical properties were studied. The X-ray diffraction pattern confirms the presence of spinel phase structure for the sample without Sm content. For the samples with Sm ions, some diffraction peaks appeared which belongs to the orthorhombic phase structure. The main two absorption bands in IR spectra were observed around 600 cm^{-1} (\upsilon_1), which was attributed to stretching vibration of tetrahedral groups Fe^{3+}-O^{2-}, and that around 400~cm^{-1} (\upsilon _2) was …
Variational Ground State Approach For A Tunnelling Exciton Coupled To Phonons, Dezider Kulak
Variational Ground State Approach For A Tunnelling Exciton Coupled To Phonons, Dezider Kulak
Turkish Journal of Physics
In this paper a variational study of a tunnelling exciton (Frenkel exciton) coupled to an arbitrary number of phonon modes is presented. The results of our model are presented both for weak non-adiabatic cases and for strong cases; and we come to the conclusion that the tunnelling reduction factor, the ground state energy of the tunnelling exciton-phonons system, and the mean number of ground state phonons, as the functions of the exciton-phonons coupling strength, are continuous, a condition that does not apply in cases of the tunnelling exciton-phonons models presented in the previous studies. In comparison with the previous studies, …