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Article Citation - WoS: 58Two-Dimensional Fluorinated Boron Sheets: Mechanical, Electronic, and Thermal Properties(Amer Chemical Soc, 2018) Pekoz, Rengin; Konuk, Mine; Kilic, M. Emin; Durgun, EnginThe synthesis of atomically thin boron sheets on a silver substrate opened a new area in the field of two-dimensional systems. Similar to hydrogenated and halogenated graphene, the uniform coating of borophene with fluorine atoms can lead to new derivatives of borophene with novel properties. In this respect, we explore the possible structures of fluorinated borophene for varying levels of coverage (BnF) by using first-principles methods. Following the structural optimizations, phonon spectrum analysis and ab initio molecular dynamics simulations are performed to reveal the stability of the obtained structures. Our results indicate that while fully fluorinated borophene (BF) cannot be obtained, stable configurations with lower coverage levels (B4F and B2F) can be attained. Unveiling the stable structures, we explore the mechanical, electronic, and thermal properties of (BnF). Fluorination significantly alters the mechanical properties of the system, and remarkable results, including direction-dependent variation of Young's modulus and a switch from a negative to positive Poisson's ratio, are obtained. However, the metallic character is preserved for low coverage levels, and metal to semiconductor transition is obtained for B2F. The heat capacity at a low temperature increases with an increasing F atom amount but converges to the same limiting value at high temperatures. The enhanced stability and unique properties of fluorinated borophene make it a promising material for various high-technology applications in reduced dimensions.Book Part Media and Democracy in Turkey an Analysis on the News Media Framing of Gezi Park Protests(Routledge, 2016) Sayin, Cagkan; Toros, Emre[No Abstract Available]Article Citation - WoS: 4Citation - Scopus: 4Optical Characterization of (tlins2)0.5< Crystal by Ellipsometry: Linear and Optical Constants for Optoelectronic Devices(Springer, 2023) Guler, I.; Isik, M.; Gasanly, N.TlInSSe [(TlInS2)(0.5)(TlInSe2)(0.5)] crystals have garnered significant attention as promising candidates for optoelectronic applications due to their exceptional optoelectrical characteristics. This study focused on investigating the linear and nonlinear optical properties of TlInSSe layered single crystals through ellipsometry measurements. The X-ray diffraction analysis revealed the presence of four distinct peaks corresponding to a monoclinic crystalline structure. In-depth analysis was conducted to examine the variations of refractive index, extinction coefficient, and complex dielectric function within the energy range of 1.25-6.15 eV. By employing derivative analysis of the absorption coefficient and utilizing the Tauc relation, the indirect and direct bandgap energies of TlInSSe crystals were determined to be 2.09 and 2.26 eV, respectively. Furthermore, this research paper presents findings on oscillator energy, dispersion energy, Urbach energy, zero and high frequency dielectric constants, plasma frequency, carrier density to effective mass ratio, nonlinear refractive index, and first-order and third-order nonlinear susceptibilities of TlInSSe crystals.Conference Object The Effect of Hemodialysis Environment and Reuse Solution on the Stability of High Flux Polyamide Membranes(Dustri-verlag Dr Karl Feistle, 2010) Neslihan, S.; Emin, A. M.; Cuma, B.; Metin, U.; Hikmet, U. A.[No Abstract Available]Article Citation - WoS: 17Citation - Scopus: 16The Approximation by q-bernstein Polynomials in the Case q ↓ 1(Springer Basel Ag, 2006) Ostrovska, SLet B-n (f, q; x), n = 1, 2, ... , 0 < q < infinity, be the q-Bernstein polynomials of a function f, B-n (f, 1; x) being the classical Bernstein polynomials. It is proved that, in general, {B-n (f, q(n); x)} with q(n) down arrow 1 is not an approximating sequence for f is an element of C[0, 1], in contrast to the standard case q(n) up arrow 1. At the same time, there exists a sequence 0 < delta(n) down arrow 0 such that the condition 1 <= q(n) <= delta(n) implies the approximation of f by {B-n(f, qn; x)} for all f is an element of C[0, 1].Conference Object Citation - WoS: 15Citation - Scopus: 15Refractive Index, Static Dielectric Constant, Energy Band Gap and Oscillator Parameters of Ga2ses Single Crystals(Wiley-v C H verlag Gmbh, 2007) Qasrawi, A. F.; Gasanly, N. M.The optical properties of Bridgman method grown Ga2SeS crystals have been investigated by means of room-temperature transmittance and reflectance spectral analysis. The optical data have revealed direct and indirect allowed transition band gaps of 2.49 and 2.10 eV, respectively. The room-temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as 20.93 eV and 4.01 eV, 6.21 and 2.49, respectively.Article Citation - WoS: 8Citation - Scopus: 8Spectroscopic ellipsometry study of Bi12TiO20 single crystals(Springer, 2021) Isik, M.; Gasanly, N. M.; Darvishov, N. H.; Bagiev, V. E.Bi12XO20 (X: Si, Ge, Ti, etc.) ternary compounds have attracted attention especially due to their fascinating photorefractive characteristics. The present paper introduces the structural and optical characteristics of Bi12TiO20 single crystals grown by Czochralski method. X-ray diffraction pattern of the compound exhibited sharp and intensive peaks corresponding to parallel planes of cubic crystalline structure. The lattice constant of the cubic structure was determined as a = 1.0118 nm using a diffraction pattern indexing program. The optical characterization of the Bi12TiO20 single crystals was carried through spectroscopic ellipsometry experiments performed in the 1.2-5.0 eV spectral range. The spectral dependencies of refractive index, extinction coefficient, and complex dielectric function were revealed analyzing experimental ellipsometric data under the light of sample-air optical model. The band gap energy of the compound was determined as 3.34 eV from the analyses of absorption coefficient. Three critical points at 3.51, 4.10, and 4.71 eV were obtained from the analyses of components of dielectric function using their second-energy derivative spectra.Book Part Citation - WoS: 1Theorizing Europeanization Through Enlargement Pull-And Model(Routledge, 2017) Yilmaz, Gozde[No Abstract Available]Article Citation - WoS: 19Citation - Scopus: 18Deviations From Born-Oppenheimer Theory in Structural Chemistry: Jahn-Teller, Pseudo Jahn-Teller, and Hidden Pseudo Jahn-Teller Effects in C3h3< and C3h3<(Amer Chemical Soc, 2013) Kayi, H.; Garcia-Fernandez, P.; Bersuker, I. B.; Boggs, J. E.The electronic structure and vibronic coupling in two similar molecular systems, radical C3H3 and anion C3H3-, in ground and excited states, are investigated in detail to show how their equilibrium structures, in deviation from the Born-Oppenheimer approximation, originate from the vibronic mixing of at least two electronic states, producing the Jahn-Teller UT), pseudo JT (PJT), and hidden PJT effects. Starting with the high-symmetry geometry D3h of C3H3, we evaluated its 2-fold degenerate ground electronic state 2E" and two lowest excited states 2A,' and 2E' and found that all of them contribute to the distortion of the ground state via the JT vibronic coupling problem E" e' and two PJT problems (E" + A(1)') circle star e" and (E" + E') circle times (a2" + e"); all the three active normal modes e'(1335 e"(1030 cm(-1)), and a2"(778 cm(-1)) are imaginary, meaning that all the three vibronic couplings are sufficiently strong to cause instability, albeit in different directions. The first of them, the ground state JT effect, enhances one of the C-C bonds (toward an ethylenic form with C-2v symmetry), while the two PJT effects produce, respectively, cis (a(2)" toward C-3v symmetry) and trans (e") puckering of the hydrogen atoms. As a result, C3H3 has two coexisting equilibrium configurations with different geometry. In the C3H3- anion, the ground electronic state in DA symmetry is an orbitally nondegenerate spin triplet (3)A(2)' with a group of close in energy singlet and triplet excited states in the order of (1)A(1),', (3)A(1)', E-1", E-3", and E-1'. This shows that two PJT couplings, (3A(2)' + (3)A(1)") circle times a(2)" and (3A2' + 3E") e", may influence the geometry of the equilibrium structure in the 3A2' state. Indeed, both vibrational modes, a(2)"(1034 cm(-1)) and e"(1284 cm(-1)), are imaginary in this state. Similar to the radical case, they produce, respectively, cis (a(2)") and trans (e") puckering of the hydrogen atoms, but no e' distortion of the basic C-3 triangle; the equilibrium configuration with Cs symmetry occurs along the stronger e" distortions. Another higher-in-energy triplet-state minimum with C-2v symmetry emerges as a result of a strong JTE in the excited 3E" electronic state. In addition to these APES minima with spin-triplet electronic states, the system has a coexisting minimum with a spin-singlet electronic state, which is shown to be due to the hidden PJT effect that couples two singlet excited states. The two lowest equilibrium configurations of the C3H3- anion with different geometry and spin realize a (common to all electronic e(2) configurations) magnetic and structural bistability accompanied by a spin crossover. Some general spectroscopic consequences are also noted. As a whole, this article is intended to demonstrate the efficiency of the vibronic coupling approach in rationalizing the origin of complicated structural features of molecular systems as due to a combination of nonadiabatic JT effects.Article Citation - Scopus: 1Investigations of Λ States With Spin-Parity 3 ± 2(Amer Physical Soc, 2024) Azizi, K.; Sarac, Y.; Sundu, H.The present study provides spectroscopic investigations of spin-32 A baryons with both positive and negative parities. The analysis mainly focuses on three states, namely 1P, 2P, and 2S, and corresponding masses are calculated using the QCD sum rule method. To implement the method, we apply two types of interpolating currents with octet and singlet quantum numbers and compare the corresponding results with the reported masses of experimentally observed states. From the comparisons, it is extracted that the results of interpolating current with octet quantum numbers are in good agreement with the experimentally measured masses. The masses obtained with this interpolating current are m = 1513.64 +/- 8.76 MeV for 1P state with JP = 3 -, m' = 1687.91 +/- 0.31 MeV for 2P state with JP = 3 - and m = 1882.37 +/- 11.95 MeV for 2S state with JP = 3 + and they are consistent with the experimental masses of A(1520), A(1690), and A(1890), respectively, which confirm their spin-parity quantum numbers. Besides, we calculate the corresponding current coupling constants, which are utilized as inputs in the calculations of different form factors defining the widths of the states under study.
