Artykuły w czasopismach: „Transfer of oscillator strength”

1

Brunhes, T., R. André, A. Arnoult, J. Cibert i A. Wasiela. "Oscillator strength transfer fromXtoX+in a CdTe quantum-well microcavity". Physical Review B 60, nr 16 (15.10.1999): 11568–71. http://dx.doi.org/10.1103/physrevb.60.11568.

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Padma, R., i PC Deshmukh. "Optical Oscillator Strengths from 'Electron-impact Photoionisation' in the RCX Potential". Australian Journal of Physics 46, nr 4 (1993): 497. http://dx.doi.org/10.1071/ph930497.

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Electron-impact collisions excite optically allowed as well as optically forbidden transitions. In this paper we report details of optical oscillator strengths calculated using the RCS potential. The oscillator strengths have been calculated using the small-momentum-transfer limit (K -+ 0) of the electron-impact generalised oscillator strength. Results for the Cooperminimum trajectories for some high-Z (82-90) atoms and for Kr 3p ionisation are reported. These have been found to be in fair agreement with results of previous calculations in which more involved techniques were used. The present results offer further support to the utility of the RCS potential in atomic physics by providing first estimates of some important atomic properties, using a relativistic atomic potential which is computationally not very demanding

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Farges, J. P., A. Brau i P. Dupuis. "Infrared Oscillator Strength Study of Charge Transfer in Two TCNQ Salts". Molecular Crystals and Liquid Crystals Incorporating Nonlinear Optics 186, nr 1 (sierpień 1990): 137–41. http://dx.doi.org/10.1080/00268949008037203.

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KANO, HIDEAKI, TAKASHI SAITO, AKIKATSU UEKI i TAKAYOSHI KOBAYASHI. "FIRST OBSERVATION OF DYNAMIC INTENSITY BORROWING INDUCED BY COHERENT MOLECULAR VIBRATIONS IN J-AGGREGATES REVEALED BY SUB-5-FS SPECTROSCOPY". International Journal of Modern Physics B 15, nr 28n30 (10.12.2001): 3817–20. http://dx.doi.org/10.1142/s0217979201008743.

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Sub-5-fs spectroscopy of porphyrin J-aggregates reveals for the first time coherent molecular vibration coupled to the Frenkel exciton. The oscillations with the frequency of 244cm-1 are described by a plus-cosine function for bleaching and a minus-cosine function for induced absorption. The coherent oscillation is explained by a modulated transition dipole moment, which is due to the transfer of an oscillator strength from the intense B-band to the weak Q-band through the ruffling mode with 244cm-1-frequency.

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Bonham, R. A., M. Inokuti i R. S. Barbieri. "On the slope of the generalized oscillator strength in the limit of zero momentum transfer". Journal of Physics B: Atomic, Molecular and Optical Physics 26, nr 19 (14.10.1993): 3363–78. http://dx.doi.org/10.1088/0953-4075/26/19/024.

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Saenz, Alejandro, i Wolf Weyrich. "The Generalised Oscillator-Strength Density of the Helium Atom, Calculated by a New Implementation of the Complex-Coordinate Method". Zeitschrift für Naturforschung A 48, nr 1-2 (1.02.1993): 243–50. http://dx.doi.org/10.1515/zna-1993-1-245.

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Abstract We report a calculation of the generalised oscillator-strength density (GOSD) of the helium atom for low momentum transfer. The calculation was performed by extraction of the searched entity from the resolvent of the complex-rotated Hamiltonian. That Hamiltonian was found using a standard ab-initio program without any change in the program code. The shape of the Bethe surface is reproduced (including resonances and the absorption edge). However, with increasing momentum transfer the magnitude of the calculated values for the Bethe ridge becomes too small. This is clearly demonstrated by an evaluation of the Bethe sum as a function of the momentum transfer. A comparison with recent additional theoretical data shows that the deviations are due to the employed basis set.

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Wu, Yuting, Yanan Zhu, Zewei Zhang, Chongguang Zhao, Junpeng He, Chaoyi Yan i Hong Meng. "Narrowband Deep-Blue Multi-Resonance Induced Thermally Activated Delayed Fluorescence: Insights from the Theoretical Molecular Design". Molecules 27, nr 2 (6.01.2022): 348. http://dx.doi.org/10.3390/molecules27020348.

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Multi-resonance thermal activated delayed fluorescence (MR-TADF) has been promising with large oscillator strength and narrow full width at half maxima of luminescence, overcoming the compromise of emission intensity and energy criteria of traditional charge transfer TADF frameworks. However, there are still limited theoretical investigations on the excitation mechanism and systematic molecular manipulation of MR-TADF structures. We systematically study the highly localized excitation (LE) characteristics based on typical blue boron-nitrogen (BN) MR-TADF emitters and prove the potential triangular core with theoretical approaches. A design strategy by extending the planar π-conjugate core structure is proposed to enhance the multiple resonance effects. Moreover, several substituted groups are introduced to the designed core, achieving color-tunable functions with relatively small energy split and strong oscillator strength simultaneously. This work provides a theoretical direction for molecular design strategy and a series of potential candidates for highly efficient BN MR-TADF emitters.

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Dolomatov, Mikhail Yu, Kamil F. Latypov i Ella A. Kovaleva. "Prediction of vertical ionization potentials for organic compounds by integral characteristics of optical spectra and the number of protons in molecules". Butlerov Communications 58, nr 6 (30.06.2019): 62–72. http://dx.doi.org/10.37952/roi-jbc-01/19-58-6-62.

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In this review, the authors summarize the results of the first vertical ionization potentials with the structural and spectral integral descriptors of organic compounds: the integral oscillator strength defined in the visible or UV regions of the spectrum and the total number of protons in organic molecules. The adequate non-linear regression models relating the potentials of ionization as functions of the integral oscillator strength in the range between 6.53 eV and 1.63 eV (from 190 to 760 nm) and the total number of protons in organic molecules. The regularities were allowing to estimate the first ionization potentials for organic oxygen – and nitrogen-containing compounds established. The established regularities are interpreted as the influence of exchange and electrostatic interactions on the energies of the highest occupied molecular orbitals. The ionization potentials were calibrated according to the method of Hartree-Fock (RHF) method using 6-31G(d,p) basis set from the Koopmans' theorem. The obtained models allow us to estimate first ionization potentials of organic oxygen-and nitrogen-containing molecular systems by the integral oscillator strength and by the number of protons with an accuracy of 0.4 to 9%. This accuracy is quite suitable for practical applications. The research results can be used in chemistry, photochemistry, molecular electronics, photonics, and physical chemistry to study electron transfer processes, the characteristics of the band structure of nanoparticles. The present paper examples confirmed by statistical data processing.

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MAN, ZHONG-XIAO, SU FANG i YUN-JIE XIA. "ENTANGLEMENT DYNAMICS MODULATED BY COUPLING STRENGTH IN CAVITY QED". International Journal of Quantum Information 06, nr 02 (kwiecień 2008): 341–46. http://dx.doi.org/10.1142/s0219749908003414.

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We study the dynamics of entanglement for a four-qubit system in cavity QED. Two initially entangled atoms A and B are coupled respectively with spatially separate cavities a and b with coupling strengths gA and gB. We show that when gA ≠ gB, the entanglement will oscillate in the period of entanglement sudden death (ESD) for gA = gB, and the oscillation times are related to the ratios between gA and gB. Also, we show that the coupling strengths have the same effects on the entanglement evolution and energy transfer.

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OKAMOTO, SHINJI, SHOSAKU TANAKA i HAJIME YAMAMOTO. "ENERGY-TRANSFER PROCESS IN RARE-EARTH-ION DOPED SrTiO3". International Journal of Modern Physics B 15, nr 28n30 (10.12.2001): 3924–27. http://dx.doi.org/10.1142/s0217979201009013.

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Enhancement of emission intensity of rare-earth-ion doped SrTiO 3 by Al addition has been investigated. In the case of Pr 3+ and Tb 3+, addition of 23-mol% Al intensifies emission by more than 200 times. In contrast, the addition of 20 mol% Al intensifies emission at most by three times in the case of other rare-earth ions. The temperature dependence of PL spectra shows that the energy transfer from carriers to Pr 3+ or Tb 3+ ions is much more efficient than that to other rare-earth ions in SrTiO 3. It can be speculated that the energy transfer in SrTiO 3: Pr 3 or Tb 3+ occurs from carriers to Pr 3+ or Tb 3+ ion via 4f-5d transitions, which are much higher in oscillator strength than 4f-4f transitions.

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Karim, A. M. M. Tanveer, M. K. R. Khan, M. N. H. Liton, M. Kamruzzaman, M. S. Hossain i Shengmei Chen. "Nonlinear optical response, theoretical efficiencies, and high photosensitivity of CH₃NH₃PbI_3−xCl_x thin films for photonic applications". AIP Advances 12, nr 6 (1.06.2022): 065126. http://dx.doi.org/10.1063/5.0086386.

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In this paper, we have investigated the nonlinear optical response and theoretical efficiency of CH3NH3PbI3−xClx thin films from the optical transmission and reflection measurements. The dispersion of the complex refractive index is evaluated using the Wemple–DiDomenico single oscillator model. The oscillator energy (E0) of CH3NH3PbI3−xClx follows by an empirical relationship with optical bandgap (Eg) as E0 ≈ 2.41 Eg for chemical dip coating, spray, and E0 ≈ 1.63 Eg for dipping deposited samples, respectively. The long wavelength refractive index, average oscillator wavelength, and oscillator strength are also determined using the Sellmeier oscillator equation. The estimated third-order nonlinear optical susceptibility is found to be the order of 10−12 esu. The incident photon and charge carrier interaction in CH3NH3PbI3−xClx is studied from the dielectric response of the samples. The charge carrier excitation is found higher at lower wavelength and experienced bulk excitation in volume while surface excitation on the surface region. The optical conductivity of CH3NH3PbI3−xClx is notably high, which leads to an increase in carrier transfer through the extrinsic halide perovskite material expedient for higher conversion efficiency. The highest theoretical efficiency of CH3NH3PbI3−xClx is estimated to be 17.4%, which is in excellent agreement with the experimental report. From photosensitivity study, it is confirmed that CH3NH3PbI3−xClx films are highly photosensitive. All these results comprehend that CH3NH3PbI3−xClx is a potential candidate for photonic applications.

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LIMA, Francisco José Santos; e., Jean Lucas Carvalho da SILVA i Ademir Oliveira da SILVA. "MOLECULAR MODELING AND EVALUATION OF THERMAL, CONDUTIMETRIC AND SPECTRUM PROPERTIES OF ACID MALEIC FOR APPLICATION IN PROMISSORY CHEMICAL SYSTEMS". Periódico Tchê Química 16, nr 31 (20.01.2019): 937–43. http://dx.doi.org/10.52571/ptq.v16.n31.2019.937_periodico31_pgs_937_943.pdf.

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In this work the chemical properties of the maleic acid C4H4O4 were investigated, through the modeling and molecular reactivity parameters, pH measurements and acid-base equilibrium study using the RAZES 1.0 program, molar conductivity measurements, thermal analysis, uv-visible spectra and oscillator strength to evaluate their potential viability in forming promising complex chemical systems capable of transforming, via inter-system transfer, dispersed electromagnetic radiation into selective light emitting systems or converters of radiation into electricity. It has been observed that the counter-cation of this acid has compatible molecular reactivity parameters for the formation of stable chemical bonds with metal receptors of electrons. Its 2: 1 electrolytic behavior reveals that it can function as a versatile, mono- and / or bidentate chelator, as well as mono- and / or bivalent chelator in the formation of complex adducts. Its thermal stability extends to 100ºC, where it decomposes almost totally to 400ºC under atmosphere of N2, ending with some carbon residue. Their spectra show strong absorption in the ultraviolet region, with the oscillator strength of the order of organic dyes, a property that reflects a careful investigation in the area of research and possible application in promising complex chemical systems.

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Basri, G., i G. W. Marcy. "Limits on the Magnetic Flux of a Pre-Main Sequence Star". International Astronomical Union Colloquium 130 (1991): 401–6. http://dx.doi.org/10.1017/s0252921100080003.

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AbstractWe attempt to detect a magnetic field on the weak T Tauri star, TAP35, via the enhanced equivalent widths of Zeeman-broadened absorption lines. We synthesize 25 Fe I lines, having a range of Zeeman sensitivities, using an LTE Stokes line-transfer calculation. The oscillator strengths of all lines are empirically determined a priori using the same line-transfer code applied to the spectrum of the magnetically quiet star, τ Ceti. The Fe abundance of TAP35 was established by synthesizing lines that are insensitive to Zeeman splitting. We find that the equivalent widths, Weq, of Zeeman-sensitive lines in TAP35 are systematically enhanced relative to the Zeeman-insensitive lines, consistent with the presence of widespread, kilogauss fields. The excess Weq can be explained by a product of field strength and surface filling factor (Bf) of 1 kiloGauss. A strong upper limit can be placed on the product of those two quantities, Bf < 2 kG. This measurement bears on the physics of T Tauri coronae, chromospheres, dynamos, and accretion-disk boundary layers.

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Dai, Dejian, Chengyu Zhang, Nguyen Thi Dieu Thuy, Guo Zhao, Wei Lu i Jiyang Fan. "Strong fluorescence quenching of carbon dots by mercury(II) ions: Ground-state electron transfer and diminished oscillator strength". Diamond and Related Materials 126 (czerwiec 2022): 109076. http://dx.doi.org/10.1016/j.diamond.2022.109076.

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Hayakawa, Tomokatsu, i Masayuki Nogami. "High-Efficient Eu³⁺ Red Emission due to Excitation Energy Transfer from Nano-Sized SnO₂ Crystals". Advanced Materials Research 11-12 (luty 2006): 579–82. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.579.

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By overcoming less excitation efficiency of rare-earth ions due to small oscillator strength (∼10-6) of f-f transition, Eu3+ ions were intentionally introduced to nano-sized semiconductor of tin oxide (SnO2) in silica (SiO2)matrix via a sol-gel route. As a consequence, the excitation energy was significantly absorbed by the nano-sized SnO2 with controlled band-gap energy owing to quantum size effect (QSE) and subsequently transferred from nano-sized SnO2 to the Eu3+ ions doped, resulting in the enhancement of Eu3+ red emission (external quantum efficiency : 75.6 %).

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Al Shehri, Alya S., El Sayed Yousef i A. E. Al-Salami. "Raman-Scattering Properties of Er-Doped Alkaline Tellurite Glasses for Lasing Applications". Science of Advanced Materials 12, nr 6 (1.06.2020): 861–65. http://dx.doi.org/10.1166/sam.2020.3749.

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Alkaline tellurite glasses within composition of 65TeO2–9Nb2O5–5Li2O–15LiCl–5PbO–1.0La2O3 xEr2O3 ions doped (where x is 0, 20000, 25000 and 30000 ppm) have been prepared by the quenching melting method. Herein, parameters such as Judd–Ofelt, Ωt (t = 2, 4, 6) has been estimated. Transfer probabilities quality factors, magnetic and electric radiative oscillator strength fluorescence are used for a number of different excited states. Moreover, the structure of prepared glasses was investigated using Raman spectra. Physical and spectroscopic characterizations of Er3+ doped these glasses, which imply that we can fabricate them as potential candidates for optical application.

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Chen, Zhifan, i Alfred Z. Msezane. "Calculation of the singlet–triplet energy differences using the universal function". Canadian Journal of Physics 74, nr 5-6 (1.05.1996): 279–81. http://dx.doi.org/10.1139/p96-043.

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A method to calculate the singlet–triplet energy differences in electron–atom (molecule) scattering is developed. The method uses the recently developed universal function, which can extrapolate the generalized oscillator strength through the nonphysical region to K2 (momentum transfer squared) = 0, to calculate the integral of the energy difference in the small K2 region. Cubic spline is used for the experimental data to evaluate the contribution to the integral numerically. The energy differences in the transitions 11S–21,3P in e–He and X1 Σ+–A1,3 Π in e–CO scattering are calculated and compared with measurements as illustrative examples.

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CHAKHMAKHCHAYN, L., G. GRIGORYAN, C. LEROY, Y. PAHSAYAN-LEROY, S. GUERIN i H. R. JAUSLIN. "INFLUENCE OF UNEQUAL OSCILLATOR STRENGTHS ON STIMULATED RAMAN ADIABATIC PASSAGE THROUGH BRIGHT STATE". International Journal of Modern Physics: Conference Series 15 (styczeń 2012): 147–51. http://dx.doi.org/10.1142/s2010194512007076.

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In the present work an analytical and numerical analysis of the b -STIRAP process in a medium with unequal oscillator strengths is performed. It is shown that the length of population transfer can be considerably increased by an appropriate choice of the dipole transitions.

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Saleh, Akila A., i Robert J. Crutchley. "Solvent dependence of ligand to metal charge-transfer oscillator strength: outer-sphere perturbation of the ruthenium(III)-cyanamide bond". Inorganic Chemistry 29, nr 11 (maj 1990): 2132–35. http://dx.doi.org/10.1021/ic00336a019.

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Barriuso, M. T., J. A. Aramburu, C. Daul i M. Moreno. "A microscopic insight into oscillator strengths: The charge transfer bands for CuCl2-4". International Journal of Quantum Chemistry 61, nr 3 (1997): 563–70. http://dx.doi.org/10.1002/(sici)1097-461x(1997)61:3<563::aid-qua25>3.0.co;2-8.

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SZYMCZAK, H., L. GENZEL i A. WITTLIN. "BOUND SMALL POLARONS IN HIGH-Tc SUPERCONDUCTORS". International Journal of Modern Physics B 04, nr 07n08 (czerwiec 1990): 1369–78. http://dx.doi.org/10.1142/s0217979290000668.

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The thermal and acoustic anomalies in high-Tc superconductors are interpreted in terms of contributions arising from the tunneling motion of bound small polarons. The small polarons arise in YBa 2 Cu 3 O 7 oxides due to the localization of the holes on one of the four O 2− ions surrounding the Cu(2) site in the CuO2 plane. The optical absorption band located at 0.4 eV is explained as a light-induced transfer of holes between the equivalent O 2− sites. It is argued that the strong hole-lattice interaction is responsible for the enhanced oscillator strength of optical phonons in YBa 2 Cu 3 O 7.

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Khan, Naveed Ahmad, Muhammad Sulaiman, Jamel Seidu i Fahad Sameer Alshammari. "Investigation of Nonlinear Vibrational Analysis of Circular Sector Oscillator by Using Cascade Learning". Advances in Materials Science and Engineering 2022 (5.09.2022): 1–15. http://dx.doi.org/10.1155/2022/1898124.

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This paper analyzed the model of swinging oscillation of a solid circular sector arising in hydrodynamical machines, electrical engineering, heat transfer applications, and civil engineering. Nonlinear differential equations govern the mathematical model for frequency oscillation of the system. Furthermore, a computational strength of Cascade neural networks (CNNs) is utilized with backpropagated Levenberg–Marquardt (BLM) algorithm to study the oscillations in angular displacement θ , velocity θ ′ , and acceleration θ ″ . A data set for the supervised learning of the CNN-BLM algorithm for different angles α and radius R are generated by Runge–Kutta (RK-4) method. The BLM algorithm further interprets the dataset with log-sigmoid as an activation function for the solutions’ validation, testing, and training. The results obtained by the design scheme are compared with Akbari–Ganji’s (AG) method. The rapid convergence and quality of the solutions are validated through performance indicators such as mean absolute deviations (MAD), root means square error, and error in Nash–Sutcliffe efficiency (ENSE). The statistics demonstrate the design scheme’s applicability and efficiency to highly singular nonlinear problems.

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Di Sia, Paolo, i Valerio Dallacasa. "Weight Analysis in a Quantum Mechanical Transport Model for Nano and Bio Materials". Defect and Diffusion Forum 312-315 (kwiecień 2011): 620–25. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.620.

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The charge transport is one of the most important factors for the efficiency in nanostructured devices. The detailed nature of transport processes in these systems is still not completely resolved. Starting from the Drude model, we have proposed an analytical method for describing classically the most important quantities concerning transport phenomena, i.e. the velocity correlation functions, the mean square deviation of position and the diffusion coefficient. To fully account for quantum effects arising in systems of reduced dimensions, in this work we present the quantum mechanical version of this model, comprehending the oscillator strength weights, and apply the model to single-walled carbon nanotube ﬁlms, extracting the oscillator weights from reflectivity data reported in the literature. We are able to give a complete and precise description of time correlations avoiding time-consuming numerical or simulation procedures. This method demonstrates high generality and offers perspectives even in the study of ions, like mass transfer, and solutions, so as in nano bio systems. This quantum mechanical extension allows significant applications for the nanodiffusion in nanostructured, porous and cellular materials, as for biological, medical and nanopiezotronic devices.

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Crutchley, Robert J., Akila A. Saleh, Kierstan McCaw i Manuel A. S. Aquino. "The Dependence of Ligand to Metal Charge Transfer Oscillator Strength on the Nature of the Ruthenium (III)-Cyanamide Bond: Outersphere Perturbations". Molecular Crystals and Liquid Crystals 194, nr 1 (styczeń 1991): 93–101. http://dx.doi.org/10.1080/00268949108041154.

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WU, Yanming, Jiguo Shan, Zhi Li, Xinghua Wang, Yan Feng i Minglin Wang. "•Narrow Groove Laser-Arc Hybrid Welding of Thick-Sectioned HSLA Steel Using Laser Beam Oscillation". Welding Journal 101, nr 7 (1.07.2022): 181–96. http://dx.doi.org/10.29391/2022.101.014.

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In this study, a sine-oscillating laser was used to obtain narrow groove laser-arc hybrid welding (NGHW) of high-strength low-alloy (HSLA) steel. Then the effects of laser beam oscillation amplitude and space constraint on arc behavior, droplet transfer, weld geometry, and incomplete fusion of the weld beads were analyzed. Due to the minimum arc voltage principle and inherent arc self-regulation, when the laser did not oscillate, it was observed that the arc cathode spot was typically attached to one sidewall. As a result, the molten pool did not spread through the entire width of the gap , resulting in incomplete fusion. When the laser beam oscillated in a sinusoidal path, the energy density on both sides of the amplitude was higher than the centerline, and the aspect ratio of the weld decreased. The speed of the beam along the centerline was found to be much higher than the speed on both sides of the amplitude. The molten pool oscillated in the width direction under the action of the oscillating beam, forming a concave surface, which promoted melting of the sidewalls of the groove and suppressed incomplete fusion defects in the sidewalls. The technical feasibility of NGHW assisted by laser beam oscillation was verified using a 60-mm-thick weld, which was haracterized by a smooth layer transition and the absence of visible defects.

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Kavanagh, Maeve A., Joshua K. G. Karlsson, Jonathan D. Colburn, Laura M. C. Barter i Ian R. Gould. "A TDDFT investigation of the Photosystem II reaction center: Insights into the precursors to charge separation". Proceedings of the National Academy of Sciences 117, nr 33 (3.08.2020): 19705–12. http://dx.doi.org/10.1073/pnas.1922158117.

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Photosystem II (PS II) captures solar energy and directs charge separation (CS) across the thylakoid membrane during photosynthesis. The highly oxidizing, charge-separated state generated within its reaction center (RC) drives water oxidation. Spectroscopic studies on PS II RCs are difficult to interpret due to large spectral congestion, necessitating modeling to elucidate key spectral features. Herein, we present results from time-dependent density functional theory (TDDFT) calculations on the largest PS II RC model reported to date. This model explicitly includes six RC chromophores and both the chlorin phytol chains and the amino acid residues <6 Å from the pigments’ porphyrin ring centers. Comparing our wild-type model results with calculations on mutant D1-His-198-Ala and D2-His-197-Ala RCs, our simulated absorption-difference spectra reproduce experimentally observed shifts in known chlorophyll absorption bands, demonstrating the predictive capabilities of this model. We find that inclusion of both nearby residues and phytol chains is necessary to reproduce this behavior. Our calculations provide a unique opportunity to observe the molecular orbitals that contribute to the excited states that are precursors to CS. Strikingly, we observe two high oscillator strength, low-lying states, in which molecular orbitals are delocalized over ChlD1and PheD1as well as one weaker oscillator strength state with molecular orbitals delocalized over the P chlorophylls. Both these configurations are a match for previously identified exciton–charge transfer states (ChlD1+PheD1−)* and (PD2+PD1−)*. Our results demonstrate the power of TDDFT as a tool, for studies of natural photosynthesis, or indeed future studies of artificial photosynthetic complexes.

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Watanabe, Noboru, i Masahiko Takahashi. "Theoretical study of generalized oscillator strengths for the low-lying electronic excitations of CH₃Cl and CF₃Cl". Journal of Physics B: Atomic, Molecular and Optical Physics 55, nr 1 (5.01.2022): 015201. http://dx.doi.org/10.1088/1361-6455/ac4a22.

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Abstract We report a theoretical study of electronic excitation in CH3Cl and CF3Cl by electron impact. Momentum-transfer-dependent generalized oscillator strengths (GOSs) are calculated for transitions to low-lying excited singlet-states at the equation-of-motion coupled-cluster singles and doubles level. The influence of molecular vibration is taken into account in the calculation. The theoretical results show reasonable overall agreement with experimental data reported in the literature. The shapes of the GOS profiles reveal that the 1 1E state of CH3Cl has a valence-Rydberg mixed nature, while that of CF3Cl is of a predominant C–Cl antibonding character. A comparison with the experimental GOSs of CH3Cl provides unambiguous evidence that the 3pe state is lower in energy than the 3pa1 state. Optical oscillator strengths are also calculated and comparison is made with available experimental and other theoretical results.

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Machado, Paulo César Miranda, Francisco Aparecido Pinto Osório i Antônio Newton Borges. "Inter-subband structure factor for a quasi-one-dimensional polaron gas". International Journal of Modern Physics B 30, nr 30 (23.11.2016): 1650218. http://dx.doi.org/10.1142/s0217979216502180.

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In this work, the collective excitation spectra of quasi-one-dimensional plasmon in a rectangular GaAs quantum wire is investigated. Our calculations are performed within the Singwi, Tosi, Land and Sjölander (STLS) self-consistent theory taking into account the plasmon–longitudinal optical (LO) phonon coupling effects. We have employed a three subband model with only the first subband occupied by electrons and we have considered intra-subband and inter-subband transitions. We show that the polaronic effects cause the appearance of dips and oscillations in the static structure factor dispersion relation, which are directly related with the oscillator strength transfer between the collective excitation energy branches. We have also observed oscillations in the pair-correlation function that are characteristic of inter-subband transitions and it denotes partial localization of the particle.

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Cohen, A. J., i L. N. Makar. "Dynamic biaxial absorption spectra of Ti3+ and Fe2+ in a natural rose quartz crystal". Mineralogical Magazine 49, nr 354 (grudzień 1985): 709–15. http://dx.doi.org/10.1180/minmag.1985.049.354.10.

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AbstractThe absorption spectrum of Ti3+ in quartz is typical for that element in an octahedral site, except for the high oscillator strength of the band which indicates intensive charge transfer, most likely between a substitutional Ti4+ and an interstitial Ti3+. The biaxial anisotropy of the band is similar to that of octahedral Fe2+ in the same crystal, suggesting the same site for the Ti3+, an interstitial site at the intersection of the threefold axis with two twofold axes. The dynamic nature of the Ti and Fe ions is indicated when the crystal is subjected to X-irradiation and then to bleaching treatment with UV-light or heat. Ti(IV) ions are acceptors of electrons donated by Fe2+ during X-irradiation. This is indicated by increase of the 2.4 eV band intensity with decrease in the Fe2+ band intensities and appearance of Fe3+ charge transfer bands in the UV-region. Heat and UV-light treatment decrease the Fe3+ CT bands and increase the Fe2+ crystal-field bands along with decrease in the 2.4 eV band related to titanium.

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30

Mostafa, Gamal A. E., Tarek A. Yousef, Samir T. Gaballah, Atef M. Homoda, Rashad Al-Salahi, Haya I. Aljohar i Haitham AlRabiah. "Quinine Charge Transfer Complexes with 2,3-Dichloro-5,6-Dicyano-Benzoquinone and 7,7,8,8-Tetracyanoquinodimethane: Spectroscopic Characterization and Theoretical Study". Applied Sciences 12, nr 3 (18.01.2022): 978. http://dx.doi.org/10.3390/app12030978.

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The molecular charge transfer reactions of quinine (Q) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a π-acceptor to form charge transfer (CT) complexes have been studied. The CT complexes were characterized by infrared spectra, NMR, mass spectrometry, conductometry and spectrometry. The Q-DDQ and Q-TCNQ charge transfer complexes were monitored at 480 and 843 nm, respectively. The results confirm the formation of CT complexes. The molar ratio of Q:DDQ and Q: TCNQ assessed using Job’s method was 1:1, which agrees with the results obtained by the Benesi-Hildebrand equation. The stability of the formed CT complexes was assessed by measuring different spectroscopic parameters such as oscillator strength, transition dipole moment, ionization potential, the energy of CT complex, resonance energy, dissociation energy and standard free energy change. The DFT geometry optimization of quinine, DDQ and TCNQ, its charge transfer complex, and UV theoretical vs. experimental comparative study were carried out. The theoretical and experimental results agreed. DFT/B3LYP/6-311++G(d,p) level of theory was used for the investigation of charge transfer between quinine as electron donor and (DDQ and TNCQ) as electron acceptors. The geometric structures, orbital energies, HOMO, LUMO and energy gaps were determined. The transition energies of the charge transfer complexes were computed using the TD-DFT/B3LYP/6-311++G(d,p) level of theory. The computed parameters were comparable to the experimental parameters, and the computational results aided in the analysis of the data.

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31

El Bakri, Youness, Malahat Kurbanova, Atazaz Ahsin, Nacaf Ramazanzade i Rashad Al-Salahi. "A Probe to Surface Reactivity, Crystal Structure, and DFT Investigations for Newly Synthesized 4,5-bis(4-Nitrophenyl)-8a-phenyl-decahydro-[1,3]diazino[4,5-d]pyrimidine-2,7-dione: A Combined Theoretical and Experimental Study". Crystals 13, nr 6 (11.06.2023): 942. http://dx.doi.org/10.3390/cryst13060942.

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The multicomponent reaction of 4-nitrobenzaldehyde with acetophenone and urea in the presence of HCl was investigated, and, as a result, 4,5-bis(4-nitrophenyl)-8a-phenyl-decahydro-[1,3]diazino[4,5-d]pyrimidine-2,7-dione was synthesized. The structure of the synthesized compound was confirmed by the X-ray method. We performed Hirshfeld surfaces (HS) analysis and two-dimensional (2D) fingerprint plots for the studied compound to obtain surface reactivity and intermolecular interactions. The H∙∙∙H interactions were found to be higher, up to 32.2%, while the percentage C∙∙∙O contact was found to be the lowest among the reported interactions for single crystal packing. The energy framework analysis shows the strength of interaction energy within fragments of a single crystal at 3.08 A distances. The DFT study shows structural reactivity and a reduced HOMO-LUMO gap up to 4.0 eV. The NPA study reveals the reactivity and excellent charge transfer within the structure. The TD-DFT study reveals the absorbance in the UV region and excited state parameters during crucial transitions (transitions with maximum oscillator strength). The investigated compound shows excellent optical and nonlinear optical (NLO) properties, as indicated by its polarizability (αo) and hyperpolarizability (βo) values.

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32

Qiao, Wei, Hao Sun, Xiaoyue Fan, Meiling Jin, Haiyang Liu, Tianhong Tang, Lei Xiong, Binghui Niu, Xiang Li i Gang Wang. "Interlayer Coupling and Pressure Engineering in Bilayer MoS2". Crystals 12, nr 5 (12.05.2022): 693. http://dx.doi.org/10.3390/cryst12050693.

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Controlling the interlayer coupling by tuning lattice parameters through pressure engineering is an important route for tailoring the optoelectronic properties of two-dimensional materials. In this work, we report a pressure-dependent study on the exciton transitions of bilayer MoS2 exfoliated on a diamond anvil surface. The applied hydrostatic pressure changes from ambient pressure up to 11.05 GPa using a diamond anvil cell device. Raman, photoluminescence, and reflectivity spectra at room temperature are analyzed to characterize the interlayer coupling of this bilayer system. With the increase of pressure, the indirect exciton emission disappears completely at about 5 GPa. Importantly, we clearly observed the interlayer exciton from the reflectivity spectra, which becomes invisible at a low pressure around 1.26 GPa. This indicates that the interlayer exciton is very sensitive to the hydrostatic pressure due to the oscillator strength transfer from the direct transition to the indirect one.

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33

Hayatdavoodi, Masoud, Yongbo Chen, Binbin Zhao i R. Cengiz Ertekin. "Experiments and computations of wave-induced oscillations of submerged horizontal plates". Physics of Fluids 35, nr 1 (styczeń 2023): 017121. http://dx.doi.org/10.1063/5.0132569.

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Wave-induced oscillations of submerged horizontal plates are studied by conducting laboratory experiments and by developing theoretical and computational models. These models include a linear solver based on the Green-function method, a nonlinear model based on Green–Naghdi wave equations, and a model based on computational fluid dynamics. The submerged horizontal plate oscillates in the vertical direction due to oscillatory wave loads. Oscillations of the plate are controlled by the use of a spring-damper system. Laboratory measurements and the models provide quantitative information on (i) how oscillations of submerged plates vary with wave conditions, plate characteristics, and the control system and (ii) how different models using different levels of assumptions predict the wave-induced oscillations. Particular attention is given to energy-production applications of the submerged oscillating plate, and discussion is provided on how the oscillation height and velocity vary with its initial submergence depth, stiffness of the attached spring, and the strength of the viscous damper. It is found that the oscillation varies almost linearly with the wave height, but nonlinearly with the wave period, initial submergence depth of the plate, damping, and the spring stiffness. Overall, it is found that nonlinearity plays an important role in this problem, while the effect of viscosity is negligible.

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34

Chinnusamy, Saravanan, Nasrin I. Shaikh i Milind S. Dangate. "Impact of t-butyl group on the singlet–triplet energy gap via weak orbital overlap of [1,2,5]-thiadiazolo[3,4-C] pyridine-based TADF emitters: Structural modification". Journal of Theoretical and Computational Chemistry 17, nr 07 (listopad 2018): 1850048. http://dx.doi.org/10.1142/s0219633618500487.

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We theoretically investigated the combination of D-A and D-spacer (phenyl ring)-A with an electron donating alkyl (t-butyl) group. The strategy of twisting the geometry of the molecule with the alkyl substituents exclusion of strong electron-withdrawing or -donating groups leads to gain efficient deep blue-to-blue thermally activated delayed fluorescence (TADF) emitter through maintaining the band gap while the reduction of singlet-triplet energy gap ([Formula: see text]. The t-butyl group strongly twisted the conformation of molecules by the steric hindrance, which resulted in weak highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) overlap ([Formula: see text] and efficient spatial separation of HOMO and LUMO ([Formula: see text] in the [Formula: see text] state. In contrast, designed molecules [Formula: see text] state own large HOMO and LUMO overlap of excited singlet state ([Formula: see text] and inefficient spatial separation of HOMO and LUMO. The computed results indicated that introducing alkyl group into the phenyl ring of the acceptor of the designed molecules cannot affect the [Formula: see text]. The [Formula: see text] is mainly related to the [Formula: see text], which can be adjusted by tuning the orbital [Formula: see text]. The large modular orbital overlap at [Formula: see text] and [Formula: see text] excited states resulted in large [Formula: see text], which occurs in the range of 0.38–0.59[Formula: see text]eV whose dominant contribution switches from charge transfer to local excitation. Our studied results reiterate (10.1038/srep10923) that modular orbital overlap of [Formula: see text], HOMO and LUMO overlap of excited triplet state [Formula: see text], spatial separation of HOMO and LUMO in the excited singlet state ([Formula: see text], and spatial separation of HOMO and LUMO in the excited triplet state ([Formula: see text] are the essential factors to determine [Formula: see text] when inconsistencies between [Formula: see text] and [Formula: see text] exist. Increasing the dihedral angle between [Formula: see text] and [Formula: see text] from molecules 1–4 (9–12) decreases the transition dipole moment, which lowers the oscillator strength. When changing the connection position between [Formula: see text] and [Formula: see text], molecules 5–8, the oscillator strength reduced to half with respect to molecules 1–4 and 9–12. The present work provides a theoretical understanding of the impact of alkyl substituents on the overlap of HOMO–LUMO resulting to tuning the [Formula: see text], as well as its influence on the oscillator strength, which may be a reliable idea to design efficient TADF emitters.

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35

WANG, BO-CHENG, i CHIN-KUEN TAI. "DFT-PCM STUDIES OF THE SOLVENT EFFECTS ON THE ABSORPTION PROPERTIES OF DCM". Journal of Theoretical and Computational Chemistry 05, nr 04 (grudzień 2006): 957–65. http://dx.doi.org/10.1142/s0219633606002672.

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In this paper, we have performed the optimized structures of the red emitting material, 4-(dicyanomethylene)-2-methyl-6-[p-(dimethyl amino) styryl]-4H-pyran (DCM), with different polarity solvent environments by using the density functional theory (DFT) method, B3LYP/6-31G*. The time-dependent density functional theory (TD-DFT) and the polarizable continuum model (PCM) have been used to obtain the optical properties in the solvent environment. It has been observed that when the solvent polarity increases, the DCM molecule exhibits the red shift in the maximum absorption wavelength [Formula: see text] and enhances the oscillator strength (f). The solvent polarity also enhances the electron transfer ability from the electron-donating dimethylamine group (-N(CH3)2) to the electron-withdrawing =C(CN)2 group. The S 0 → S 1 transition of DCM is found to be π–π*. The maximum absorption wavelengths [Formula: see text] of different solvent environments are found to be consistent with the reported experimental results.

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36

Goud, K., Ch Ramesh i B. Appa Rao. "Upconversion and Spectroscopic Properties of Rare Earth Codoped Lead Borate Glass Matrix". Material Science Research India 14, nr 2 (12.09.2017): 140–45. http://dx.doi.org/10.13005/msri/140209.

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To develop efficient upconversion laser materials in the visible region an active lead borate glasses doped with Er3+/Yb3+ rare earth ions (GEY) has been studied extensively. In this investigation characterization techniques like Optical absorption, FTIR and photoluminescence were recorded and the data was analyzed. To evaluate the values of Ω2, Ω4 and Ω6 Judd-Ofelt theory has been applied to the f ↔ f transitions. Based on Judd–Ofelt theory branching ratio (βr) oscillator strength and the radiative life time (τR) values were determined. The upconversion spectra exhibited three emission bands at around 525 nm (2H11/2 ® 4I15/2), 545 nm (4S3/2 ® 4I15/2) and 660 nm (4F9/2 ® 4I15/2). The energy transfer mechanism between Yb3+ and Er3+ was discussed very clearly. Comparing the data obtained in other Er3+/Yb3+ doped materials, the lead bismuth gallium borate glasses doped with 0.6 mol% of Er2O3/0.2 mol% of Yb2O3 ions are suitable materials for developing red upconversion lasers in the visible region.

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37

Lu, Xiaoqing, Shuxian Wei, Chi-Man Lawrence Wu, Ning Ding, Shaoren Li, Lianming Zhao i Wenyue Guo. "Theoretical Insight into the Spectral Characteristics of Fe(II)-Based Complexes for Dye-Sensitized Solar Cells—Part I: Polypyridyl Ancillary Ligands". International Journal of Photoenergy 2011 (2011): 1–11. http://dx.doi.org/10.1155/2011/316952.

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The design of light-absorbent dyes with cheaper, safer, and more sustainable materials is one of the key issues for the future development of dye-sensitized solar cells (DSSCs). We report herein a theoretical investigation on a series of polypyridyl Fe(II)-based complexes of FeL2(SCN)2, [FeL3]2+, [FeL′(SCN)3]-, [FeL′2]2+, and FeL′′(SCN)2(L = 2,2′-bipyridyl-4,4′-dicarboxylic acid, L′ = 2,2′,2″-terpyridyl-4,4′,4″-tricarboxylic acid, L″= 4,4‴-dimethyl-2,2′ : 6′,2″ :6″,2‴-quaterpyridyl-4′,4″-biscarboxylic acid) by density functional theory (DFT) and time-dependent DFT (TD-DFT). Molecular geometries, electronic structures, and optical absorption spectra are predicted in both the gas phase and methyl cyanide (MeCN) solution. Our results show that polypyridyl Fe(II)-based complexes display multitransition characters of Fe → polypyridine metal-to-ligand charge transfer and ligand-to-ligand charge transfer in the range of 350–800 nm. Structural optimizations by choosing different polypyridyl ancillary ligands lead to alterations of the molecular orbital energies, oscillator strength, and spectral response range. Compared with Ru(II) sensitizers, Fe(II)-based complexes show similar characteristics and improving trend of optical absorption spectra along with the introduction of different polypyridyl ancillary ligands.

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38

BEDNARZ, M., i J. P. LEMAISTRE. "DISORDER-INDUCED RELAXATION OF FRENKEL EXCITONS IN MOLECULAR AGGREGATES". International Journal of Modern Physics B 15, nr 28n30 (10.12.2001): 3761–64. http://dx.doi.org/10.1142/s0217979201008603.

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A model, based on the intraband scattering of excitons in one-dimensional J-aggregates is proposed to describe the lengthening of the experimentally observed radiative lifetime with temperature. According to this mechanism, the exciton-phonon scattering transfers the oscillator strength fromt he lowest k≅0 optically allowed state to the other states within the excitonic band. A Pauli master equation, in which the hopping rates are calculated, is used to describe the thermalization of the excitonic band. Assuming a fast relaxation mechanism, the temperature dependence of the exciton radiative lifetime is simulated for various chain lengths.

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39

Rahman, A. F. M. Motiur, Ahmed H. Bakheit, Shofiur Rahman, Gamal A. E. Mostafa i Haitham Alrabiah. "Procainamide Charge Transfer Complexes with Chloranilic Acid and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone: Experimental and Theoretical Study". Processes 11, nr 3 (27.02.2023): 711. http://dx.doi.org/10.3390/pr11030711.

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The formation of charge transfer (CT) complexes between bioactive molecules and/or organic molecules is an important aspect in order to understand ‘molecule-receptor’ interactions. Here, we have synthesized two new CT complexes, procainamide-chloranilic acid (PA-ChA) and procainamide-2,3-dichloro-5,6-dicyano-1,4-benzoquinone (PA-DDQ), from electron donor procainamide (PA), electron acceptor chloranilic acid (ChA), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The structures of these two CT complexes were elucidated/characterized using FTIR, NMR, and many other spectroscopic methods. A stability study of each complex was conducted for the first time using various spectroscopic parameters (e.g., formation constant, molar extinction coefficient, ionization potential oscillator strength, dipole moment, and standard free energy). The formation of CT complexes in solution was confirmed by spectrophotometric determination. The molecular composition of each complex was determined using the spectrophotometric titration method and gave a 1:1 (donor:acceptor) ratio. In addition, the formation constant was determined using the Benesi–Hildebrand equation. To understand the noncovalent interactions of the complexes, density functional theory (DFT) calculations were performed using the ωB97XD/6-311++G(2d,p) level of theory. The DFT-computed interaction energies (ΔIEs) and the Gibbs free energies (ΔGs) were in the same order as observed experimentally. The DFT-calculated results strongly support our experimental results.

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40

Koput, J., B. Marciniak i S. Paszyc. "Protonation of the Trimethylated Pyrichrominium Ion". Zeitschrift für Naturforschung A 41, nr 4 (1.04.1986): 661–64. http://dx.doi.org/10.1515/zna-1986-0411.

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pKSpectroscopic manifestations of protonation of the trimethylated pyrichrominium ion studied previously experimentally [1] are investigated using a semiempirical INDO/S Cl method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with experimental spectra. Calculated charge densities on nitrogen atoms are correlated with experimental values for the ground and lowest excited singlet and triplet states. The possibility of the proton transfer reaction (phototautomerization) in the lowest excited singlet state of monoprotonated species is discussed on the basis of INDO/S Cl calculations, fluorescence and absorption spectroscopy.

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41

Polacki, Zenon, i Janusz Rak. "Theoretical Approach in Explanation of Energy Donor Properties of 1,4-Dioxane and 1,4-Dioxane-Water Complexes". Zeitschrift für Naturforschung A 43, nr 7 (1.07.1988): 621–26. http://dx.doi.org/10.1515/zna-1988-0702.

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Abstract The CNDO/2 CI method was used for the examination of 1,4-dioxane and 1,4-dioxane-water complexes (2:1), taking into account various conformations of the dioxane molecule. The energies of the molecules in the ground and excited states, the energies of hydrogen bond formation, the dipole moments, the transition moments, and the oscillator strengths for both the complexed and isolated 1,4-dioxane molecules were evaluated. The results of these studies are used to reveal the influence of water on the features of energy transfer from excited, by y-radiation, 1,4-dioxane or dioxane-water complexes to the luminophor.

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42

Rangarajan, K. E., i D. Mohan Rao. "Parametric Study of Molecular Line Polarization in the Solar Atmosphere". International Astronomical Union Colloquium 179 (2000): 269. http://dx.doi.org/10.1017/s0252921100064654.

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Extended AbstractThe polarimetric observations of the quiet sun show linear polarization in molecular lines of C2, MgH, etc. The molecular lines are very faint in the intensity spectrum. Q branch transitions of MgH are considered in this study. Using radiative transfer calculations, we find that the intensity and polarization profiles of MgH lines can be matched for a range of inelastic collisional rates (ΓI) and depolarizing elastic collision rates (D(2)) of the transitions in solar atmosphere. It is shown that the physical constraints imposed on these parameters can be used to estimate them. This procedure also allows us to get the oscillator strength (f). It is found for the strong line 5156.652 Å,f= 0.12, ΓI, = 5.59 × l07sec−1andD(2)= 1.29 × 108sec−1. Most of the other lines observed are weak by a factor of 3 in intensity compared to the 5156.652 Å line but show a polarization value of the order of 0.08%. One such typical line is 5156.997 Å. This line can be fitted for the parametersf= 0.04, ΓI, = 1.22 × 107sec−1andD(2)= 2.95 × 107sec−1.

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GOLINEY, IGOR, i VOLODYMYR SUGAKOV. "RARE GAS PRECIPITATES IN METALS AS QUANTUM DOTS FOR THE POLARITONS". International Journal of Modern Physics B 15, nr 28n30 (10.12.2001): 3685–89. http://dx.doi.org/10.1142/s0217979201008433.

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Energy spectra of the size quantization of excitons in Xe, Kr, Ar and Ne precipitates in Al and their manifestation in reflection spectra are calculated taking into account polariton effects (dipole-dipole exciton interactions), spatial dispersion and mixing of the electronic excitations of the inclusion with collective excitations of the surrounding metal (plasmons). It was shown that: 1) the proximity of energies of the exciton levels and the plasmons localized on the inclusion (surface plasmons) results in the gigantic shift (up to 1 eV) of the levels of coupled excitations, 2) the transfer of the oscillator strength from the plasmon level to the exciton levels leads to the amplification of optical transitions in bubbles by several orders of magnitude. Depending on the position of the surface polariton with respect to the surface plasmon the spectra either show additional broadenning due to the coupling with quantized exciton levels (Ar, Ne) or the polariton level is pushed out of the exciton band and manifests itself as a narrow dip in the reflection spectra.

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44

Flittner, Rudolf, i Michal Přibyl. "Computational fluid dynamics model of rhythmic motion of charged droplets between parallel electrodes". Journal of Fluid Mechanics 822 (6.06.2017): 31–53. http://dx.doi.org/10.1017/jfm.2017.230.

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A mathematical model of rhythmic motion of a charged droplet between two parallel electrodes is developed in this study. The work is motivated by recent experimental findings that report oscillatory behaviour of water in oil droplets under a direct current electric field. The model considers the presence of a charged droplet placed in a dielectric medium. The droplet is immediately attracted to the electrode with the opposite polarity. When approaching the electrode, the electric charge is electrochemically reversed within the droplet, which is then repelled to the other electrode. The entire process can periodically repeat. The model is able to track a deformable liquid–liquid interface, the dynamics of the wetting process at the electrodes and the dynamics of electrochemical charge transfer between the droplet and the electrodes. The dependences of the oscillation frequency, charge acquired by the droplet and charging time on several model parameters (surface charge density on electrodes, kinetic parameter of charging, droplet–electrode contact angle, droplet size, liquid permittivity) are examined. Qualitative agreement of the model predictions with available experimental data is obtained, e.g. the oscillation frequency increases with growing electric field strength or droplet size. Our model represents the first successful attempt to predict oscillatory motion of aqueous droplets by a pseudo-three-dimensional two-phase approach. Our model also strongly supports the theory that the oscillatory motion relies on the combination of electrochemical charge injection at the electrodes and electrostatic attraction/repulsion processes.

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Dey, Indrakshi, i Nicola Marchetti. "Channel Emulator Framework for Underwater Acoustic Communications". Applied Sciences 13, nr 9 (8.05.2023): 5818. http://dx.doi.org/10.3390/app13095818.

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In this paper, we develop a tractable mathematical model and an emulation framework for communicating information through water using acoustic signals. Water is considered one of the most complex media to model due to its vastness and variety of characteristics, which depend on the scenario, the type of water body (lakes, rivers, tanks, sea, etc.), and the geographical location of the water body being considered. Our proposed mathematical model involves the concept of damped harmonic oscillators to represent the medium (water); Milne’s oscillator technique is used to map the interaction between the acoustic signal and water. Wave equations formulated for acoustic pressure and acoustic wave velocity are employed to characterise the travelling acoustic signal. The signal strength, phase shift, and time delay generated from the mathematical model are then inputted into a Simulink-based emulator framework to generate channel samples and channel impulse responses. The emulator utilises the wide sense stationary uncorrelated scattering (WSSUS) assumption and a finite sum-of-sinusoids (SOS) approach with a uniformly distributed phase to generate the channel samples. By utilising this emulator platform, it becomes feasible to generate profiles for amplitude variation, the Doppler shift, and spread experienced by any travelling signal in various underwater communication scenarios. Such a platform can be employed to simulate different communication scenarios, underwater network topologies, and data for training various learning models. Additionally, it can predict the performance of different modulation, multiplexing, error correction, and multi-access techniques for underwater acoustic communication (UWAC) systems.

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Turci, Cassia C., Stephen G. Urquhart i Adam P. Hitchcock. "Inner-shell excitation spectroscopy of aniline, nitrobenzene, and nitroanilines". Canadian Journal of Chemistry 74, nr 6 (1.06.1996): 851–69. http://dx.doi.org/10.1139/v96-094.

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Oscillator strengths for C 1s, N 1s, and O 1s excitation spectra of aniline, nitrobenzene, and the isomeric nitroanilines have been derived from inner-shell electron energy loss spectroscopy recorded under low momentum transfer conditions (> 2.5 keV impact energy and small scattering angle, θ ≤ 2°). Extended Hückel Molecular Orbital (EHMO) calculations carried out within the equivalent core analogy are used to aid spectral interpretation. These spectra are used to investigate the sensitivity of core excitation spectroscopy to charge transfer interactions in aromatic molecules that have both electron-donating and electron-withdrawing substituents. Strong multielectron excitation features were not found, although these had been anticipated from photoemission studies. The C 1s → π* and N 1s (NH2) → π* spectral features of the nitroanilines are found to be strongly dependent on the substitution pattern (ortho, meta, or para). Key words: electronic structure, inner-shell excitation, nitroanilines, EHMO calculations.

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BAI, CHUNXU, JUNTAO WANG, JING ZHANG i YANLING YANG. "CONDUCTANCE IN GRAPHENE-BASED STRUCTURE WITH THE SPATIALLY-MODULATED STRENGTH OF SPIN–ORBIT INTERACTIONS". International Journal of Modern Physics B 25, nr 23n24 (30.09.2011): 3199–209. http://dx.doi.org/10.1142/s021797921110179x.

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Based on the transfer-matrix method, the transport properties of electrons in the multilayers structure with the spatially-modulated strength of spin–orbit interactions (SOIs) have been investigated. We show that the transmission and the conductance oscillate with the parameters of the structure and the incident energy. In particular, when only the Rashba spin–orbit interaction (RSOI) exists, in sharp contrast to its counterpart in conventional junctions, the minima of the normal transmission probabilities just reach a constant value 0.5.

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48

Yang, Lei. "Pinning Effect on Current-Induced Domain Wall Motion in Nanostrip". East Asian Journal on Applied Mathematics 7, nr 4 (listopad 2017): 837–51. http://dx.doi.org/10.4208/eajam.181016.300517d.

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AbstractPinning effect on current-induced magnetic transverse domain wall dynamics in nanostrip is studied for its potential application to new magnetic memory devices. In this study, we carry out a series of calculations by solving generalized Landau-Lifshitz equation involving a current spin transfer torque in one and two dimensional models. The critical current for the transverse wall depinning in nanostrip depends on the size of artificial rectangular defects on the edges of nanostrip. We show that there is intrinsic pinning potential for a defect such that the transverse wall oscillates damply around the pinning site with an intrinsic frequency if the applied current is below critical value. The amplification of the transverse wall oscillation for both displacement and maximum value of m3 is significant by applying AC current and current pulses with appropriate frequency. We show that for given pinning potential, the oscillation amplitude as a function of the frequency of the AC current behaves like a Gaussian distribution in our numerical study, which is helpful to reduce strength of current to drive the transverse wall motion.

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Tang, H. J., K. C. Tan i Weinian Zhang. "Analysis of Cyclic Dynamics for Networks of Linear Threshold Neurons". Neural Computation 17, nr 1 (1.01.2005): 97–114. http://dx.doi.org/10.1162/0899766052530820.

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The network of neurons with linear threshold (LT) transfer functions is a prominent model to emulate the behavior of cortical neurons. The analysis of dynamic properties for LT networks has attracted growing interest, such as multistability and boundedness. However, not much is known about how the connection strength and external inputs are related to oscillatory behaviors. Periodic oscillation is an important characteristic that relates to nondivergence, which shows that the network is still bounded although unstable modes exist. By concentrating on a general parameterized two-cell network, theoretical results for geometrical properties and existence of periodic orbits are presented. Although it is restricted to two-dimensional systems, the analysis can provide a useful contribution to analyze cyclic dynamics of some specific LT networks of high dimension. As an application, it is extended to an important class of biologically motivated networks of large scale: the winner-take-all model using local excitation and global inhibition.

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Omage, Folorunsho Bright, Cláudia S. Oliveira, Laura Orian i Joao Batista Teixeira Rocha. "Integrating Diphenyl Diselenide and Its Mehg+ Detoxificant Mechanism on a Conceptual DFT Framework". Chemistry Proceedings 2, nr 1 (9.11.2020): 26. http://dx.doi.org/10.3390/eccs2020-07577.

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Methylmercury (MeHg+) is an important environmental contaminant and its toxicity is associated with its interaction with selenium (e.g., selenol groups of selenoproteins or HSe−, which is the pivotal metabolite for Se incorporation into selenoproteins). We hypothesized that (PhSe)2 mediated MeHg+ detoxification could be indirectly altered by its open or closed conformation. The two conformations of (PhSe)2 were located on the potential energy surface (PES) computed at ZORA-OPBE-D3(BJ)/ZORA-def2-TZVP level of theory. HPLC analysis indicated that (PhSe)2 did not react with MeHg+, but its reduced intermediate formed a stable complex with MeHg+. The nudged elastic band (NEB) method revealed conformational changes from closed to open state with an H− (2 electrons) transfer from NaBH4, forming a reactant complex-like transition state (TS). The UV-Vis spectrophotometer used in combination with the time-dependent density functional theory (TD-DFT) indicated that the signal of (PhSe)2 at 239 nm was possibly the open conformer’s signal with oscillator strength 0.1 and a π → π * electron transfer character. The experimental band gap energy of (PhSe)2 at 5.20 eV matched to the excitation energy of the open conformation. The local softness (S−) on the selenium atoms almost doubles, as state changes from closed to open. The theoretical results have indicated that the open conformation of (PhSe)2 is likely the one that reacts with NaBH4 to form the PhSeH, which can react with MeHg+.

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