Lithuanian Journal of Physics最新文献

Optical characteristics of structures with silicon nanowires and metal nanoparticles 硅纳米线和金属纳米颗粒结构的光学特性

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2024-02-23 DOI: 10.3952/physics.2024.64.1.4

O. Havryliuk, O. Tkachuk, M. Terebinska, O. Semchuk, A. Biliuk

引用次数: 0

Second-order Rayleigh–Schrödinger perturbation theory for the GRASP2018 package: Core–valence correlations 用于 GRASP2018 软件包的二阶瑞利-薛定谔微扰理论：核价相关性

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2024-02-23 DOI: 10.3952/physics.2024.64.1.3

G. Gaigalas, P. Rynkun, L. Kitovienė

{"title":"Second-order Rayleigh–Schrödinger perturbation theory for the GRASP2018 package: Core–valence correlations","authors":"G. Gaigalas, P. Rynkun, L. Kitovienė","doi":"10.3952/physics.2024.64.1.3","DOIUrl":"https://doi.org/10.3952/physics.2024.64.1.3","url":null,"abstract":"\u0000 \u0000 \u0000The General Relativistic Atomic Structure package [GRASP2018, C. Froese Fischer, G. Gaigalas, P. Jönsson, and J. Bieroń, Comput. Phys. Commun. (2019), DOI: 10.1016/j.cpc.2018.10.032] is based on multiconfiguration Dirac– Hartree–Fock and relativistic configuration interaction (RCI) methods for energy structure calculations. The atomic state function used in the program is built from the set of configuration state functions (CSFs). The valence–valence, core–valence and core–core correlations are explicitly included through expansions over CSFs in RCI. We present a combination of RCI and the stationary second-order Rayleigh–Schrödinger many-body perturbation theory in an irreducible tensorial form to account for electron core–valence correlations when an atom or ion has any number of valence electrons. This newly developed method, which offers two ways of use, allows a significant reduction of the CSF space for complex atoms and ions. We also demonstrate how the method and program works for the energy structure calculation of Cl III ion. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140437627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The XYZ model in the mean-field approximation in terms of Pauli spin matrices 从保利自旋矩阵看平均场近似的 XYZ 模型

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2024-02-23 DOI: 10.3952/physics.2024.64.1.1

E. Albayrak

引用次数: 0

New approach to evaluating the thermodynamic consistency of melts in the ‘metal-slag’ system based on interatomic interaction parameters 基于原子间相互作用参数评估 "金属-熔渣 "体系熔体热力学一致性的新方法

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2024-02-23 DOI: 10.3952/physics.2024.64.1.6

D. Togobitska, A. Belkova

{"title":"New approach to evaluating the thermodynamic consistency of melts in the ‘metal-slag’ system based on interatomic interaction parameters","authors":"D. Togobitska, A. Belkova","doi":"10.3952/physics.2024.64.1.6","DOIUrl":"https://doi.org/10.3952/physics.2024.64.1.6","url":null,"abstract":"\u0000 \u0000 \u0000The article presents a new approach to evaluating the thermodynamic state of the ‘metal–slag’ system during metal smelting in oxidizing-reducing conditions. The interaction between the metal and slag is analyzed using the model of the structure of metallurgical melts, which considers cooperative ion exchange processes and interatomic interaction parameters. As a result of analyzing experimental data on the compositions of reacting melts during pig iron and steel smelting, criteria were developed for assessing the degree of achieving the equilibrium in the system regarding sulfur. The charge state parameters of the metallic system ZY and the slag system Δe, the slag stoichiometry index ρ, and the charge state parameter of the melt components Zi were used. The regularity of a consistent formation of metallic and slag melts has been established, which is evidenced by a significant correlation between the chemical equivalent of the metal composition ZY and the slag Δe. Analytical dependences were obtained in the form of ZY = f (Δe, ρ). The identified patterns and criteria can be integrated into automated process control systems for regulating the slag regime and producing high-quality pig iron and steel. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140436096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Predicting nonradiative decay barrier of BODIPY dye in polar environment by applying ONIOM multiscale method 应用 ONIOM 多尺度方法预测极地环境中 BODIPY 染料的非辐射衰减屏障

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2024-02-23 DOI: 10.3952/physics.2024.64.1.2

D. Narkevičius, S. Toliautas

{"title":"Predicting nonradiative decay barrier of BODIPY dye in polar environment by applying ONIOM multiscale method","authors":"D. Narkevičius, S. Toliautas","doi":"10.3952/physics.2024.64.1.2","DOIUrl":"https://doi.org/10.3952/physics.2024.64.1.2","url":null,"abstract":"\u0000 \u0000 \u0000Fluorescent molecular sensors are widely used in biological research. They allow straightforward viscosity, temperature or polarity measurements at the microscopic level, including live cells. Maps of desired physical properties can be obtained by applying fluorescence lifetime imaging microscopy (FLIM) to cells. \u0000One of the most important properties of a cell is viscosity, as it affects other parameters, such as the rate of biochemical reactions and particle diffusion. Boron-dipyrromethene (BODIPY) compounds are widely used for viscosity measurements, but current variants have the undesirable sensitivity to polarity, and more suitable alternatives are being sought using theoretical computations. The polarizable continuum model (PCM) used in previous studies did not adequately take into account the influence of the polar environment when calculating the BODIPY activation energy associated with polarity sensitivity. \u0000After applying the multilayer ONIOM method in polar and non-polar environments, the calculated maximum wavelengths of the fluorescence spectra of the 8PhBODIPY compound were closer to the experimental results compared to PCM. The activation energy was also calculated, its value in polar and non-polar environments qualitatively corresponded to the experimental results, and the quantitative agreement was reached using the empirical correction. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140436348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical simulation of proton backscattering spectra in GEANT4 toolkit 在 GEANT4 工具包中对质子反向散射光谱进行数值模拟

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2024-02-23 DOI: 10.3952/physics.2024.64.1.5

D. Lingis, M. Gaspariūnas, V. Kovalevskij, A. Plukis, V. Remeikis

{"title":"Numerical simulation of proton backscattering spectra in GEANT4 toolkit","authors":"D. Lingis, M. Gaspariūnas, V. Kovalevskij, A. Plukis, V. Remeikis","doi":"10.3952/physics.2024.64.1.5","DOIUrl":"https://doi.org/10.3952/physics.2024.64.1.5","url":null,"abstract":"\u0000 \u0000 \u0000Rutherford backscattering spectroscopy (RBS) is a widely used technique for the atomic-scale analysis of sample composition, lattice displacement and impurity profiling. RBS is based on the elastic scattering of incident charged particles by target nuclei and the subsequent detection of scattered particles. The interpretation of RBS spectra, however, poses challenges due to overlapping peaks, corresponding to scattering from different atomic species, and uncertainties from energy loss, scattering geometry and detector response. To address this, an open source simulation model based on the versatile GEANT4 simulation toolkit has been developed. The flexibility of the open source enables users to tailor the model to its specific requirements, such as the use of specific particle stopping powers, cross-sections, and physics processes. This work presents the results of the comparison between the experimental and simulated backscattering spectra in crystalline silicon, silicon carbide and silicon dioxide samples by 1–2.5 MeV energy protons, obtained in random orientation conditions. The results demonstrate the capability of the model to accurately simulate backscattering spectra in both amorphous materials and single crystals. The overall agreement between the simulated and experimental results is highly promising for future development and use in the interpretation and simulation of RBS spectra. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140438002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

THz properties of grating-gate plasmonic crystals crystals 光栅栅极等离子晶体晶体的太赫兹特性

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2023-12-15 DOI: 10.3952/physics.2023.63.4.7

P. Sai, M. Dub, V. Korotyeyev, S. Kukhtaruk, G. Cywiński, W. Knap

{"title":"THz properties of grating-gate plasmonic crystals crystals","authors":"P. Sai, M. Dub, V. Korotyeyev, S. Kukhtaruk, G. Cywiński, W. Knap","doi":"10.3952/physics.2023.63.4.7","DOIUrl":"https://doi.org/10.3952/physics.2023.63.4.7","url":null,"abstract":"\u0000 \u0000 \u0000This study reviews recent advances in the modern field of terahertz plasmonics concerning the control of resonant properties of grating-gate plasmonic crystal structures. Particularly, we conducted both experimental and theoretical investigations of AlGaN/GaN grating-gate structures with a focus on investigations of the resonant structure of transmission spectra associated with plasmon excitations in two-dimensional electron gas at different modulation degree of concentration profiles. Two distinct resonant phases of the plasmonic crystal structure were analyzed. The first one, the delocalized phase, is observed in the case of a small modulation degree of electron gas. In this phase, we found that plasmonic resonant absorption of incident radiation occurs across the entire grating-gate structure, with domination in the gated regions of the electron gas. In contrast, the second phase, the localized one, is realized at a strong modulation of the electron concentration profiles when the gated regions of the electron gas are completely depleted. Here, plasmon resonances are characterized by the spatial localization of absorption of incident radiation exclusively within the ungated regions of the electron gas. Moreover, in the localized phase, we observed the unexpected blue shift of plasmon resonant frequency with an increase of gate voltage. This observation was explained by the result of ‘edge gating effect’ and additional shrinking of the concentration profile of the electron gas in the ungated region. We demonstrate that the correct description of both phases requires rigorous electrodynamic simulations and cannot be achieved solely in the frameworks of simplified single-mode or single-cavity models. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138999527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of parabolic barrier design for multiple GaAsBi/AlGaAs quantum well structures 多砷化镓铋/砷化镓量子阱结构抛物线势垒设计的影响

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2023-12-15 DOI: 10.3952/physics.2023.63.4.8

M. Jokubauskaitė, G. Petrusevičius, A. Špokas, B. Čechavičius, E. Dudutiene, R. Butkutė

{"title":"Effects of parabolic barrier design for multiple GaAsBi/AlGaAs quantum well structures","authors":"M. Jokubauskaitė, G. Petrusevičius, A. Špokas, B. Čechavičius, E. Dudutiene, R. Butkutė","doi":"10.3952/physics.2023.63.4.8","DOIUrl":"https://doi.org/10.3952/physics.2023.63.4.8","url":null,"abstract":"\u0000 \u0000 \u0000The results of a comparative study on how the design of multiple quantum structures containing a parabolic barrier profile affects optical properties are presented. All quantum well (QW) structures were grown by molecular beam epitaxy (MBE) on semi-insulating GaAs substrates. The investigated samples consisted of (i) double parabolic quantum wells (type A) or (ii) multiple (two or three) rectangular quantum wells surrounded by parabolic barriers (type B). The optical quality of samples was characterized performing room-temperature (RT-PL) and temperaturedependent photoluminescence (TD-PL) measurements. The investigation aimed at the optimization of a multiple quantum well (MQW) structure design for application in the gain region of near infrared (NIR) laser diodes (LDs) revealed benefits of both double parabolic quantum wells and a mixed design (rectangular MQW with parabolic barriers). The PL band position for all samples was registered in the vicinity around 1.19 eV, which corresponds to the Bi content in QW of ~4.4%. It was shown that all structures of type A exhibit an intense emission, while the intensity of photoluminescence measured for the samples of type B depends on the number of QWs. The weaker intensity of the PL signal from two QWs inserted between parabolic barriers was explained by a larger point defect density at low temperature grown inner GaAs barriers. The room-temperature PL intensity of the structure with three GaAsBi QWs embedded in one parabolic AlGaAs barrier was the highest one. The shift of PL peak position to lower energies (1.16 eV) was attributed to the slightly higher bismuth concentration, 4.9%. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138998933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Superstrate-lens integration using paraffin wax on top of semiconductor-based THz detector chips 在基于半导体的太赫兹探测器芯片上使用石蜡进行超基底透镜集成

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2023-12-15 DOI: 10.3952/physics.2023.63.4.6

H. Yuan, Q. Ul-Islam, H. Roskos

{"title":"Superstrate-lens integration using paraffin wax on top of semiconductor-based THz detector chips","authors":"H. Yuan, Q. Ul-Islam, H. Roskos","doi":"10.3952/physics.2023.63.4.6","DOIUrl":"https://doi.org/10.3952/physics.2023.63.4.6","url":null,"abstract":"\u0000 \u0000 \u0000A detector of electromagnetic radiation may benefit – if its sensor area is small – from the application of a substrate lens, which focusses the radiation onto the active sensing area of the device and thus enhances its responsivity. The use of such a lens, attached directly onto the detector backside in order to avoid reflection losses, requires that the detector substrate and backside be transparent to the radiation. However, if this is not the case, one may like to place instead a superstrate lens onto the front side of the detector. It may even be of interest to use both a substrate and a superstrate lens if the detector needs to be illuminated with two beams, e.g. for heterodyne detection, where one beam provides the local-oscillator signal. The use of a superstrate lens is, however, often hindered or impeded by an uneven surface topography or by the presence of bonding wires on the front side of the detector. Here, we address this issue and explore the use of paraffin wax to form or attach superstrate lenses. In the first case, which is the main topic of this contribution, we exploit the surface tension of liquid paraffin, brought onto the detector, to sculpt the wax itself into a lens. In the second case, only addressed conceptually here, we use paraffin to form a thin intermediate layer which also acts as an adhesive for the attachment of a plastic or silicon lens. In both cases, the application of liquid paraffin allows one to fill out an uneven detector surface and to embed wires without breaking them. We investigate the use of wax for the case of CMOS TeraFETs – detectors of terahertz radiation based on field-effect transistors – embedded into antenna structures. We describe the processing steps and analyze the performance of a TeraFET equipped with such a wax superstrate lens for front-side beam coupling. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139001022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Study of the low-cost HIPS and paraffin-based terahertz optical components 基于 HIPS 和石蜡的低成本太赫兹光学元件研究

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2023-12-13 DOI: 10.3952/physics.2023.63.4.5

K. Stanaitis, K. Redeckas, A. Bielevičiūtė, M. Bernatonis, D. Jokubauskis, V. Čižas, L. Minkevičius

{"title":"Study of the low-cost HIPS and paraffin-based terahertz optical components","authors":"K. Stanaitis, K. Redeckas, A. Bielevičiūtė, M. Bernatonis, D. Jokubauskis, V. Čižas, L. Minkevičius","doi":"10.3952/physics.2023.63.4.5","DOIUrl":"https://doi.org/10.3952/physics.2023.63.4.5","url":null,"abstract":"\u0000 \u0000 \u0000The ever-increasing popularity of the terahertz (THz) frequency range reveals the increasingly obvious applicability limiting factor – the price of the final setup. This study is intended to contribute to the solution by evaluating the THz frequency range suitability of the optical components, fabricated using two easily accessible materials – high impact polystyrene (HIPS) and paraffin. The primary analysis using time-domain spectroscopy (TDS) revealed promising results, as both materials had sufficient refractive indexes of n ≈ 1.55 and a high transmittance. That allowed one to assume the feasibility of creating a low-cost THz frequency range lens. Lenses of focal lengths of f = 20, 30, 40 mm were fabricated using extrusion 3D printing and paraffin moulding. The produced lenses showcased the satisfactory beam focusing ability, comparable to that of already existing much less cost-efficient solutions. The THz imaging using the fabricated lenses has successfully been realized, proving the applicational possibilities of the imaging system with the proposed low-cost components employed. \u0000 \u0000 \u0000","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139004853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0