Moscow University Physics Bulletin最新文献_第4页

A New Microscopic Representation of Spin Dynamics in Quantum Systems with Biquadratic Exchange Interactions 具有双二次交换相互作用的量子系统中自旋动力学的新微观表征

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700255

M. I. Trukhanova, P. Andreev

{"title":"A New Microscopic Representation of Spin Dynamics in Quantum Systems with Biquadratic Exchange Interactions","authors":"M. I. Trukhanova, P. Andreev","doi":"10.3103/S0027134924700255","DOIUrl":"10.3103/S0027134924700255","url":null,"abstract":"There is a version of the Landau–Lifshitz equation that takes into account the Coulomb exchange interactions between atoms, expressed by the term ({sim}mathbf{s}timestrianglemathbf{s}). On the other hand, ions in magnetic materials have several valence electrons on the (d)-shell, and, therefore, the Hamiltonian of many-electron atoms with spins (S>1) should include a biquadratic exchange interaction. We propose a novel fundamental microscopic derivation of the spin density evolution equation with an explicit form of biquadratic exchange interaction using the method of many-particle quantum hydrodynamics. The equation for the spin density evolution is obtained from the many-particle Schrödinger–Pauli equation and contains the contributions of the usual Coulomb exchange interaction and the biquadratic exchange. Furthermore, the derived biquadratic exchange torque in the spin density evolution equation is proportional to the nematic tensor for the medium of atoms with spin (S=1). Our method may be very attractive for further studies of the magnetoelectric effect in multiferroics.","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"232 - 238"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551262","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

Calculation of the Effective Mass of Electrons and Holes of the TlGaTe({}_{mathbf{2}}) Compound 计算碲镓碲 $${}_{mathbf{2}$ 复合物电子和空穴的有效质量

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700346

A. P. Abdullaev, D. M. Gafarova

引用次数: 0

Simulation of the April 27, 2012 Flare Emission in the Spectral Lines of Hydrogen, Helium, and Calcium 模拟 2012 年 4 月 27 日耀斑的氢、氦和钙光谱线发射

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700334

Yu. A. Kupryakov, K. V. Bychkov, O. M. Belova, V. A. Maliutin, A. B. Gorshkov

{"title":"Simulation of the April 27, 2012 Flare Emission in the Spectral Lines of Hydrogen, Helium, and Calcium","authors":"Yu. A. Kupryakov, K. V. Bychkov, O. M. Belova, V. A. Maliutin, A. B. Gorshkov","doi":"10.3103/S0027134924700334","DOIUrl":"10.3103/S0027134924700334","url":null,"abstract":"The paper presents the results of the analysis of the sloar flare SOL2012-04-27 emission in hydrogen, helium, and calcium spectral lines observed on the horizontal solar facility HSFA-2 of the Ondřejov Observatory (Astronomical Institute of the Czech Academy of Sciences). After processing the spectra, the integrated emission fluxes in the lines were determined. The data collected are treated using the approach of rapid energy release inside the chromosphere, accompanied by gas evaporation. Within the framework of the heated gas model, a theoretical calculation of the plasma parameters was performed, taking into account the physical conditions in the chromosphere, including spectral line self-absorption. Comparison across six lines allowed, with a high degree of validity, the reconstruction of the temperature (T), density, and spatial structure of the emitting gas. The best agreement of theory with observations is obtained in the model of the spread of inhomogeneous clouds, each of which has hot ((Tapprox 18,000{-}19,500) K) and less heated ((Tapprox 8000{-}9000) K) regions. On average, one cloud contributes about ten percent to the total emission flux.","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"275 - 282"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551247","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

Laser–Electron Source of X-Ray Radiation (Based on the Introductory Speech at the Seminar Dedicated to the 85th Anniversary of B.S. Ishkhanov in SINP MSU, October 26, 2023) X 射线激光电子源（根据 2023 年 10 月 26 日在莫斯科国立自治大学 SINP 纪念 B.S.伊什哈诺夫诞辰 85 周年研讨会上的发言整理）

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700188

I. A. Artyukov, A. V. Vinogradov, V. I. Shevdunov

{"title":"Laser–Electron Source of X-Ray Radiation (Based on the Introductory Speech at the Seminar Dedicated to the 85th Anniversary of B.S. Ishkhanov in SINP MSU, October 26, 2023)","authors":"I. A. Artyukov, A. V. Vinogradov, V. I. Shevdunov","doi":"10.3103/S0027134924700188","DOIUrl":"10.3103/S0027134924700188","url":null,"abstract":"The paper, like the seminar where it was presented, is dedicated to the memory of the outstanding physicist and nuclear scientist, Professor of Moscow State University B.S. Ishkhanov, more precisely, to his contribution to the research and development of LEXG—laser–electron X-ray generators. The relevance and prospects of this direction are associated with the ‘‘gap’’ between two existing types of X-ray generators: on the one hand, X-ray tubes, and on the other, electron accelerators, storage rings, and free electron lasers. This involves a vast difference in beam characteristics, cost, scale, energy consumption, etc. The history of LEXG, modern projects abroad, as well as the Lomonosov Moscow State University–Jilin University project, carried out under the supervision of B.S. Ishkhanov, are briefly presented. From the point of view of their applications, LEXG designs can be divided into two types and, accordingly, devices of different scales. In the first case, it is the application area of common X-ray tubes, and in the second, it is radiation medicine, nuclear technologies, and nuclear physics research. International conferences on LEXG have been held since 2008. Their list is provided in the Appendix to the article.","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"208 - 213"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551259","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

Phase Transition Face-Centered Cubic Crystal—Homogeneous Phase in Helium 氦气中的面心立方晶体-均相转变

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700267

P. N. Nikolaev

引用次数: 0

Assessment of Dynamic Disorder in DNA Oligonucleotides Using Low-Frequency Raman Spectroscopy 利用低频拉曼光谱评估 DNA 寡核苷酸中的动态乱序

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S002713492470019X

A. Yu. Sosorev, O. D. Paraschuk, A. A. Trubitsyn, N. O. Dubinets, I. V. Chicherin, D. Yu. Paraschuk

{"title":"Assessment of Dynamic Disorder in DNA Oligonucleotides Using Low-Frequency Raman Spectroscopy","authors":"A. Yu. Sosorev, O. D. Paraschuk, A. A. Trubitsyn, N. O. Dubinets, I. V. Chicherin, D. Yu. Paraschuk","doi":"10.3103/S002713492470019X","DOIUrl":"10.3103/S002713492470019X","url":null,"abstract":"The degree of DNA compaction in various regions of the cell nucleus determines whether the corresponding genes should be expressed and other crucial cellular processes, such as DNA replication and repair, should occur. Therefore, the development of approaches to the experimental assessment of DNA compactness in cell nuclei, as well as its indicator, dynamic disorder which determines the degree of thermal fluctuation in the position and mutual orientation of molecular fragments, is highly relevant. In this paper, using single-stranded guanine and cytosine oligonucleotides, as well as their double-stranded combination as an example, it is shown that dynamic disorder in DNA can be assessed based on low-frequency Raman scattering (RS) spectroscopy data. For the first time, Raman spectra of oligonucleotides have been measured over a wide frequency range, including the low-frequency (10–200 cm({}^{-1})) and high-frequency (200–2000 cm({}^{-1})) regions. It was found that the low-frequency Raman intensity is maximal in single-stranded oligocytosine and minimal in the double-stranded oligonucleotide, which is in full agreement with the magnitude of dynamic disorder estimated from molecular dynamics simulations. The obtained results indicate the promising application of low-frequency Raman spectroscopy for assessing dynamic disorder and DNA compactness. The use of such a technique is expected to contribute to the understanding of key cellular processes and the physical mechanisms that underlie them, which is necessary for the development of advanced methods in molecular biophysics and cell biology.","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"248 - 258"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551202","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

Photonuclear Experiments: From Bremsstrahlung to Backward Compton Scattering Photons 光核实验：从轫致辐射到后向康普顿散射光子

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S002713492470022X

V. V. Varlamov, A. I. Davydov

引用次数: 0

Storage Ring of the Compton Source of the NCPM 国家清洁生产中心康普顿源存储环

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S002713492470036X

D. A. Bobylev, V. I. Shvedunov

引用次数: 0

Field Electron Emission from Point Diamond Cathodes under Continuous Laser Irradiation 连续激光照射下点金刚石阴极的场电子发射

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700292

V. I. Kleshch, I. R. Anderzhanov, R. R. Ismagilov, A. N. Obraztsov

{"title":"Field Electron Emission from Point Diamond Cathodes under Continuous Laser Irradiation","authors":"V. I. Kleshch, I. R. Anderzhanov, R. R. Ismagilov, A. N. Obraztsov","doi":"10.3103/S0027134924700292","DOIUrl":"10.3103/S0027134924700292","url":null,"abstract":"The results of the study on the impact of continuous visible laser irradiation on the field emission properties of point cathodes which are diamond needle-like microsized crystallites with a nanometer tip radius, are presented. The measurements were conducted in a vacuum diode configuration with a flat metal anode using DC voltage source. An increase in the field emission current was observed when the diamond needle was illuminated by laser radiation. The magnitude of the current changes directly proportional to the power of the radiation. At a maximum power density value of about 400 W/cm({}^{2}), the relative increase in current under the action of laser irradiation was 13(%). The relative increase in current is determined by the parameters of the dark current–voltage characteristic and reaches its maximum value in the region corresponding to the minimal increase in dark current with voltage. It is shown that the most probable mechanism for the current increase is the change in the electrical resistance of the diamond microneedle as a result of the absorption of laser radiation with the involvement of electronic levels located in the bandgap of diamond, associated with impurities or structural defects in the near surface layer of the diamond microneedle.","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"259 - 263"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551203","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

Beam Scanning System of an Industrial Electron Accelerator 工业电子加速器的光束扫描系统

IF 0.4 4区物理与天体物理

Moscow University Physics Bulletin Pub Date : 2024-07-04 DOI: 10.3103/S0027134924700231

M. A. Borisov, V. I. Shvedunov

引用次数: 0