Electron-phonon coupling in cuprate and iron-based superconductors revealed by Raman scattering

Electron-phonon coupling （EPC） in cuprate and iron-based superconducting systems, as revealed by Raman scat- tering, is briefly reviewed. We introduce how to extract the coupling information through phonon lineshape. Then we discuss the strength of EPC in different high-temperature superconductor （HTSC） systems and possible factors affecting the strength. A comparative study between Raman phonon theories and experiments allows us to gain insight into some crucial electronic properties, especially superconductivity. Finally, we summarize and compare EPC in the two existing HTSC systems, and discuss what role it may play in the HTSC.

Physically-based modeling for hole scattering rate in strained Si_(1-x) Ge_x/(100)Si

Based on the Fermi's golden rule and the theory of Boltzmann collision term approximation, a physically-based model for hole scattering rate(SR) in strained Si1-x Gex/(100)Si was presented, which takes into account a variety of scattering mechanisms,including ionized impurity, acoustic phonon, non-polar optical phonon and alloy disorder scattering. It is indicated that the SRs of acoustic phonon and non-polar optical phonon decrease under the strain, and the total SR in strained Si1-x Gex/(100)Si also decreases obviously with increasing Ge fraction(x). Moreover, the total SR continues to show a constant tendency when x is less than 0.3. In comparison with bulk Si, the total SR of strained Si1-x Gex/(100) Si decreases by about 58%.

Correlation between mechano-electronic features and scattering rates using deformation potential theory

This research paper provides valuable insight into the electronic,mechanical and transport properties of the Sr_(2)RuO_(2)F_(2)compound.The study shows that the Sr_(2)RuO_(4)compound exhibits a metallic ground state and that the energy gap widens with oxygen substitution with fluorine.The concept of absolute deformation potential and its correlation with band energies and strains is explained using deformation potential theory.The paper also examines the mechanical features of Sr_(2)RuO_(2)F_(2)using the Voigt-Reuss-Hill approximation method and analyzes its elastic constants,bulk modulus and shear modulus,indicating flexibility and suitability for optoelectronic applications.The role of acoustic phonons in scattering rates and carrier mobility in Sr_(2)RuO_(2)F_(2)and its potential for phonon-mediated superconductivity is investigated.The intrinsic resistivity of electrons and holes under strain and its potential impact on superconductivity and electrical resistivity are also discussed.The insight provided by this study contributes to the current understanding of Sr_(2)RuO_(2)F_(2),and its potential applications.

Characteristics and suppression of beam distortion in a high repetition rate nanosecond stimulated Brillouin scattering phase conjugation mirror

The stimulated Brillouin scattering phase conjugation mirror (SBS-PCM) based on liquid media is widely used in high-power laser systems due to its robust thermal load capacity, high energy conversion efficiency and improved beam quality. Nevertheless, with an increase in the pump repetition rate, thermally-induced blooming and optical breakdown can emerge, leading to distortions in the Stokes beam. In this study, we delved into the thermal effects in liquid SBS-PCMs employing hydrodynamic analysis, establishing a relationship between beam profile distortion and the thermal convection field. We calculated the temperature and convection velocity distribution based on the pump light parameters and recorded the corresponding beam profiles. The intensities of the beam profiles were modulated in alignment with the convection directions, reaching a velocity peak of 2.85 mm/s at a pump pulse repetition rate of 250 Hz. The residual sum of squares (RSS) was employed to quantify the extent of beam profile distortion relative to a Gaussian distribution. The RSS escalated to 7.8, in contrast to 0.7 of the pump light at a pump pulse repetition rate of 500 Hz. By suppressing thermal convection using a high-viscosity medium, we effectively mitigated beam distortion. The RSS was reduced to 0.7 at a pump pulse repetition rate of 500 Hz, coinciding with a twentyfold increase in viscosity, thereby enhancing the beam quality. By integrating hydrodynamic analysis, we elucidated and mitigated distortion with targeted solutions. Our research offers an interdisciplinary perspective on studying thermal effects and contributes to the application of SBS-PCMs in high-repetition-rate laser systems by unveiling the mechanism of photothermal effects.

Power-Law Behavior in Signal Scattering Process in Vertical Granular Chain with Light Impurities

We investigate the scattering process of impulse in vertical granular chain with light impurities. When the perturbation is weak, the quantities describing the reflection rate exhibit power-law behavior with the impurity depth. The exponent is nearly independent of vi. When the perturbation is very strong, the vertical chain shows similar behavior to that of the horizontal chain, so the exponent is nearly zero. Our numerical investigation begins from the weak perturbation region and extends to the nonlinear region and found a peak of the exponent. The difficulty in extending the numerical investigation to a stronger perturbation region is analyzed.PACS numbers: 45.70.-n, 43.25.+y, 46.40.

Effect of CC Coherent Vibration on Relative Raman Scattering Cross Sections of All-trans β-Carotene

We have determined the Raman scattering cross sections（RSCSs） of fl-carotene for C=C and C-C stretching modes, with the 1444 cm^-1 Raman band of cyclohexane as internal standard, in different solvents at low concentrations by measuring Raman intensity. The results show that RSCSs of β-carotene were 10^6-10^7 times larger than the general RSCSs, we analyzed that this enhancement was caused not only by the resonance Raman effect but also by nonlinear coherent CC vibration in aqueous β-carotene. Moreover, overtone and combinations of it were also observed and their intensities were 10%-20% of those of their fundamentals when β-carotene was dissolved in non-polar solvents, respectively.

Impact of random and scattered coincidences from outside of field of view on positron emission tomography/computed tomography imaging with different reconstruction protocols

Image quality in positron emission tomography(PET)is affected by random and scattered coincidences and reconstruction protocols.In this study,we investigated the effects of scattered and random coincidences from outside the field of view(FOV)on PET image quality for different reconstruction protocols.Imaging was performed on the Discovery 690 PET/CT scanner,using experimental configurations including the NEMA phantom(a body phantom,with six spheres of different sizes)with a signal background ratio of 4:1.The NEMA phantom(phantom I)was scanned separately in a one-bed position.To simulate the effect of random and scatter coincidences from outside the FOV,six cylindrical phantoms with various diameters were added to the NEMA phantom(phantom II).The 18 emission datasets with mean intervals of 15 min were acquired(3 min/scan).The emission data were reconstructed using different techniques.The image quality parameters were evaluated by both phantoms.Variations in the signal-to-noise ratio(SNR)in a 28-mm(10-mm)sphere of phantom II were 37.9%(86.5%)for ordered-subset expectation maximization(OSEM-only),36.8%(81.5%)for point spread function(PSF),32.7%(80.7%)for time of flight(TOF),and 31.5%(77.8%)for OSEM+PSF+TOF,respectively,indicating that OSEM+PSF+TOF reconstruction had the lowest noise levels and lowest coefficient of variation(COV)values.Random and scatter coincidences from outside the FOV induced lower SNR,lower contrast,and higher COV values,indicating image deterioration and significantly impacting smaller sphere sizes.Amongst reconstruction protocols,OSEM+PSF+TOF and OSEM+PSF showed higher contrast values for sphere sizes of 22,28,and 37 mm and higher contrast recovery coefficient values for smaller sphere sizes of 10 and 13 mm.

内蒙古半干旱区气溶胶散射特性及影响因素

利用2020年7月9日至2023年7月8日锡林浩特市散射系数、黑碳(BC)、PM_(2.5)、PM_(10)、SO_(2)、NO_(2)质量浓度以及气象要素观测资料,从气溶胶散射特性的时间变化、概率密度分布、与不同类型气溶胶和气象因子的相关程度等方面展开分析,并针对该地区开展散射系数等级划分。结果表明:(1)该地区气溶胶散射能力整体水平较低,但是春季沙尘输送、冬季及夜晚逆温出现频率较高会造成该地区气溶胶散射能力的明显增强。(2)粒径越小的气溶胶与散射系数的相关程度越高,与散射系数的相关系数大小依次为BC>PM_(2.5)>PM_(10),但同时具有季节差异性,此外秋、冬季硝酸盐颗粒是造成该地区散射能力增强的重要因素,夏、秋、冬季硫酸盐颗粒对该地区的散射能力也具有一定贡献。(3)以相关系数的增幅作为当前气象因素对散射系数的贡献率,得到当前气象因素对散射系数的贡献率在1%~2%之间。

铜阳极泥选冶联合工艺有价金属走向考察及改进建议

铜阳极泥是资源综合回收的优选对象,分析各有价金属的分散情况对后续的回收有着指导性的方向作用。铜阳极泥选冶联合工艺较为成熟,具有不断外延拓展金属回收的空间。针对4000 t铜阳极泥物料的生产数据,考察了该工艺有价金属的走向,统计分析了金、银、硒、碲、铅、锑、铋、铜等在工艺流程中的分布率,摸清了有价金属主要分散情况。分析表明,金、银、硒、碲最大的分散点均为浮选尾矿,分别占分散总量的67%、37%、34%、58%,确定为重点管控对象。并结合统计分析结果对提高金、银、硒、碲回收率及铅、锑、铋、铜的回收提出了改进建议。

油田用防垢剂的动态防垢评价与多重光散射分析及其应用

采用动态结垢评价法和多重光散射技术分析法研究了3种防垢剂FG-01、FG-02和FG-03的综合防垢效果以及作用机理。动态结垢实验结果表明,FG-03的综合防垢率可达96.24%,效果较好。多重光散射技术分析结果表明:在FG-03作用下,成垢溶液透光率较高,达到85%以上;垢颗粒平均粒径较小,在0.015μm以下,垢颗粒处于分散状态,不易聚集变大,FG-03作用机理以分散作用为主。现场试验效果表明,FG-03可使管道短节内壁干净光滑,防垢效果较好。

基于多重降质复合信道的UWOC系统误码率性能研究

针对海水信道吸收、散射、气泡和湍流效应等对水下无线光通信系统性能的影响,建立融合多重降质效应的水下无线光复合信道模型。基于Mie散射理论计算水下微气泡群的体散射函数、散射系数和散射相函数。湍流信道模型采用混合指数广义伽玛分布进行建模。随后,将复合信道对信号的衰减以及湍流噪声等效传递至光信号,推导出了复合信道在通断键控调制方式下误码率的封闭表达式。此外,研究了湍流强度、气泡数量、链路距离和海水水质等参数对误码率性能的影响。研究结果显示,随着链路距离的延伸,误码率线性增长,表现出退化趋势;港口海水因其较高浊度和丰富的悬浮颗粒,难以保证系统通信的可靠性。此外,气泡的存在和链路距离的扩展同样会显著加剧误码率的恶化。

Semiclassical calculation of ionisation rate for Rydberg helium atoms in an electric field

The ionisation of Rydberg helium atoms in an electric field above the classical ionisation threshold has been examined using the semiclassical method, with particular emphasis on discussing the influence of the core scattering on the escape dynamics of electrons. The results show that the Rydberg helium atoms ionise by emitting a train of electron pulses. Unlike the case of the ionisation of Rydberg hydrogen atom in parallel electric and magnetic fields, where the pulses of the electron are caused by the external magnetic field, the pulse trains for Rydberg helium atoms are created through core scattering. Each peak in the ionisation rate corresponds to the contribution of one core-scattered combination trajectory. This fact further illustrates that the ionic core scattering leads to the chaotic property of the Rydberg helium atom in external fields. Our studies provide a simple explanation for the escape dynamics in the ionisation of nonhydrogenic atoms in external fields.

Two-Fold and Symmetric Repeatability Rates for Comparing Keypoint Detectors

The repeatability rate is an important measure for evaluating and comparing the performance of keypoint detectors.Several repeatability rate measurementswere used in the literature to assess the effectiveness of keypoint detectors.While these repeatability rates are calculated for pairs of images,the general assumption is that the reference image is often known and unchanging compared to other images in the same dataset.So,these rates are asymmetrical as they require calculations in only one direction.In addition,the image domain in which these computations take place substantially affects their values.The presented scatter diagram plots illustrate how these directional repeatability rates vary in relation to the size of the neighboring region in each pair of images.Therefore,both directional repeatability rates for the same image pair must be included when comparing different keypoint detectors.This paper,firstly,examines several commonly utilized repeatability rate measures for keypoint detector evaluations.The researcher then suggests computing a two-fold repeatability rate to assess keypoint detector performance on similar scene images.Next,the symmetric mean repeatability rate metric is computed using the given two-fold repeatability rates.Finally,these measurements are validated using well-known keypoint detectors on different image groups with various geometric and photometric attributes.

Dynamic Deformation Electron-Phonon Interaction in Disordered Bulk Semiconductor

We present our theoretical investigations on the effects of disorder on the electron-phonon interaction in semiconducting GaAs system. Both the temperature (T) and disorder (electron mean free path l) dependences of the electron-phonon scattering rate have been determined. On consideration of the dynamic screening, we find a significant change in the temperature exponent as well as the pre factor from the earlier reported temperature power law dependence result ?T6 obtained under static screening. Also the dynamic screening makes a noticeable change in the character of the dependence of scattering rate on the mean free path from the static screening result.

知母标准汤剂的质量评价方法及指标成分的量值传递规律探索

目的:建立知母标准汤剂的质量评价方法,明确10批知母标准汤剂中指标成分的含量及转移率范围,探索从饮片到标准汤剂,指标成分的量值传递规律。方法:制备10批知母标准汤剂,采用超高效液相色谱-二极管阵列检测器法(UPLC-PDA)对指标成分芒果苷进行含量测定,以0.1%甲酸水(A)-乙腈(B)为流动相进行梯度洗脱(0~3 min,10%~13%B;3~6 min,13%~14%B;6~7 min,14%~90%B),检测波长为258 nm;采用高效液相色谱-蒸发光散射检测器法(HPLC-ELSD)对知母皂苷BⅡ进行含量测定,以乙腈-水(25∶75)为流动相进行等度洗脱,载气流速为2.8 L·min^(–1),漂移管温度为104℃。结果:建立的指标成分含量测定方法的方法学验证均良好,能用于知母标准汤剂中2个指标性成分的定量检测。10批知母标准汤剂中芒果苷、知母皂苷BⅡ的质量分数分别为0.88%~1.12%和0.88%~2.53%,芒果苷含量位于其均值的±30%范围内;转移率分别为45.83%~57.27%和26.94%~43.49%,均在其均值的±30%范围内。结论:建立了知母标准汤剂的质量评价方法,指标成分芒果苷和知母皂苷BⅡ在不同批次的知母饮片与标准汤剂间的转移率一致性较好,表明这2个指标成分在标准汤剂的制备过程中转移情况稳定,为源于知母水煎液的制剂的质量控制方法的制定提供参考。

一种量子级联激光器能带电子温度计算新方法

基于电子动能与温度的关系以及费米黄金定律,对速率方程进行了优化,使其能够计算电子温度,进而实现了更为精准的速率方程求解。与已有的动能平衡法比较,该方法对能带电子温度变化过程进行了详细的描述,故无需采用优化算法求解,所以可以避免因陷入局部最优解而带来的多次计算的收敛值一致性较差的问题。计算结果表明,该方法在选取不同的初始温度时,通过自洽求解,即可解出各能级电子温度,且均可获得一致性较好的收敛值。

直流电场对AP/HTPB/Al复合固体推进剂燃烧特性的影响

为研究直流电场对AP/HTPB/Al复合固体推进剂的燃烧特性的影响,进行了不同电场下的推进剂药条燃烧实验;通过高速可视化拍摄方法,对推进剂药条的燃烧火焰、燃面退移过程及铝凝团运动轨迹进行了观察,分析了不同加载电压对燃烧火焰、燃速及铝凝团散射速度的影响;采用运动学分析方法计算了铝凝团粒子的平均荷质比和受力情况。结果表明:高压电场产生的离子风可以显著改变药条燃烧的火焰形状;药条的燃速随着加载电压的升高而增大,且反向电场对燃速的影响更为显著,最大可提高37%的燃速;铝凝团粒子带正电,平均荷质比约为(1.58±0.04)×10^(-3)C/kg,随着反向电场强度的增加,铝凝团粒子所受的电场力逐步增大,最大可达重力的19倍,散射速度逐步降低,平均散射速度最大可降低49%。

Disassociation of a one-dimensional cold molecule via quantum scattering

Motivated by the recent experimental developments in ultracold molecules and atoms,we propose a simple theoretical model to address the disassociation,reflection,and transmission probability of a one-dimensional cold molecule via quantum scattering.First,we show the Born approximation results in the weak interaction regime.Then,by employing the Lippmann-Schwinger equation,we give the numerical solution and investigate the disassociation’s dependence on the injection momentum and the interaction strengths.We find that the maximum disassociation rate has a limit when increasing the interaction strengths and injection momentum.We expect that our model can be realized in experiments in the near future.

Detection of electron-phonon coupling in two-dimensional materials by light scattering

Electron-phonon coupling affects the properties of two-dimensional(2D)materials significantly,leading to a series of novel phenomena.Inelastic light scattering provides a powerful experimental tool to explore electron-phonon interaction in 2D materials.This review gives an overview of the basic theory and experimental advances of electron-phonon coupling in 2D materials detected by Raman and Brillouin scattering,respectively.In the Raman scattering part,we review Raman spectroscopy studies of electron-phonon coupling in graphene,transition metal disulfide compounds,van der Waals heterostructures,strongly correlated systems,and 2D magnetic materials.In the Brillouin scattering part,we extensively introduce Brillouin spectroscopy in non-van der Waals 2D structures,including temperature sensors for phonons and magnons,interfacial Dzyaloshinsky-Moriya interaction and spin torque in multilayer magnetic structures,as well as exciton-polariton in semiconductor quantum well.

基于佳木斯雷达与北海道东雷达观测的F层不规则体回波发生率

利用佳木斯和北海道东高频相干散射雷达的观测数据,对2018年3月至2019年11月期间两部雷达观测到的F层高度的不规则体回波信号发生率的分布特征进行了对比分析。比较了在地磁平静期(Kp<3)和地磁扰动期(Kp>3)的不规则体回波发生率变化特征,分析了回波发生率在昏侧与晨侧增强的现象和纬度变化特征。昏侧回波发生率增强现象在45°-64°MLAT范围内普遍存在,其中55°-64°MLAT的回波发生率在地磁扰动期明显增强。而晨侧回波发生率增强现象主要分布在45°-54°MLAT的地区,除了春秋分季外,地磁扰动的增强对其影响较弱。中纬日侧回波发生率受地磁活动影响较小。