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Phase field crystal models with applications to laser deposition: A review. 应用于激光沉积的相场晶体模型:综述。
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2024-01-31 eCollection Date: 2024-01-01 DOI: 10.1063/4.0000226
Duncan Burns, Nikolas Provatas, Martin Grant

In this article, we address the application of phase field crystal (PFC) theory, a hybrid atomistic-continuum approach, for modeling nanostructure kinetics encountered in laser deposition. We first provide an overview of the PFC methodology, highlighting recent advances to incorporate phononic and heat transport mechanisms. To simulate laser heating, energy is deposited onto a number of polycrystalline, two-dimensional samples through the application of initial stochastic fluctuations. We first demonstrate the ability of the model to simulate plasticity and recrystallization events that follow laser heating in the isothermal limit. Importantly, we also show that sufficient kinetic energy can cause voiding, which serves to suppress shock propagation. We subsequently employ a newly developed thermo-density PFC theory, coined thermal field crystal (TFC), to investigate laser heating of polycrystalline samples under non-isothermal conditions. We observe that the latent heat of transition associated with ordering can lead to long lasting metastable structures and defects, with a healing rate linked to the thermal diffusion. Finally, we illustrate that the lattice temperature simulated by the TFC model is in qualitative agreement with predictions of conventional electron-phonon two-temperature models. We expect that our new TFC formalism can be useful for predicting transient structures that result from rapid laser heating and re-solidification processes.

在本文中,我们探讨了相场晶体 (PFC) 理论的应用,这是一种原子-连续混合方法,用于对激光沉积过程中遇到的纳米结构动力学进行建模。我们首先概述了 PFC 方法,重点介绍了将声子和热传输机制纳入其中的最新进展。为了模拟激光加热,通过应用初始随机波动将能量沉积到一些多晶二维样品上。我们首先展示了该模型模拟等温极限激光加热后塑性和再结晶事件的能力。重要的是,我们还证明了足够的动能可导致空化,从而抑制冲击波的传播。随后,我们采用新开发的热密度 PFC 理论(被称为热场晶体 (TFC))来研究非等温条件下多晶样品的激光加热。我们观察到,与有序化相关的转变潜热可导致持久的陨变结构和缺陷,其愈合率与热扩散相关。最后,我们说明了 TFC 模型模拟的晶格温度与传统电子-声子双温模型的预测结果在本质上是一致的。我们希望我们新的 TFC 形式主义能在预测快速激光加热和再凝固过程产生的瞬态结构方面发挥作用。
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引用次数: 0
Relativistic ultrafast electron diffraction at high repetition rates. 高重复率的相对论超快电子衍射。
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2023-12-04 eCollection Date: 2023-11-01 DOI: 10.1063/4.0000203
K M Siddiqui, D B Durham, F Cropp, F Ji, S Paiagua, C Ophus, N C Andresen, L Jin, J Wu, S Wang, X Zhang, W You, M Murnane, M Centurion, X Wang, D S Slaughter, R A Kaindl, P Musumeci, A M Minor, D Filippetto

The ability to resolve the dynamics of matter on its native temporal and spatial scales constitutes a key challenge and convergent theme across chemistry, biology, and materials science. The last couple of decades have witnessed ultrafast electron diffraction (UED) emerge as one of the forefront techniques with the sensitivity to resolve atomic motions. Increasingly sophisticated UED instruments are being developed that are aimed at increasing the beam brightness in order to observe structural signatures, but so far they have been limited to low average current beams. Here, we present the technical design and capabilities of the HiRES (High Repetition-rate Electron Scattering) instrument, which blends relativistic electrons and high repetition rates to achieve orders of magnitude improvement in average beam current compared to the existing state-of-the-art instruments. The setup utilizes a novel electron source to deliver femtosecond duration electron pulses at up to MHz repetition rates for UED experiments. Instrument response function of sub-500 fs is demonstrated with < 100 fs time resolution targeted in future. We provide example cases of diffraction measurements on solid-state and gas-phase samples, including both micro- and nanodiffraction (featuring 100 nm beam size) modes, which showcase the potential of the instrument for novel UED experiments.

在其固有的时间和空间尺度上解决物质动力学的能力构成了化学、生物学和材料科学的关键挑战和融合主题。在过去的几十年里,超快电子衍射(UED)作为一种灵敏的原子运动解析技术出现了。越来越复杂的UED仪器正在开发,旨在提高光束亮度,以观察结构特征,但到目前为止,它们仅限于低平均电流光束。在这里,我们介绍了雇用(高重复率电子散射)仪器的技术设计和能力,它混合了相对论电子和高重复率,与现有的最先进的仪器相比,平均光束电流提高了几个数量级。该装置利用一种新型电子源,为UED实验提供高达MHz重复率的飞秒持续电子脉冲。演示了仪器在低于500fs的响应功能,并以未来< 100fs的时间分辨率为目标。我们提供了固体和气相样品的衍射测量实例,包括微衍射和纳米衍射(具有100 nm光束尺寸)模式,这展示了该仪器在新型UED实验中的潜力。
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引用次数: 1
Photodiode-based time zero determination for ultrafast electron microscopy. 用于超快电子显微镜的基于光电二极管的时间零点测定。
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2023-11-06 eCollection Date: 2023-11-01 DOI: 10.1063/4.0000218
S T Kempers, S Borrelli, E R Kieft, H A van Doorn, P H A Mutsaers, O J Luiten

Pump-probe experiments in ultrafast electron microscopy require temporal overlap between the pump and probe pulses. Accurate measurements of the time delay between them allows for the determination of the time zero, the moment in time where both pulses perfectly overlap. In this work, we present the use of a photodiode-based alignment method for these time zero measurements. The cheap and easy-to-use device consists of a photodiode in a sample holder and enables us to temporally align individual, single-electron pulses with femtosecond laser pulses. In a first device, a temporal resolution of 24 ps is obtained, limited by the photodiode design. Future work will utilize a smaller photodiode with a lower capacitance, which will increase the temporal resolution and add spatial resolution as well. This upgrade will bring the method toward the micrometer and picosecond spatiotemporal resolution.

超快电子显微镜中的泵浦-探针实验需要泵浦脉冲和探针脉冲之间的时间重叠。精确测量它们之间的时间延迟可以确定时间零点,即两个脉冲完全重叠的时刻。在这项工作中,我们提出了使用基于光电二极管的对准方法进行这些时间零点测量。这种廉价易用的设备由样品支架中的光电二极管组成,使我们能够在时间上将单个单电子脉冲与飞秒激光脉冲对准。在第一器件中,由于光电二极管设计的限制,获得了24ps的时间分辨率。未来的工作将使用电容较低的较小光电二极管,这将提高时间分辨率并增加空间分辨率。这一升级将使该方法达到微米和皮秒的时空分辨率。
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引用次数: 0
A Δ-learning strategy for interpretation of spectroscopic observables. 用于解释光谱可观察性的Δ-学习策略。
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2023-11-06 eCollection Date: 2023-11-01 DOI: 10.1063/4.0000215
Luke Watson, Thomas Pope, Raphael M Jay, Ambar Banerjee, Philippe Wernet, Thomas J Penfold

Accurate computations of experimental observables are essential for interpreting the high information content held within x-ray spectra. However, for complicated systems this can be difficult, a challenge compounded when dynamics becomes important owing to the large number of calculations required to capture the time-evolving observable. While machine learning architectures have been shown to represent a promising approach for rapidly predicting spectral lineshapes, achieving simultaneously accurate and sufficiently comprehensive training data is challenging. Herein, we introduce Δ-learning for x-ray spectroscopy. Instead of directly learning the structure-spectrum relationship, the Δ-model learns the structure dependent difference between a higher and lower level of theory. Consequently, once developed these models can be used to translate spectral shapes obtained from lower levels of theory to mimic those corresponding to higher levels of theory. Ultimately, this achieves accurate simulations with a much reduced computational burden as only the lower level of theory is computed, while the model can instantaneously transform this to a spectrum equivalent to a higher level of theory. Our present model, demonstrated herein, learns the difference between TDDFT(BLYP) and TDDFT(B3LYP) spectra. Its effectiveness is illustrated using simulations of Rh L3-edge spectra tracking the C-H activation of octane by a cyclopentadienyl rhodium carbonyl complex.

实验可观测值的精确计算对于解释x射线光谱中的高信息含量至关重要。然而,对于复杂的系统来说,这可能很困难,当动力学变得重要时,由于需要大量的计算来捕捉时间演变的可观测值,这一挑战变得更加复杂。虽然机器学习架构已被证明是快速预测谱线形状的一种很有前途的方法,但同时获得准确和足够全面的训练数据是一项挑战。在这里,我们介绍了x射线光谱的Δ学习。Δ-模型不是直接学习结构-谱关系,而是学习较高和较低理论水平之间的结构相关差异。因此,一旦开发出这些模型,就可以用来转换从较低理论水平获得的光谱形状,以模拟与较高理论水平相对应的光谱形状。最终,这实现了精确的模拟,大大减少了计算负担,因为只计算较低水平的理论,而模型可以立即将其转换为相当于较高水平理论的频谱。我们目前的模型,在此演示,学习TDDFT(BLYP)和TDDFT(B3LYP)光谱之间的差异。通过模拟Rh L3边缘光谱跟踪环戊二烯基铑羰基络合物对辛烷的C-H活化,说明了其有效性。
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引用次数: 0
Disentangling the evolution of electrons and holes in photoexcited ZnO nanoparticles. 解开光激发ZnO纳米颗粒中电子和空穴的演化。
IF 2.3 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2023-11-03 eCollection Date: 2023-11-01 DOI: 10.1063/4.0000204
Christopher J Milne, Natalia Nagornova, Thomas Pope, Hui-Yuan Chen, Thomas Rossi, Jakub Szlachetko, Wojciech Gawelda, Alexander Britz, Tim B van Driel, Leonardo Sala, Simon Ebner, Tetsuo Katayama, Stephen H Southworth, Gilles Doumy, Anne Marie March, C Stefan Lehmann, Melanie Mucke, Denys Iablonskyi, Yoshiaki Kumagai, Gregor Knopp, Koji Motomura, Tadashi Togashi, Shigeki Owada, Makina Yabashi, Martin M Nielsen, Marek Pajek, Kiyoshi Ueda, Rafael Abela, Thomas J Penfold, Majed Chergui

The evolution of charge carriers in photoexcited room temperature ZnO nanoparticles in solution is investigated using ultrafast ultraviolet photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy, and ab initio molecular dynamics (MD) simulations. The photoluminescence is excited at 4.66 eV, well above the band edge, and shows that electron cooling in the conduction band and exciton formation occur in <500 fs, in excellent agreement with theoretical predictions. The x-ray absorption measurements, obtained upon excitation close to the band edge at 3.49 eV, are sensitive to the migration and trapping of holes. They reveal that the 2 ps transient largely reproduces the previously reported transient obtained at 100 ps time delay in synchrotron studies. In addition, the x-ray absorption signal is found to rise in ∼1.4 ps, which we attribute to the diffusion of holes through the lattice prior to their trapping at singly charged oxygen vacancies. Indeed, the MD simulations show that impulsive trapping of holes induces an ultrafast expansion of the cage of Zn atoms in <200 fs, followed by an oscillatory response at a frequency of ∼100 cm-1, which corresponds to a phonon mode of the system involving the Zn sub-lattice.

利用超快紫外光致发光光谱、超快Zn K边吸收光谱和从头算分子动力学(MD)模拟研究了溶液中光激发室温ZnO纳米颗粒中电荷载流子的演化。光致发光在4.66激发 eV,远高于带边缘,并表明导带中的电子冷却和激子形成发生在-1中,这对应于涉及Zn亚晶格的系统的声子模式。
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引用次数: 0
Non-thermal structural transformation of diamond driven by x-rays. x射线驱动下金刚石的非热结构转变。
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2023-10-27 eCollection Date: 2023-09-01 DOI: 10.1063/4.0000193
Philip Heimann, Nicholas J Hartley, Ichiro Inoue, Victor Tkachenko, Andre Antoine, Fabien Dorchies, Roger Falcone, Jérôme Gaudin, Hauke Höppner, Yuichi Inubushi, Konrad J Kapcia, Hae Ja Lee, Vladimir Lipp, Paloma Martinez, Nikita Medvedev, Franz Tavella, Sven Toleikis, Makina Yabashi, Toshinori Yabuuchi, Jumpei Yamada, Beata Ziaja

Intense x-ray pulses can cause the non-thermal structural transformation of diamond. At the SACLA XFEL facility, pump x-ray pulses triggered this phase transition, and probe x-ray pulses produced diffraction patterns. Time delays were observed from 0 to 250 fs, and the x-ray dose varied from 0.9 to 8.0 eV/atom. The intensity of the (111), (220), and (311) diffraction peaks decreased with time, indicating a disordering of the crystal lattice. From a Debye-Waller analysis, the rms atomic displacements perpendicular to the (111) planes were observed to be significantly larger than those perpendicular to the (220) or (311) planes. At a long time delay of 33 ms, graphite (002) diffraction indicates that graphitization did occur above a threshold dose of 1.2 eV/atom. These experimental results are in qualitative agreement with XTANT+ simulations using a hybrid model based on density-functional tight-binding molecular dynamics.

强x射线脉冲可以引起金刚石的非热结构转变。在SACLA XFEL设施中,泵浦x射线脉冲触发了这种相变,探针x射线脉冲产生衍射图案。从0到250 fs观察到时间延迟,x射线剂量从0.9到8.0不等 eV/原子。(111)、(220)和(311)衍射峰的强度随着时间的推移而降低,表明晶格无序。根据Debye Waller分析,观察到垂直于(111)平面的均方根原子位移显著大于垂直于(220)或(311)平面的原子位移。在33的长时间延迟 ms,石墨(002)衍射表明石墨化确实发生在1.2的阈值剂量以上 eV/原子。这些实验结果与使用基于密度泛函紧密结合分子动力学的混合模型的XTANT+模拟在质量上一致。
{"title":"Non-thermal structural transformation of diamond driven by x-rays.","authors":"Philip Heimann,&nbsp;Nicholas J Hartley,&nbsp;Ichiro Inoue,&nbsp;Victor Tkachenko,&nbsp;Andre Antoine,&nbsp;Fabien Dorchies,&nbsp;Roger Falcone,&nbsp;Jérôme Gaudin,&nbsp;Hauke Höppner,&nbsp;Yuichi Inubushi,&nbsp;Konrad J Kapcia,&nbsp;Hae Ja Lee,&nbsp;Vladimir Lipp,&nbsp;Paloma Martinez,&nbsp;Nikita Medvedev,&nbsp;Franz Tavella,&nbsp;Sven Toleikis,&nbsp;Makina Yabashi,&nbsp;Toshinori Yabuuchi,&nbsp;Jumpei Yamada,&nbsp;Beata Ziaja","doi":"10.1063/4.0000193","DOIUrl":"https://doi.org/10.1063/4.0000193","url":null,"abstract":"<p><p>Intense x-ray pulses can cause the non-thermal structural transformation of diamond. At the SACLA XFEL facility, pump x-ray pulses triggered this phase transition, and probe x-ray pulses produced diffraction patterns. Time delays were observed from 0 to 250 fs, and the x-ray dose varied from 0.9 to 8.0 eV/atom. The intensity of the (111), (220), and (311) diffraction peaks decreased with time, indicating a disordering of the crystal lattice. From a Debye-Waller analysis, the rms atomic displacements perpendicular to the (111) planes were observed to be significantly larger than those perpendicular to the (220) or (311) planes. At a long time delay of 33 ms, graphite (002) diffraction indicates that graphitization did occur above a threshold dose of 1.2 eV/atom. These experimental results are in qualitative agreement with XTANT+ simulations using a hybrid model based on density-functional tight-binding molecular dynamics.</p>","PeriodicalId":48683,"journal":{"name":"Structural Dynamics-Us","volume":"10 5","pages":"054502"},"PeriodicalIF":2.8,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10613085/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71414817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Solution phase high repetition rate laser pump x-ray probe picosecond hard x-ray spectroscopy at the Stanford Synchrotron Radiation Lightsource. 斯坦福同步辐射光源的溶液相高重复率激光泵浦x射线探针皮秒硬x射线光谱。
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2023-10-27 eCollection Date: 2023-09-01 DOI: 10.1063/4.0000207
Marco Reinhard, Dean Skoien, Jacob A Spies, Angel T Garcia-Esparza, Benjamin D Matson, Jeff Corbett, Kai Tian, James Safranek, Eduardo Granados, Matthew Strader, Kelly J Gaffney, Roberto Alonso-Mori, Thomas Kroll, Dimosthenis Sokaras

We present a dedicated end-station for solution phase high repetition rate (MHz) picosecond hard x-ray spectroscopy at beamline 15-2 of the Stanford Synchrotron Radiation Lightsource. A high-power ultrafast ytterbium-doped fiber laser is used to photoexcite the samples at a repetition rate of 640 kHz, while the data acquisition operates at the 1.28 MHz repetition rate of the storage ring recording data in an alternating on-off mode. The time-resolved x-ray measurements are enabled via gating the x-ray detectors with the 20 mA/70 ps camshaft bunch of SPEAR3, a mode available during the routine operations of the Stanford Synchrotron Radiation Lightsource. As a benchmark study, aiming to demonstrate the advantageous capabilities of this end-station, we have conducted picosecond Fe K-edge x-ray absorption spectroscopy on aqueous [FeII(phen)3]2+, a prototypical spin crossover complex that undergoes light-induced excited spin state trapping forming an electronic excited state with a 0.6-0.7 ns lifetime. In addition, we report transient Fe Kβ main line and valence-to-core x-ray emission spectra, showing a unique detection sensitivity and an excellent agreement with model spectra and density functional theory calculations, respectively. Notably, the achieved signal-to-noise ratio, the overall performance, and the routine availability of the developed end-station have enabled a systematic time-resolved science program using the monochromatic beam at the Stanford Synchrotron Radiation Lightsource.

我们在斯坦福同步辐射光源的光束线15-2上提出了一个用于溶液相高重复率(MHz)皮秒硬x射线光谱的专用终端站。用高功率超快掺镱光纤激光器以640的重复频率对样品进行了光激发 kHz,而数据采集工作在1.28 以交替开关模式记录数据的存储环的MHz重复率。时间分辨x射线测量是通过20 SPEAR3的mA/70ps凸轮轴束,这是斯坦福同步加速器辐射光源常规操作期间可用的模式。作为一项基准研究,旨在证明该终端站的优势能力,我们在水性[FeII(phen)3]2+上进行了皮秒Fe K边x射线吸收光谱,这是一种典型的自旋交叉复合物,经过光诱导的激发自旋态捕获,形成0.6-0.7的电子激发态 ns寿命。此外,我们报道了瞬态Fe Kβ主线和价核x射线发射光谱,分别显示出独特的探测灵敏度和与模型光谱和密度泛函理论计算的良好一致性。值得注意的是,所实现的信噪比、整体性能和所开发的终端站的常规可用性使斯坦福同步辐射光源能够使用单色光束进行系统的时间分辨科学计划。
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引用次数: 0
Tailored nanophononic wavefield in a patterned bilayer system probed by ultrafast convergent beam electron diffraction 用超快会聚束电子衍射探测双层系统中的定制纳米声子波场
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2022-05-01 DOI: 10.1063/4.0000144
N. Bach, A. Feist, M. Möller, C. Ropers, S. Schäfer
Optically excited nanostructures provide a versatile platform for the generation of confined nanophononic fields with potential (non-)linear interactions between different degrees of freedom. Control of resonance frequencies and the selective excitation of acoustic modes still remains challenging due to the interplay of nanoscale geometries and interfacial coupling mechanisms. Here, we demonstrate that a semiconductor membrane patterned with a platinum stripe acts as a tailored source for high-frequency strain waves generating a multi-modal distortion wave propagating through the membrane. To locally monitor the ultrafast structural dynamics at a specific distance from the deposited metal stripe, we employ ultrafast convergent beam electron diffraction in a laser-pump/electron-probe scheme. Experimentally observed acoustic deformations are reproduced by numerical simulations in a continuous medium model, revealing a spatiotemporal evolution of the lattice dynamics dominated by local rotations with minor strain and shear contributions.
光激发纳米结构为产生具有不同自由度之间的潜在(非线性)相互作用的受限纳米声子场提供了一个通用平台。由于纳米级几何结构和界面耦合机制的相互作用,共振频率的控制和声模式的选择性激发仍然具有挑战性。在这里,我们证明了具有铂条纹图案的半导体膜作为高频应变波的定制源,产生通过膜传播的多模态畸变波。为了在与沉积金属条一定距离处局部监测超快结构动力学,我们采用激光泵浦/电子探针方案中的超快会聚束电子衍射。在连续介质模型中,通过数值模拟再现了实验观察到的声学变形,揭示了晶格动力学的时空演化,该演化由局部旋转主导,应变和剪切贡献较小。
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引用次数: 1
Temperature measurements of liquid flat jets in vacuum 真空中液体平面射流的温度测量
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2021-12-10 DOI: 10.1063/4.0000139
Yi-Ping Chang, Z. Yin, T. Balciunas, H. Wörner, J. Wolf
Sub-μm thin samples are essential for spectroscopic purposes. The development of flat micro-jets enabled novel spectroscopic and scattering methods for investigating molecular systems in the liquid phase. However, the temperature of these ultra-thin liquid sheets in vacuum has not been systematically investigated. Here, we present a comprehensive temperature characterization using optical Raman spectroscopy of sub-micron flatjets produced by two different methods: colliding of two cylindrical jets and a cylindrical jet compressed by a high pressure gas. Our results reveal the dependence of the cooling rate on the material properties and the source characteristics, i.e., nozzle-orifice size, flow rate, and pressure. We show that materials with higher vapor pressures exhibit faster cooling rates, which is illustrated by comparing the temperature profiles of water and ethanol flatjets. In a sub-μm liquid sheet, the temperature of the water sample reaches around 268 K and the ethanol around 253 K close to the flatjet's terminus.
亚μm薄的样品对于光谱学的目的是必不可少的。扁平微射流的发展为研究液相分子系统提供了新的光谱和散射方法。然而,这些超薄液体片在真空中的温度还没有系统的研究。在这里,我们利用光学拉曼光谱对两种不同方法产生的亚微米平面射流进行了全面的温度表征:两个圆柱形射流碰撞和一个圆柱形射流被高压气体压缩。我们的研究结果揭示了冷却速率与材料性能和源特性(即喷嘴孔尺寸、流量和压力)的关系。通过比较水和乙醇平板射流的温度分布,我们发现具有较高蒸汽压的材料表现出更快的冷却速度。在亚μm液片中,水样温度达到268 K左右,乙醇温度达到253 K左右。
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引用次数: 7
Free Vibration of Single Degree of Freedom System 单自由度系统的自由振动
IF 2.8 2区 物理与天体物理 Q3 CHEMISTRY, PHYSICAL Pub Date : 2021-01-01 DOI: 10.1007/978-3-030-69674-0_2
M. Mukhopadhyay
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引用次数: 0
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