作者:冯维维 来源:科学网微信公众号 发布时间:2024/6/23 20:37:23



Nature, 20 June 2024, Volume 630 Issue 8017

《自然》, 2024年6月20日,第630卷,8017期



A secondary atmosphere on the rocky exoplanet 55 Cancri e


▲ 作者:Renyu Hu, Aaron Bello-Arufe, Michael Zhang, Kimberly Paragas, Mantas Zilinskas, Christiaan van Buchem, Michael Bess, Jayshil Patel, Yuichi Ito, Mario Damiano, Markus Scheucher, Apurva V. Oza, Heather A. Knutson, Yamila Miguel, Diana Dragomir, Alexis Brandeker & Brice-Olivier Demory

▲ 链接:


▲ 摘要:

描绘岩石系外行星的特征是天文学的中心目标,然而迄今为止,在岩石系外行星上寻找大气的结果要么是大气质量的严格上限,要么是不确定的结果。相当于1.95个地球半径和8.8个地球质量的行星——巨蟹座55 e(以下简称55Cnc e),主要由岩石组成,平衡温度约为2000 K,可能有一个挥发性的包层(包含由C、H、O、N、S和P元素组合而成的分子),占其半径的百分之几。

研究者利用透射光谱对该行星进行了广泛的观测,并在宽光度波段测量了其热辐射。这些观测不支持原始H2/ he主导的大气,但不能最终确定该行星是否有次级大气。

研究者报道了由詹姆斯韦布太空望远镜获得的行星4 ~ 12μm的热发射光谱。测量结果排除了这颗行星是一个熔岩世界,被由蒸发岩石组成的稀薄大气所覆盖的可能性,表明它是一个真正的挥发性大气,可能富含二氧化碳或一氧化碳。这种大气可以从岩浆海洋中释放出来,并由岩浆海洋维持。

▲ Abstract:

Characterizing rocky exoplanets is a central aim of astronomy, and yet the search for atmospheres on rocky exoplanets has so far resulted in either tight upper limits on the atmospheric mass or inconclusive results. The 1.95REarth and 8.8MEarth planet 55?Cancri?e (abbreviated 55?Cnc?e), with a predominantly rocky composition and an equilibrium temperature of around 2,000?K, may have a volatile envelope (containing molecules made from a combination of C, H, O, N, S and P elements) that accounts for up to a few percent of its radius. The planet has been observed extensively with transmission spectroscopy and its thermal emission has been measured in broad photometric bands. These observations disfavour a primordial H2/He-dominated atmosphere but cannot conclusively determine whether the planet has a secondary atmosphere. Here we report a thermal emission spectrum of the planet obtained by the NIRCam and MIRI instruments aboard the James Webb Space Telescope (JWST) from 4 to 12?μm. The measurements rule out the scenario in which the planet is a lava world shrouded by a tenuous atmosphere made of vaporized rock and indicate a bona fide volatile atmosphere that is probably rich in CO2 or CO. This atmosphere can be outgassed from and sustained by a magma ocean.

A site-resolved two-dimensional quantum simulator with hundreds of trapped ions


▲ 作者:S.-A. Guo, Y.-K. Wu, J. Ye, L. Zhang, W.-Q. Lian, R. Yao, Y. Wang, R.-Y. Yan, Y.-J. Yi, Y.-L. Xu, B.-W. Li, Y.-H. Hou, Y.-Z. Xu, W.-X. Guo, C. Zhang, B.-X. Qi, Z.-C. Zhou, L. He & L.-M. Duan

▲ 链接:


▲ 摘要:

大量子位容量和单个读出能力是大规模量子计算和模拟的两个关键要求。作为量子信息处理的主要物理平台之一,离子阱已经在一维保罗阱中实现了数十个具有位置分辨读出的离子的量子模拟,在二维 Penning阱中实现了数百个具有全局可观测值的离子的量子模拟。




▲ Abstract:

A large qubit capacity and an individual readout capability are two crucial requirements for large-scale quantum computing and simulation. As one of the leading physical platforms for quantum information processing, the ion trap has achieved a quantum simulation of tens of ions with site-resolved readout in a one-dimensional Paul trap and of hundreds of ions with global observables in a two-dimensional (2D) Penning trap. However, integrating these two features into a single system is still very challenging. Here we report the stable trapping of 512 ions in a 2D Wigner crystal and the sideband cooling of their transverse motion. Enabled by the site resolution in the single-shot measurement, we observe rich spatial correlation patterns in the quasi-adiabatically prepared ground states, which allows us to verify quantum simulation results by comparing the measured two-spin correlations with the calculated collective phonon modes and with classical simulated annealing. We further probe the quench dynamics of the Ising model in a transverse field to demonstrate quantum sampling tasks. Our work paves the way for simulating classically intractable quantum dynamics and for running noisy intermediate-scale quantum algorithms using 2D ion trap quantum simulators.

化学物理Chemical Physics

Acceleration of radiative recombination for efficient perovskite LEDs


▲ 作者:Mengmeng Li, Yingguo Yang, Zhiyuan Kuang, Chenjie Hao, Saixue Wang, Feiyue Lu, Zhongran Liu, Jinglong Liu, Lingjiao Zeng, Yuxiao Cai, Yulin Mao, Jingshu Guo, He Tian, Guichuan Xing, Yu Cao, Chao Ma, Nana Wang, Qiming Peng, Lin Zhu, Wei Huang & Jianpu Wang

▲ 链接:


▲ 摘要:




研究实现了具有创纪录峰值EQE为32.0%的钙钛矿LED,即使在100 mA cm?2的高电流密度下,效率仍然大于30.0%。这些发现为推进高效、高亮度钙钛矿LED的发展提供了有价值的见解。

▲ Abstract:

The increasing demands for more efficient and brighter thin-film light-emitting diodes (LEDs) in flat-panel display and solid-state lighting applications have promoted research into three-dimensional (3D) perovskites. These materials exhibit high charge mobilities and low quantum efficiency droop, making them promising candidates for achieving efficient LEDs with enhanced brightness. To improve the efficiency of LEDs, it is crucial to minimize nonradiative recombination while promoting radiative recombination. Various passivation strategies have been used to reduce defect densities in 3D perovskite films, approaching levels close to those of single crystals. However, the slow radiative (bimolecular) recombination has limited the photoluminescence quantum efficiencies (PLQEs) of 3D perovskites to less than 80%, resulting in external quantum efficiencies (EQEs) of LED devices of less than 25%. Here we present a dual-additive crystallization method that enables the formation of highly efficient 3D perovskites, achieving an exceptional PLQE of 96%. This approach promotes the formation of tetragonal FAPbI3 perovskite, known for its high exciton binding energy, which effectively accelerates the radiative recombination. As a result, we achieve perovskite LEDs with a record peak EQE of 32.0%, with the efficiency remaining greater than 30.0% even at a high current density of 100?mA?cm?2. These findings provide valuable insights for advancing the development of high-efficiency and high-brightness perovskite LEDs.

Atomic dynamics of electrified solid–liquid interfaces in liquid-cell TEM


▲ 作者:Qiubo Zhang, Zhigang Song, Xianhu Sun, Yang Liu, Jiawei Wan, Sophia B. Betzler, Qi Zheng, Junyi Shangguan, Karen C. Bustillo, Peter Ercius, Prineha Na

▲ 链接:


▲ 摘要:




▲ Abstract:

Electrified solid–liquid interfaces (ESLIs) play a key role in various electrochemical processes relevant to energy, biology and geochemistry. The electron and mass transport at the electrified interfaces may result in structural modifications that markedly influence the reaction pathways. For example, electrocatalyst surface restructuring during reactions can substantially affect the catalysis mechanisms and reaction products. Despite its importance, direct probing the atomic dynamics of solid–liquid interfaces under electric biasing is challenging owing to the nature of being buried in liquid electrolytes and the limited spatial resolution of current techniques for in situ imaging through liquids. Here, with our development of advanced polymer electrochemical liquid cells for transmission electron microscopy (TEM), we are able to directly monitor the atomic dynamics of ESLIs during copper (Cu)-catalysed CO2 electroreduction reactions (CO2ERs). Our observation reveals a fluctuating liquid-like amorphous interphase. It undergoes reversible crystalline–amorphous structural transformations and flows along the electrified Cu surface, thus mediating the crystalline Cu surface restructuring and mass loss through the interphase layer. The combination of real-time observation and theoretical calculations unveils an amorphization-mediated restructuring mechanism resulting from charge-activated surface reactions with the electrolyte. Our results open many opportunities to explore the atomic dynamics and its impact in broad systems involving ESLIs by taking advantage of the in situ imaging capability.


Reproducible graphene synthesis by oxygen-free chemical vapour deposition


▲ 作者:Jacob Amontree, Xingzhou Yan, Christopher S. DiMarco, Pierre L. Levesque, Tehseen Adel, Jordan Pack, Madisen Holbrook, Christian Cupo, Zhiying Wang, Dihao Sun, Adam J. Biacchi, Charlezetta E. Wilson-Stokes, Kenji Watanabe, Takashi Taniguchi, Cory R. Dean, Angela R. Hight Walker, Katayun Barmak, Richard Martel & James Hone

▲ 链接:


▲ 摘要:



经过干燥转移和氮化硼封装后,其室温电输运行为接近于剥离的石墨烯。石墨门控器件表现出良好的整数和分数量子霍尔效应。通过强调消除微量氧的重要性,新研究作为今后CVD系统的设计和运行提供了指导。由OF-CVD 合成的可重复性和质量的提高将广泛影响石墨烯的基础研究和应用。

▲ Abstract:

Chemical vapour deposition (CVD) synthesis of graphene on copper has been broadly adopted since the first demonstration of this process. However, widespread use of CVD-grown graphene for basic science and applications has been hindered by challenges with reproducibility and quality. Here we identify trace oxygen as a key factor determining the growth trajectory and quality for graphene grown by low-pressure CVD. Oxygen-free chemical vapour deposition (OF-CVD) synthesis is fast and highly reproducible, with kinetics that can be described by a compact model, whereas adding trace oxygen leads to suppressed nucleation and slower/incomplete growth. Oxygen affects graphene quality as assessed by surface contamination, emergence of the Raman D peak and decrease in electrical conductivity. Epitaxial graphene grown in oxygen-free conditions is contamination-free and shows no detectable D peak. After dry transfer and boron nitride encapsulation, it shows room-temperature electrical-transport behaviour close to that of exfoliated graphene. A graphite-gated device shows well-developed integer and fractional quantum Hall effects. By highlighting the importance of eliminating trace oxygen, this work provides guidance for future CVD system design and operation. The increased reproducibility and quality afforded by OF-CVD synthesis will broadly influence basic research and applications of graphene.

Work hardening in colloidal crystals


▲ 作者:Seongsoo Kim, Ilya Svetlizky, David A. Weitz & Frans Spaepen

▲ 链接:


▲ 摘要:




▲ Abstract:

Colloidal crystals exhibit interesting properties that are in many ways analogous to their atomic counterparts. They have the same crystal structures, undergo. Here we show that hard-sphere colloidal crystals exhibit work hardening. Moreover, despite their softness, the shear strength of colloidal crystals can increase and approach the theoretical limit for crystals, a value reached in very few other materials so far. We use confocal microscopy to show that the strength of colloidal crystals increases with dislocation density, and ultimately reaches the classic Taylor scaling behaviour for atomic materials, although hard-sphere interactions lack the complexity of atomic interactions. We demonstrate that Taylor hardening arises through the formation of dislocation junctions. The Taylor hardening regime, however, is established only after a transient phase, and it ceases when the colloidal crystals become so hard that the strain is localized within a thin boundary layer in which slip results from an unconventional motion of dislocations. The striking resemblance between colloidal and atomic crystals, despite the many orders of magnitude difference in particle size and shear modulus, demonstrates the universality of work hardening.

 打印  发E-mail给: 
相关新闻 相关论文

研究阐述钙钛矿量子点最新进展 7月福利!科学网APP论文&基金最新活动
让屋顶变白是保持城市凉爽的最好方法 他们心里有一盘棋:“精准设计”水稻种子