編譯|未玖
Science, 12 JUL 2024, VOL 385, ISSUE 6705
《科學》2024年7月12日，第385卷，6705期
物理學Physics
Structured electrons with chiral mass and charge
具有手性質量和電荷的結構電子
▲ 作者：YIQI FANG, JOEL KUTTRUFF, DAVID NABBEN, AND PETER BAUM
▲鏈接：
https://www.science.org/doi/10.1126/science.adp9143
▲摘要：
手性是一種在基礎物理學、材料科學、化學、光學和光譜學中具有廣泛關聯的現象。
這項工作中，研究組證明了自由電子可通過激光場周期轉化為質量和電荷的右旋或左旋。與相位渦旋光束相比，該電子保持了平坦的德布羅意波，但從其時空期望值的形狀獲得了相應的手性。
通過阿秒門控測量波函數密度，揭示了具有左旋或右旋螺距的線圈和雙線圈的三維形狀。具有此類或相關手性幾何結構的工程基本粒子可應用于手性傳感、自由電子量子光學、粒子物理學或電子顯微鏡等領域。
▲ Abstract：
Chirality is a phenomenon with widespread relevance in fundamental physics, material science, chemistry, optics, and spectroscopy. In this work, we show that a free electron can be converted by the field cycles of laser light into a right-handed or left-handed coil of mass and charge. In contrast to phase-vortex beams, our electrons maintained a flat de Broglie wave but obtained their chirality from the shape of their expectation value in space and time. Measurements of wave function densities by attosecond gating revealed the three-dimensional shape of coils and double coils with left-handed or right-handed pitch. Engineered elementary particles with such or related chiral geometries should be useful for applications in chiral sensing, free-electron quantum optics, particle physics or electron microscopy.
材料科學Materials Science
A crystal capping layer for formation of black-phase FAPbI3 perovskite in humid air
在潮濕空氣中形成黑相FAPbI3鈣鈦礦的晶體覆蓋層
▲ 作者：YU ZOU, WENJIN YU, HAOQING GUO, QIZHI LI, XIANGDONG LI, LIANG LI, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.adn9646
▲摘要：
黑相甲脒碘化鉛（α-FAPbI3）鈣鈦礦是光伏應用的理想相，但水會引發諸如δ-FAPbI3光惰性雜質相的形成。
研究組表明，鈣鈦礦制造的經典溶劑系統加劇了這種可重復性挑戰。傳統配位溶劑二甲亞砜（DMSO）因其吸濕性，在高相對濕度（RH）條件下促進了δ-FAPbI3的形成。
研究組引入含氯有機分子來形成覆蓋層，阻止水分滲透，同時保留基于DMSO的配合物來調節晶體生長。所得鈣鈦礦太陽能電池在20%至60% RH下的能量轉換效率>24.5%，在80% RH下為23.4%。在最大功率點運行500小時后，未封裝設備在空氣中（40至60% RH）仍保留96%的初始性能。
▲ Abstract：
Black-phase formamidinium lead iodide (α-FAPbI3) perovskites are the desired phase for photovoltaic applications, but water can trigger formation of photoinactive impurity phases such as δ-FAPbI3. We show that the classic solvent system for perovskite fabrication exacerbates this reproducibility challenge. The conventional coordinative solvent dimethyl sulfoxide (DMSO) promoted δ-FAPbI3 formation under high relative humidity (RH) conditions because of its hygroscopic nature. We introduced chlorine-containing organic molecules to form a capping layer that blocked moisture penetration while preserving DMSO-based complexes to regulate crystal growth. We report power conversion efficiencies of >24.5% for perovskite solar cells fabricated across an RH range of 20 to 60%, and 23.4% at 80% RH. The unencapsulated device retained 96% of its initial performance in air (with 40 to 60% RH) after 500-hour maximum power point operation.
Partitioning polar-slush strategy in relaxors leads to large energy-storage capability
弛豫器的極性雪泥態區塊化策略可實現大儲能容量
▲ 作者：LIANG SHU, XIAOMING SHI, XIN ZHANG, ZIQI YANG, WEI LI, YUNPENG MA, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.adn8721
▲摘要：
弛豫鐵電（RFE）薄膜因其高能量密度（Ue）和高效率而成為小型化高功率電子系統頗有前景的儲能候選材料。然而，將其Ue提高到200 J/cm3焦耳以上頗具挑戰性，這限制了RFE在下一代儲能設備中的應用潛力。
研究組在RFE中實施了一種極性雪泥態區塊化策略來突破Ue的界限。在相場模擬的指導下，通過抑制非極性立方矩陣和引入高絕緣網絡，設計并制備了具有隔離極性雪泥態團簇的Bi(Mg0.5Ti0.5)O3-SrTiO3基高性能RFE薄膜。
可逆極化和擊穿強度的同時增強導致Ue達到202 J/cm3，效率高達79%。該策略為下一代高性能電介質提供了設計自由度。
▲ Abstract：
Relaxor ferroelectric (RFE) films are promising energy-storage candidates for miniaturizing high-power electronic systems, which is credited to their high energy density (Ue) and efficiency. However, advancing their Ue beyond 200 joules per cubic centimeter is challenging, limiting their potential for next-generation energy-storage devices. We implemented a partitioning polar-slush strategy in RFEs to push the boundary of Ue. Guided by phase-field simulations, we designed and fabricated high-performance Bi(Mg0.5Ti0.5)O3-SrTiO3–based RFE films with isolated slush-like polar clusters, which were realized through suppression of the nonpolar cubic matrix and introduction of highly insulating networks. The simultaneous enhancement of the reversible polarization and breakdown strength leads to a Ue of 202 joules per cubic centimeter with a high efficiency of ~79%. The proposed strategy provides a design freedom for next-generation high-performance dielectrics.
化學Chemistry
Resetting tropospheric OH and CH4 lifetime with ultraviolet H2O absorption
利用紫外水吸收重設對流層OH和CH4壽命
▲ 作者：MICHAEL J. PRATHER AND LEI ZHU
▲鏈接：
https://www.science.org/doi/10.1126/science.adn0415
▲摘要：
甲基氯仿（一種禁用的消耗臭氧物質）的衰變提供了對流層羥基自由基（OH）平均豐度的明確觀測指標。幾乎所有當前的全球化學模型都計算出約15%的OH過量，從而導致甲烷損失過快。甲烷是一種短暫的氣候因子，對實現全球變暖目標至關重要，這一錯誤影響了人們對氣候變化的模型預測。
研究組對紫外線區（290至350納米）水汽吸收的新觀測表明，近地表熱帶大氣中的關鍵光解速率下降了8%至12%，導致陽光減少。化學輸運模型中納入這一新機制僅能減少4%的OH和甲烷損失，但結合其他提出的機制，如對流層鹵素化學（7%），研究組有望解決這一難題。
▲ Abstract：
The decay of methyl chloroform, a banned ozone-depleting substance, has provided a clear observational metric of mean tropospheric hydroxyl radical (OH) abundance. Almost all current global chemistry models calculate about 15% too much OH and thus too rapid methane loss. Methane is a short-lived climate forcer, critical to achieving global warming targets, and this error affects our model projections of climate change. New observations of water vapor absorption in the ultraviolet region (290 to 350 nanometers) imply reductions in sunlight with key photolysis rates decreasing by 8 to 12% in the near-surface tropical atmosphere. Incorporation of this new mechanism in a chemistry-transport model reduces OH and methane loss by only 4%, but combined with other proposed mechanisms, such as tropospheric halogen chemistry (7%), we may be able to resolve this conundrum.
Programmed alternating current optimization of Cu-catalyzed C-H bond transformations
銅催化C-H鍵轉化的可編程交流電優化
▲ 作者：LI ZENG, QINGHONG YANG, JIANXING WANG, XIN WANG, PENGJIE WANG, SHENGCHUN WANG, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.ado0875
▲摘要：
直流（DC）電合成技術在過去一個世紀里經歷了不斷的優化，在各種工業工藝中起著舉足輕重的作用。交流（AC）電合成具有極性反轉和周期性波動的特征，或有利于多種化學反應，但設備、原理和應用場景進展較慢。
在這項工作中，研究組介紹了一種可編程交流（pAC）電合成協議，可系統地調整電流、頻率和占空比。代表性pAC波形的應用促進了在DC和化學氧化條件下表現不佳的交叉偶聯和雙官能化反應中的銅催化碳-氫鍵裂解。
此外，觀察不同波形應用下的催化劑動態變化為人們提供了機理見解。
▲ Abstract：
Direct current (DC) electrosynthesis, which has undergone optimization over the past century, plays a pivotal role in a variety of industrial processes. Alternating current (AC) electrosynthesis, characterized by polarity reversal and periodic fluctuations, may be advantageous for multiple chemical reactions, but apparatus, principles, and application scenarios remain underdeveloped. In this work, we introduce a protocol for programmed AC (pAC) electrosynthesis that systematically adjusts currents, frequencies, and duty ratios. The application of representative pAC waveforms facilitates copper-catalyzed carbon-hydrogen bond cleavage in cross-coupling and difunctionalization reactions that exhibit suboptimal performance under DC and chemical oxidation conditions. Moreover, observing catalyst dynamic variation under diverse waveform applications provides mechanistic insight.
地球科學Earth Science
Stratospheric air intrusions promote global-scale new particle formation
平流層空氣流入促進全球尺度新粒子的形成
▲ 作者：JIAOSHI ZHANG, XIANDA GONG, EWAN CROSBIE, GLENN DISKIN, KARL FROYD, SAMUEL HALL, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.adn2961
▲摘要：
自由對流層中新粒子的形成是全球云凝結核的主要來源。主流觀點認為，在自由對流層中，新粒子主要在對流云外流中形成。
研究組利用全球觀測提出了另一種機制。結果發現，在平流層空氣流入事件中，下降且富含臭氧的平流層空氣與更濕潤的自由對流層背景混合導致羥基自由基（OH）濃度升高。
這種混合在對流層頂附近最為普遍，那里二氧化硫（SO2）的混合比率較高。SO2和OH水平共同升高導致硫酸濃度升高，促進顆粒形成。這種新粒子的形成頻率高，地理分布范圍廣，是中緯度自由對流層的重要粒子來源。
▲ Abstract：
New particle formation in the free troposphere is a major source of cloud condensation nuclei globally. The prevailing view is that in the free troposphere, new particles are formed predominantly in convective cloud outflows. We present another mechanism using global observations. We find that during stratospheric air intrusion events, the mixing of descending ozone-rich stratospheric air with more moist free tropospheric background results in elevated hydroxyl radical (OH) concentrations. Such mixing is most prevalent near the tropopause where the sulfur dioxide (SO2) mixing ratios are high. The combination of elevated SO2 and OH levels leads to enhanced sulfuric acid concentrations, promoting particle formation. Such new particle formation occurs frequently and over large geographic regions, representing an important particle source in the midlatitude free troposphere.