Our work on Nonlinear photocurrents in chiral semimetal is published in Physics Review B
拓撲半金屬中的非線性光電流蘊含了布洛赫波函數的量子幾何特徵及能帶拓撲性質,並為先進光伏技術的發展提供了新的可能。本團隊詹曜瑞博士透過改良的兆赫波發射光譜分析,成功表徵了手性多重半金屬 CoSi 的非線性光電導光譜。其結果揭示了一個較大的Shift current光電導(17 μA/V²),並確認了由於來自具有相反手性多重拓譜節點附近的強干涉非量子化貢獻,所導致的巨大injection current 光電導(167 μA/V²)。實驗結果亦識別出體相橫向偏極化的injection current與微弱的非局化光子拖曳效應(photon drag effect)。本研究不僅探討了手性過渡金屬單矽化物中光電流的非線性光學起源,還突顯出其透過各種非線性光學通道在中紅外光伏領域的應用潛力。
該研究獲選為《Physical Review B》編輯推薦文章。
Our work on momentum-dependent SFG spectroscopy of charged water interfaces is published on Science Advances
Interface-specific hydrogen (H)–bonding network of water directly controls the energy transfer and chemical reaction pathway at many charged aqueous interfaces, yet to characterize these bonded water layer structures remains a challenge. We now develop a sum-frequency spectroscopic scheme with varying photon momenta as an all-optic solution for retrieving the vibrational spectra of the bonded water layer and the ion diffuse layer and, hence, microscopic structural and charging information about an interface. Application of the method to a model surfactant-water interface reveals a hidden weakly donor H-bonded water species, suggesting an asymmetric hydration-shell structure of fully solvated surfactant headgroups. In another application to a zwitterionic phosphatidylcholine lipid monolayer–water interface, we find a highly polarized bonded water layer structure associating to the phosphatidylcholine headgroup, while the diffuse layer contribution is experimentally proven to be negligible. Our all-optic method offers an in situ microscopic probe of electrochemical and biological interfaces and the route toward future imaging and ultrafast dynamics studies.