| 1 | Highly efficient and aberration-free off-plane grating spectrometer and monochromator for EUV—soft X-ray applications显示文摘We demonstrate a novel flat-field,dual-optic imaging EUV—soft X-ray spectrometer and monochromator that attains an unprecedented throughput efficiency exceeding 60%by design,along with a superb spectral resolution ofλ/Δλ>200 accomplished without employing variable line spacing gratings.Exploiting the benefits of the conical diffraction geometry,the optical system is globally optimized in multidimensional parameter space to guarantee optimal imaging performance over a broad spectral range while maintaining circular and elliptical polarization states at the first,second,and third diffraction orders.Moreover,our analysis indicates minimal temporal dispersion,with pulse broadening confined within 80 fs tail-to-tail and an FWHM value of 29 fs,which enables ultrafast spectroscopic and pump-probe studies with femtosecond accuracy.Furthermore,the spectrometer can be effortlessly transformed into a monochromator spanning the EUV—soft X-ray spectral region using a single grating with an aberration-free spatial profile.Such capability allows coherent diffractive imaging applications to be conducted with highly monochromatic light in a broad spectral range and extended to the soft X-ray region with minimal photon loss,thus facilitating state-of-the-art imaging of intricate nano-and bio-systems,with a significantly enhanced spatiotemporal resolution,down to the nanometer–femtosecond level. | Jie Li Kui Li Xiaoshi Zhang Dimitar Popmintchev Hao Xu Yutong Wang Ruixuan Li Guangyin Zhang Jiyue Tang Jin Niu Yongjun Ma Runyu Meng Changjun Ke Jisi Qiu Yunfeng Ma Tenio Popmintchev Zhongwei Fan | 2024 | Light(Science & Applications)2024，13，1： | 0 |
| 2 | Two-dimensional Dirac materials:Tight-binding lattice models and material candidates显示文摘The discovery of graphene has led to the devotion of intensive efforts,theoretical and experimental,to produce two-dimensional(2D)materials that can be used for developing functional materials and devices.This work provides a brief review of the recent developments in the lattice models of 2D Dirac materials and their relevant real material counterparts that are crucial for understanding the origins of 2D Dirac cones in electronic band structures as well as their material design and device applications.We focus on the roles of lattice symmetry,atomic orbital hybridization,and spin-orbit coupling in the presence of a Dirac cone.A number of lattice models,such as honeycomb,kagome,ruby,star,Cairo,and line-centered honeycomb,with different symmetries are reviewed based on the tight-binding approach.Inorganic and organic 2D materials,theoretically proposed or experimentally synthesized to satisfy these 2D Dirac lattice models,are summarized. | Runyu Fan Lei Sun Xiaofei Shao Yangyang Li Mingwen Zhao | 2023 | ChemPhysMater2023，2，1： | 0 |
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