Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interact...Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump–probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photoinduced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light–free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams.展开更多
We report the observation of a magnetic transition at the temperature about 56 K,through the high-pressure heat capacity and magnetic susceptibility measurements on the samples that have been claimed to be a nearroom-...We report the observation of a magnetic transition at the temperature about 56 K,through the high-pressure heat capacity and magnetic susceptibility measurements on the samples that have been claimed to be a nearroom-temperature superconductor[Dasenbrock-Gammon et al.Nature 615,244(2023)].Our results show that this magnetic phase is robust against pressure up to 4.3 GPa,which covers the critical pressure of boosting the claimed superconductivity.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.U22A6005 and 12074408)the National Key Research and Development Program of China (Grant No.2021YFA1301502)+7 种基金Guangdong Major Scientific Research Project (Grant No.2018KZDXM061)Youth Innovation Promotion Association of CAS (Grant No.2021009)Scientific Instrument Developing Project of the Chinese Academy of Sciences (Grant Nos.YJKYYQ20200055,ZDKYYQ2017000,and 22017BA10)Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant Nos.XDB25000000 and XDB33010100)Beijing Municipal Science and Technology Major Project (Grant No.Z201100001820006)IOP Hundred Talents Program (Grant No.Y9K5051)Postdoctoral Support Program of China (Grant No.2020M670501)the Synergetic Extreme Condition User Facility (SECUF)。
文摘Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump–probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photoinduced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light–free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403900 and 2021YFA1401800)the National Natural Science Foundation of China(Grant Nos.U2032214,12122414,12104487,and 12004419)+2 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)supports from the Youth Innovation Promotion Association of the CAS(Grant No.2019008)the China Postdoctoral Science Foundation(Grant No.E0BK111)。
文摘We report the observation of a magnetic transition at the temperature about 56 K,through the high-pressure heat capacity and magnetic susceptibility measurements on the samples that have been claimed to be a nearroom-temperature superconductor[Dasenbrock-Gammon et al.Nature 615,244(2023)].Our results show that this magnetic phase is robust against pressure up to 4.3 GPa,which covers the critical pressure of boosting the claimed superconductivity.
