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shmily505铜虫 (正式写手)
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[求助]
诚求，“专业翻译”下面两段话
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1.Field emission tips are extremely high brightness emitters with large transverse coherence length and small energy spread. They are therefore excellent sources for interferometry experiments such as electron holography and coherent electron diffraction. Femtosecond field emission sources are being developed by triggering electron emission with ultrafast laser pulses. These sources have extremely small emission areas in comparison with existing ultrafast electron sources based on flat photocathodes and should therefore lead to better resolution for diffraction and imaging. Furthermore, the small source size leads to the high transverse coherence required for electron interferometry and holography. Ultrafast lasertriggered tips promise to extend the full range of electron microscopy imaging techniques to the femtosecond time scale, creating tools for the study of chemical and physical transformations of materials with atomic-scale resolution. 2.A number of areas have already benefited from lasertriggered emission from sharp tips. Optical field enhancement at the tip apex has allowed exploration of strong field physics in solid-state systems without the need for laser amplifiers. Due to the extreme sensitivity of current to the light intensity at the emission site, field emission tips have been used to study the temporal dynamics of the optical near field induced by the tip itself and map optical fields in nearby nanostructures with nanometric spatial resolution. Ultrafast laser-triggered emission has also been used as a source of electron pulses for experiments that verified the dispersionless nature of the Aharonov-Bohm effect and is being developed as an electron source for ultrafast scanning electron microscopy. These sources could also enable laser-based electron accelerators and a tabletop ultrafast x-ray microfocus source. [ Last edited by shmily505 on 2012-9-3 at 11:01 ] |
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