Construction of an Undulator Beamline Using a Normal Incidence Monochromator for Ultra-High Resolution Photoemission and Other Studies at NSF's Synchrotron Radiation Center

角分辨光电发射技术（ARPES）是目前唯一确定材料中电子的能量-动量关系，即材料的完整电子结构的方法。近年来，我们将ARPES的分辨率从原来的~ 30mev大幅提高到8mev。这一改进为理解新材料开辟了新的可能性，特别是具有大单位电池的人造材料。这是因为在具有大单元电池的材料中，折衷态的能量间隔很近，需要极高的分辨率。我们建议研究的例子是高温和有机超导体，金属，磁性和半导体多层中的量子限制等。虽然我们在提高能源分辨率方面取得了很大进展，但在动量分辨率方面却没有取得同样的进展。这种新型的人造大晶胞材料具有非常小的布里渊区。幸运的是，这个问题只是几何性质的：动量分辨率可以通过简单地限制电子分析仪的接收角度来提高。然而，由于计数率随着孔径的平方而减小，因此需要更高的光子束通量。有了这份合同，我们将在威斯康星大学麦迪逊分校的同步辐射中心建立一个基于波动器的光束线，该光束线具有高通量、高分辨率的正常入射单色仪；s客座调查员计划。该仪器不仅将为电子结构的研究开辟新的可能性，而且还将减轻SRC现有4m NIM光束线的沉重负担。* * *

9503883 Campuzano The technique of Angle-Resolved Photoemission (ARPES) is currently the only method of determining the energy - momentum relationship of electrons in materials, that is, the complete electronic structure of materials. Recently, we have dramatically improved the technique of ARPES from its previous typical resolution of ~30 meV to 8 meV. This improvement opens up new possibilities in understanding new materials, particularly the man-made ones with large unit cells. This is because in materials with large unit cells the eclectron states are closely spaced in energy, requiring extreme resolution. Examples of what we propose to study are the high temperature and organic superconductors, quantum confinement in metallic, magnetic, and semiconducting multilayers, etc. Although we have made great strides in improving the energy resolution, the same cannot be said about momentum resolution. The new man- made large unit cell materials have very small Brillouin zones. This problem is fortunately only geometrical in nature: the momentum resolution can be improved by simply restricting the acceptance angle of the electron analyzer. However, since the counting rate decreases as the square of that aperture, higher photon beam flux is required. %%% With this award we will construct an undulator-based beamline with a high throughput-high resolution normal incidence monochromator at the University of Wisconsin-Madison's Synchrotron Radiation Center;s Guest Investigator Program. The instrument will not only open new possibilities in the study of electronic structure, but will also relieve the heavy burden placed on the existing 4m NIM beamline at SRC. ***