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

9503883坎普扎诺角分辨光电发射技术是目前确定材料中电子的能量-动量关系的唯一方法，也就是确定材料的完整电子结构。最近，我们极大地改进了ARPES技术，从以前典型的~30 meV分辨率提高到8 meV。这一改进为理解新材料，特别是具有大单胞的人造材料开辟了新的可能性。这是因为在具有大单胞的材料中，电子状态在能量上是紧密分布的，需要极高的分辨率。我们打算研究的例子有高温和有机超导体，金属、磁性和半导体多层膜中的量子限制等。虽然我们在提高能量分辨率方面取得了很大进展，但在动量分辨率方面却不是这样。新的人造大单元电池材料具有非常小的布里渊区。幸运的是，这个问题本质上只是几何问题：动量分辨率可以通过简单地限制电子分析器的接受角度来提高。然而，由于计数率随孔径的平方而减小，因此需要更高的光通量。%有了这个奖项，我们将在威斯康星大学麦迪逊分校的同步辐射中心建造一台高通量、高分辨率正入射单色仪的基于波荡器的光束线；S客座研究员计划。该仪器不仅将为研究电子结构开辟新的可能性，而且还将减轻SRC现有的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. ***