Berntsen M H, Götberg O, Tjernberg O
Materials Physics, KTH Royal Institute of Technology, S-16440 Kista, Sweden.
Rev Sci Instrum. 2011 Sep;82(9):095113. doi: 10.1063/1.3637464.
We present an experimental setup for laser-based angle-resolved time-of-flight photoemission. Using a picosecond pulsed laser, photons of energy 10.5 eV are generated through higher harmonic generation in xenon. The high repetition rate of the light source, variable between 0.2 and 8 MHz, enables high photoelectron count rates and short acquisition times. By using a time-of-flight analyzer with angle-resolving capabilities, electrons emitted from the sample within a circular cone of up to ±15° can be collected. Hence, simultaneous acquisition of photoemission data for a complete area of the Brillouin zone is possible. The current photon energy enables bulk sensitive measurements, high angular resolution, and the resulting covered momentum space is large enough to enclose the entire Brillouin zone in cuprate high-T(c) superconductors. Fermi edge measurements on polycrystalline Au shows an energy resolution better than 5 meV. Data from a test measurement of the Au(111) surface state are presented along with measurements of the Fermi surface of the high-T(c) superconductor Bi(2)Sr(2)CaCu(2)O(8 + δ) (Bi2212).
我们展示了一种基于激光的角分辨飞行时间光电子能谱实验装置。使用皮秒脉冲激光器,通过氙气中的高次谐波产生能量为10.5 eV的光子。光源的高重复频率在0.2至8 MHz之间可变,可实现高的光电子计数率和短的采集时间。通过使用具有角分辨能力的飞行时间分析仪,可以收集从样品发射出的、在高达±15°的圆锥范围内的电子。因此,可以同时采集布里渊区完整区域的光电子能谱数据。当前的光子能量能够进行体敏感测量、高角分辨率测量,并且所覆盖的动量空间足够大,足以包围铜酸盐高温超导体中的整个布里渊区。对多晶金的费米边测量显示能量分辨率优于5 meV。给出了金(111)表面态的测试测量数据以及高温超导体Bi(2)Sr(2)CaCu(2)O(8 + δ)(Bi2212)费米面的测量数据。