Development of a UV-laser Based Ultra-High Resolution Angle-Resolved Photoemission Capability for Electronic Structure Studies

开发基于紫外激光的超高分辨率角分辨光电发射能力，用于电子结构研究

• 批准号: 9704045
• 负责人: Daniel Dessau
• 金额: $ 29.08万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9704045&HistoricalAwards=false
• 关键词: Development; UV; laser; Based; Ultra

9704045 Dessau A state-of-the-art high resolution photoemission capability will be developed at the University of Colorado with support from The Division of Materials Research and The Office of Multidisciplinary Activities. A novel and particularly powerful aspect of the instrumentation will be the development and usage of a high power femtosecond UV laser system as an excitation source for photoemission experiments of electronic materials. The UV-laser system will provide: (1) a photon flux orders of magnitude higher than is achievable by other means, including the best wiggler or undulator sources at a synchrotron. (2) Very high energy resolution (1-10 meV), depending upon the temporal length of the pulses. (3) Greater ease in controlling the photon polarization (linear, circular, etc.), which is very helpful for obtaining the symmetry of the electronic states. (4) Much greater bulk sensitivity because the electron mean free paths get very long at low kinetic energies. For studies of the bulk electronic structure, this will overcome one of the major difficulties of photoemission today, and open up the technique to the study of many materials systems which have not to date yielded high enough quality surfaces for reliable photoemission experiments. (5) Pump-Probe based photoemission which will enable us to (a) Study the unoccupied levels near the Fermi energy. This may replace inverse photoemission as the too of choice for this purpose, as inverse photoemission suffers from poor resolution (a few tenths of an eV), low count rates, and is damaging to a sample surface. (b) Study the dynamics of the system by varying the delay between the pump and the probe beams. The system will make use of the most advanced electron spectroscopic and laser instrumentation. To our knowledge, this powerful combination does not currently exist anywhere in the world. The requested instrumentation will also fill a hole in the techniques available in the greater Boulder area, and will be available to the local scientific community. ***

小行星9704045德绍 在材料研究司和多学科活动办公室的支持下，科罗拉多大学将开发最先进的高分辨率光电发射能力。一个新的和特别强大的方面的仪器将是一个高功率飞秒紫外激光系统的开发和使用作为激发源的电子材料的光电发射实验。 紫外激光系统将提供： (1)光子通量的数量级高于通过其它装置（包括同步加速器处的最佳摆动器或波荡器源）可实现的数量级。 (2)非常高的能量分辨率（1-10 meV），取决于脉冲的时间长度。 (3)更容易控制光子偏振（线性、圆形等），这对于获得电子态的对称性是非常有帮助的。 (4)更大的体积灵敏度，因为电子平均自由程在低动能时变得非常长。 对于体电子结构的研究，这将克服当今光电发射的主要困难之一，并将该技术开放给许多材料系统的研究，这些材料系统迄今为止还没有产生足够高质量的表面用于可靠的光电发射实验。 (5)基于泵浦-探测的光电发射技术， (a)研究费米能级附近的空能级。 这可能会取代反向光电发射作为太多的选择 为此目的，由于逆光电发射受到不良的影响， 分辨率（十分之几eV），低计数率， 破坏样品表面。 (b)研究系统的动态变化， 泵浦光束和探测光束之间的延迟。 该系统将利用最先进的电子光谱和激光仪器。 据我们所知，这种强大的组合目前在世界任何地方都不存在。 所要求的仪器也将填补大博尔德地区现有技术的空白，并将提供给当地科学界。 ***