Picosecond resolution of phonon dynamics with pulsed synchrotron radiation

脉冲同步辐射声子动力学的皮秒分辨率

• 批准号: 136195485
• 负责人: Privatdozent Dr. Anton Plech
• 金额: --
• 依托单位: Laboratorium für Applikationen der Synchrotronstrahlung (LAS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/136195485?language=en
• 关键词: Picosecond; resolution; phonon; dynamics; pulsed

In the first part of the research project we proposed to study the lattice dynamics of semicon-ductor crystals, in particular multilayered nanostructures as well as ferroelectric lattice excita-tions by using ultrafast time-resolved x-ray scattering. A novel approach was proposed which uses the short pulse x-ray emission at the synchrotron ANKA and using its 500 MHz repeti-tion rate for a pump-probe setup. Radiation pulses emitted at ANKA can be extremely short (down to 1 ps) when using the so-called low-alpha mode of operation. The setup has been completed within the past period and is operational. Within this proposal we want to conduct ASOXS experiments on isotopically pure multilayers of silicon, respectively germanium. The phonon motion should reveal information about the nature of the phonon barrier in these mul-tilayered systems that are proposed to serve as thermoelectric materials. With ASOXS we also get access to the dynamics of the local motion in barium titanate ferroelectric crystals. The local motion and symmetry should give an independent access to the nature of the ferroelectric phase transition and solve a long-standing problem on the description of dis-placive versus diffusive ferroelectric order.

在该研究项目的第一部分中，我们建议通过使用超快时间分辨 X 射线散射来研究半导体晶体的晶格动力学，特别是多层纳米结构以及铁电晶格激发。提出了一种新颖的方法，该方法使用同步加速器 ANKA 的短脉冲 X 射线发射，并使用其 500 MHz 重复率进行泵浦探针设置。当使用所谓的低阿尔法操作模式时，ANKA 发射的辐射脉冲可能非常短（低至 1 ps）。该设置已在过去一段时间内完成并可运行。在这个提案中，我们希望分别对硅和锗的同位素纯多层进行 ASOXS 实验。声子运动应该揭示有关这些被提议用作热电材料的多层系统中声子势垒性质的信息。通过 ASOXS，我们还可以获得钛酸钡铁电晶体局部运动的动力学。局部运动和对称性应该能够独立地了解铁电相变的性质，并解决描述位移与扩散铁电序的长期存在的问题。