Fully differential studies for two-photon non-sequential double ionization of helium using a reaction microscope at FLASH

使用 FLASH 反应显微镜对氦气双光子非顺序双电离进行全微分研究

• 批准号: 58058708
• 负责人: Dr. Yuhai Jiang
• 金额: --
• 依托单位: Max-Planck-Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/58058708?language=en
• 关键词: Fully; differential; studies; two; photon

Two-photon induced double ionization (TP-DI) of helium is of decisive and fundamental importance to advance non-linear theories and explore electron-electron correlations, particularly for non-sequential ionization. Using the free electron laser (FEL) at Hamburg (FLASH), the only fourth generation radiation source operational world wide, delivering unprecedented intensities (~1013-1016 W/cm2) at ultra-short pulse durations (~30 fs and less) in combination with the most advanced multi-particle detection system - the Heidelberg reaction microscope - we studied for the first time He2+ recoil-ion momentum distributions (RIMD) at a photon energy of 44 eV, one of the goals of the previous proposal. The results represent evidence for preferential back-to-back emission of two electrons with almost equal energy sharing, which unambiguously distinguishes it from sequential ionization of Ne observed at 44 eV by our fully differential measurements. However, the present RIMD can not finally benchmark significant deviations in differential as well as total cross sections between the predictions of different recent advanced calculations and, therefore, fully differential measurements for direct TP-DI of He are highly demanded, an ultimate aim of this proposal. These studies are indispensable for the understanding of more complex situations when FEL-radiation interacts with many-electron atoms, molecules, clusters, surfaces or bulk-matter in the extreme ultraviolet regime.

氦的双光子诱导双电离（TP-DI）对于推进非线性理论和探索电子-电子相关性（特别是对于非顺序电离）具有决定性和根本性的重要性。使用汉堡 (FLASH) 的自由电子激光器 (FEL)，这是全球唯一运行的第四代辐射源，在超短脉冲持续时间（~30 fs 及以下）下提供前所未有的强度（~1013-1016 W/cm2），并结合最先进的多粒子检测系统 - 海德堡反应显微镜 - 我们首次研究了 He2+ 反冲离子 光子能量为 44 eV 时的动量分布 (RIMD)，这是之前提案的目标之一。结果代表了两个电子以几乎相等的能量共享优先背对背发射的证据，这明确地将其与我们通过全差分测量在 44 eV 处观察到的 Ne 的顺序电离区分开来。然而，目前的 RIMD 无法最终对最近不同先进计算的预测之间微分截面和总截面的显着偏差进行基准测试，因此，强烈需要对 He 的直接 TP-DI 进行全微分测量，这是该提案的最终目标。这些研究对于理解 FEL 辐射在极紫外区域与多电子原子、分子、簇、表面或块体物质相互作用时的更复杂情况是必不可少的。