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报告题目：Illuminating the ultrafast nanoworld with lightwave-driven scanning tunnelling microscopy
报告时间：2024-05-14 14:30
报告人： Lukas Kastner
Universität Regensburg
报告地点：翔安校区能源材料大楼3号楼会议室2
报告摘要：
The fundamental building blocks that constitute all matter – animate and inanimate – interact on extremely small atomic distances (1 Å = 10-10 m) and timescales (1 fs = 10-15 s). Lightwave-driven scanning tunnelling microscopy (LW-STM) can be used to observe and even control these elementary dynamics. This approach complements the remarkable atomic spatial resolution of conventional STM with a simultaneous ultrashort temporal resolution as short as 100 fs by employing the fastest transient bias voltage nature has to offer: the oscillating carrier wave of light.
Employing this sophisticated technique, we capture a nanomovie of the sub-picosecond (1 ps = 10-12 s) coherent dynamics of a single-molecule rotator upon the application of local ultrafast forces, demonstrating the coherent control over a molecular switching reaction. Moreover, the exact shape of the electromagnetic near-field waveform within the atomic-scale tunnelling junction is traced quantitatively for the first time, paving the way for the predictive design of nanophotonic structures.
As all motion is intricately linked to changes in the energetic structure of a system, we aimed to further elucidate nanoscopic phenomena by visualising the temporal evolution of energy levels after ultrafast excitation. To this end, we investigate an atomic vacancy within a tungsten-diselenide monolayer using LW-STM. The first observation of shifts of localised energy levels at an atomic vacancy with combined Ångström spatial, sub-picosecond temporal and 10 meV energy resolution is demonstrated.
As an outlook, a cutting-edge setup further enhancing the capabilities of LW-STM is introduced. A custom-built laser setup consisting of a source for single-cycle mid-infrared and tuneable ultrashort pump pulses will allow for the study of pump-induced changes on timescales of 10 fs.
报告人简介：
报告人Lukas Kastner博士简介如下：
2018年6月–2023年12月：博士毕业于雷根斯堡大学物理系；导师：R. Huber教授；
2016年10月–2017年10月：硕士毕业于伦敦帝国理工学院；导师：J. Nelson教授
2013年10月–2016年8月：本科毕业于雷根斯堡大学；导师：R. Huber教授
近期主要代表论著：
1、Ultrafast atomic-scale scanning tunnelling spectroscopy of a single vacancy in a monolayer crystal. C. Roelcke*, L. Z. Kastner* et al., Nature Photonics (2024) * equal contributions.
2、Scalable high-repetition-rate sub-half-cycle terahertz pulses from spatially indirect inter-band transitions. C. Meineke, M. Prager, J. Hayes, Q. Wen, L. Z. Kastner et al., Light: Science & Applications (2022)
3、Quantitative sampling of atomic-scale electromagnetic waveforms. D. Peller, C. Roelcke, L. Z. Kastner et al., Nature Photonics (2021)
4、Sub-cycle atomic-scale forces coherently control a single-molecule switch. D. Peller, L. Z. Kastner et al., Nature (2020)
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