题 目：The departure time of electrons in strong-field ionization
报告人：Manfred Lein 教授
主持人：倪宏程研究员
时 间：2020年10月29日17:00
地 点：腾讯会议（会议ID：918 247 205）
报告人简介：
Manfred Lein教授2001年博士毕业于德国Würzburg大学，2001年至2004年先后在英国伦敦帝国学院和德国马克斯普朗克复杂系统物理研究所从事博士后研究，2004年至2006年担任德国马克斯普朗克核物理研究所课题组组长，2006年至2009年担任德国Kassel大学副教授，2009年至今担任德国汉诺威大学教授。Manfred Lein教授的研究兴趣主要为激光与物质作用理论、含时密度泛函理论、计算物理等，担任Physical Review A、Journal of Physics B等期刊编委，以及德国科学基金会QUTIF重大科研项目首席科学家。
报告内容简介：
When atoms or molecules are ionized by a short intense laser pulse, the variation of the electric field strength on a subcycle time scale implies that the outgoing electrons depart preferentially around the maximum of the electric field. We will discuss several methods to observe the electron departure time with attosecond precision. From previous work it is well known that the ionization time in a near-circularly polarized pulse can be measured using the attoclock technique, where the electron emission angle is mapped to the departure time by an appropriate model. On the other hand, two-color high-harmonic generation, i.e. measurement of the emitted extreme violet radiation upon irradiation of a strong fundamental field and a weak additional probe field, is a tool to measure the ionization time in a linearly polarized field. We will see that a bicircular ionizing field, i.e. a waveform composed of two different circularly polarized colors, offers the possibility to compare the attoclock and two-color method for one and the same ionizing field. For the two-color high-harmonic generation scheme, we find that a high-frequency probe field rather than the commonly used second-harmonic field is suitable for measuring the shift of the electron departure time due to the Coulomb binding potential.