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兰州大学110周年校庆年系列活动之太阳成网址2138a“格致•创新”论坛2019年第四十期——Klavs Hansen教授

发布日期:2019-09-23 作者:马致兰    编辑:马致兰    来源:理论物理交流平台

应兰州大学物理科学与技术学院、萃英学院、理论物理交流平台邀请,天津大学Klavs Hansen教授将来我校进行学术合作交流并做学术报告,欢迎广大师生参加!

主讲人:Klavs Hansen教授

题目:Single photon hot electron ionization of fullerenes

时间:9月26日上午9:40

地点:格致楼3016

联系人:罗洪刚/程晨

报告摘要:

The ionization of neutral molecules and electron detachment of anions can proceed in thermal processes, analogously to the bulk thermionic emission. The process involves thermal excitations of valence electrons to a vacuum state by coupling of vibrational and electronic degrees of freedom. Such processes will occur on time scales beyond the coupling time, which is typically on the order of a picosecond. Electronic excitations that occur on shorter time scales will cause the excitation to reside in the electronic states. Such transiently excited electronic system may also emit thermal electrons. The effective temperatures in these hot electron emissions is on the order of 1 eV. Hot electron emission has been observed from several large molecules and clusters, including the fullerenes, PAH molecules and metal clusters after multiphoton excitation with near-infrared and UV photons in femtosecond laser pulses.

Recently hot electron emission was been also observed in fullerenes after the absorption of a single, high energy photon. I will present results from these experiments and discuss the implications for the electron-electron relaxation mechanism and the observation of the effect in other systems.

In analogy with thermal equilibrium, the out-of-equilibrium critical phenomena is far less understood. We explore the non-equilibrium steady-state of a transverse magnetic field Ising chain coupled at its ends to magnetic thermal reservoirs. We generalize the phase diagram to non-equilibrium conditions obtained by applying a magnetization bias to the reservoirs. Upon increasing the bias we observe a novel critical phenomena not possible at equilibrium. Moreover, for steady-states with a non-vanishing conductance, the entanglement entropy at the zero temperature was found to have logarithmic corrections that differ from the well-known equilibrium case.

[1] Klavs Hansen, et al., Single photon thermal ionisation of C60, Phys. Rev. Lett. 2017, 118, 103001.

个人简介:

Klavs Hansen博士毕业于尼尔斯波尔研究所,目前是天津大学理学院教授、鲁汶大学客座教授,于2016年荣获天津市荣誉称号。现主要研究方向为气相纳米尺度粒子的量子效应和热效应,已发表论文151篇,累计被引3900余次。