1091-專題演講-1091118-江正天（中研院原分所）
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Time：1091118 (Wed.) 14:20~16:20
Speaker 1：Prof.江正天(CHIANG, Cheng-Tien)
中央研究院原子與分子科學研究所/Institute of Atomic and Molecular Sciences, Academia Sinica
Title：Two-electron photoelectric effect at surfaces
Abstract：Since the discovery of the photoelectric effect, its relevance to the electronic structure of solid surfaces has become a long-standing research topic [1]. As a modern technique to study the general electronic structure of surfaces using the photoelectric effect, angle-resolved photoelectron spectroscopy (ARPES) has successfully revealed the characteristics of quantum materials ranging from graphene, topological insulators, to the two-dimensional semiconducting monolayers of transition metal dichalcogenides [2]. In combination with the recent progress of high-power femtosecond lasers, ultrafast electron dynamics in these materials can be studied by laser-based ARPES in order to reveal the many-body interaction between electrons [3].
In this talk, advanced laser-based photoelectron spectroscopy will be introduced. Moreover, a significant extension of the well-established ARPES toward the direct characterization of electron- electron interaction in solids will be presented. In this so-called double photoemission (DPE) spectroscopy, a pair of electrons is emitted from a solid surface upon the absorption of one single photon [4]. The photoelectron pairs are analyzed by a pair of time-of-flight electron spectrometers in combination with coincidence electronics [5]. As examples, the two-dimensional DPE spectra of Ag(001) and NiO(001) surfaces will be discussed in terms of the specific electron-electron interaction in these materials [6].
[1] H. Hertz, Ann. Phys. 267, 983 (1887); P. Lenard, Ann. Phys. 307, 359 (1900); A. Einstein, Ann. Phys. 22,132(1905); R. A. Millikan, Phys. Rev. 7, 355 (1916). [2] D. Hsieh et al., Nature 460, 1101 (2009); A. Bostwick et al., Nat. Phys. 3, 36 (2007); W. Jin et al., Phys. Rev. Lett. 111, 106801 (2013). [3] P. M. Echenique et al., Surf. Sci. Rep. 52, 219 (2004). [4] C. Gazier and J. R. Prescott, Phys. Lett. 32A, 425 (1970); J. Berakdar, Phys. Rev. 58, 9808 (1998); F. O. Schumann et al., Phys. Rev. Lett. 98, 257604 (2007). [5] M. Huth et al., Appl. Phys. Lett. 104, 061602 (2014). Place：B101, Gongquan Campuses, NTNU
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