Carrier dynamics in solid–state materials Fundamental electrical, magnetic, and optical properties of solid–state materials are determined by the dynamical response of carriers to internal and external fields. The near–equilibrium properties of carriers in most materials are well understood from classical studies of transport and optical conductivity. However, due to strong interactions of carriers among themselves and with the lattice, studies of nonequlibrium dynamics on femtosecond time scales (10 – 15 s) are just emerging. In our group, a particularly versatile and powerful technique, time–resolved two–photon photoemission (TR–2PP) spectroscopy, has been developed for studying the carrier excitation and relaxation processes in solid–state materials. With this technique we are investigating the quantum mechanical phase and carrier population relaxation times in metals, and for intrinsic and adsorbate induced surface states on metals. Of particular interest are the physical processes that induce e–h pair decoherence, since they impose limits on time scales for quantum control of carriers through the optical phase of the excitation light. The manipulation of the carrier phase with light may lead to applications such as ultrafast (>10 THz) switching and information processing, as well as, atomic manipulation of matter, and therefore, it is of great interest for advanced technologies in the 21st century. Ultrafast microscopy Understanding of the carrier dynamics under quantum confinement is a key to advancing nanoscale science and technology. Although with the existing scanning probe techniques we can potentially study dynamics of individual nanostructures, there is also a clear need for ultrafast imaging microscopic techniques in studies of dynamics in complex systems of nanostructures that could comprise ultrafast electronic or optical device. Photoemission electron microscopy (PEEM) is a well–developed surface science technique for imaging nanostructures on metal and semiconductor surfaces. In combination with femtosecond pump–probe excitation, we intend to develop time–resolved PEEM with potentially
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M. Reutzel, A. Li, and H. Petek, “Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces,” Phys. Rev. X 9, 011044 (2019).
M. Dąbrowski, Y. Dai, and H. Petek, “Ultrafast photoemission electron microscopy imaging plasmons in space and time,” Chem. Rev. 120, 6247 (2020).
M. Feng, J. Zhao, and H. Petek, “Atomlike, Hollow-core-Bound Molecular Orbitals of C60” Science 320, 359 (2008).
H. Petek and S. Ogawa, “Femtosecond Time-resolved Two-Photon Photoemission Studies of Electron Dynamics in Metals,” Prog. Surf. Sci. 56, 239 (1997).
"Realizing nearly-free-electron like conduction band in a molecular film through mediating intermolecular van der Waals interactions, " X Cui, D Han, H Guo, L Zhou, J Qiao, Q Liu, Z Cui, Y Li, C Lin, L Cao, W Ji, H Petek, and M Feng. Nature Communications (2019)
"Plasmonic Spin-Hall Effect in Surface Plasmon Polariton Focusing," Y Dai and H Petek. ACS Photonics (2019)
"Nonlinear Plasmonic Photoelectron Response of Ag (111)," M Reutzel, A Li, B Gumhalter, and H Petek. Physical Review Letters 123.1 (2019).
"Ultrafast asymmetric Rosen-Zener-like coherent phonon responses observed in silicon," Y Watanabe, K Hino, N Maeshima, H Petek, and M Hase. Physical Review B 99.17 (2019)
"Coherent two-dimensional multiphoton photoelectron spectroscopy of metal surfaces," M Reutzel, A Li, and H Petek. Physical Review X 9.1 (2019)