Hrvoje Petek

Department of Physics and Astronomy, University of Pittsburgh
Ph.D., Chemistry, University of California Berkeley, 1985
Summary:

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 <1 fs, <20 nm, <100 meV carrier energy resolution. This technique will be applied to fundamental studies of carrier dynamics in individual nanostructures and coupled nanocomposite systems, in order to understand the fundamental physics of hot carriers in low dimensional systems and to develop advanced device concepts. Atomic manipulation with light Electronic excitation of clean or adsorbate covered metal surfaces can impulsively turn–on large mechanical forces that lead to mass transport parallel or perpendicular to the surface. When such forces are harnessed properly, they can be used for atomic manipulation or even atomic switching. Although there are now several examples of atomic manipulation with STM techniques, much less is known about how equivalent, but much larger scale manipulation could be accomplished with light. The recent observation and demonstration of quantum control of motion of Cs atoms above a Cu(111) surface by our group provides a proof–of–principle for the atomic manipulation of surfaces with light. Such studies are being extended to identify the factors that govern the electronic relaxation of adsorbates on metal surfaces, which can effectively quench the nuclear motion.

Students
Namesort descending Position Email
Ghosh, Atreyie Graduate Student atg33@pitt.edu
James, Namitha Graduate Student naj43@pitt.edu
Lim, Heeseon Postdoctoral Fellow hel58@pitt.edu
Tan, Shijing Adjunct Assistant Professor shijing@pitt.edu
Wang, Zehua Graduate Student zew23@pitt.edu
Wang, Tianyi Graduate Student tiw60@pitt.edu
Wu, Chunchun Graduate Student chw218@pitt.edu
Yang, Sena Postdoctoral Fellow sey29@pitt.edu
Zhou, Zhikang Graduate Student zhz100@pitt.edu

Atreyie Ghosh

Graduate Student

atg33@pitt.edu
3941 O'Hara St, Pittsburgh PA, 15213

Affiliation:

Physics and Astronomy
University of Pittsburgh

Namitha James

Graduate Student

naj43@pitt.edu
Allen G10A Desk #3, Pittsburgh PA, 15213

Affiliation:

Physics
University of Pittsburgh

Heeseon Lim

Postdoctoral Fellow

hel58@pitt.edu
G-01 Allen Hall, Pittsburgh PA, 15213

Affiliation:

Physics
University of Pittsburgh

Shijing Tan

Adjunct Assistant Professor

shijing@pitt.edu
3941 O'Hara Street, Pittsburgh PA, 15260

Affiliation:

Physics
University of Pittsburgh

Zehua Wang

Graduate Student

zew23@pitt.edu
G01 Allen Hall, Pittsburgh PA, 15260

Affiliation:

Physics and Astronomy
University of Pittsburgh

Tianyi Wang

Graduate Student

tiw60@pitt.edu
G-01 Allen Hall, Pittsburgh PA, 15213

Affiliation:

Physics
University of Pittsburgh

Chunchun Wu

Graduate Student

chw218@pitt.edu
G01 Allen Hall, Pittsburgh PA, 15213

Affiliation:

Physics
University of Pittsburgh

Sena Yang

Postdoctoral Fellow

sey29@pitt.edu
G-01 Allen Hall, Pittsburgh PA, 15213

Affiliation:

Physics
University of Pittsburgh

Zhikang Zhou

Graduate Student

zhz100@pitt.edu
3941 O'Hara St, Pittsburgh PA, 15213

Affiliation:

Physics
University of Pittsburgh
Most Cited Publications
  1. Y. Dai, Z. Zhou, A. Ghosh, R. S. K. Mong, A. Kubo, C. –B. Huang, and H. Petek, “Plasmonic topological quasiparticle on the nanometre and femtosecond scales,” Nature 588, 616 (2020).
  2.  M. Reutzel, A. Li, and H. Petek, “Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces,” Phys. Rev. X 9, 011044 (2019).
  3.  M. Dąbrowski, Y. Dai, and H. Petek, “Ultrafast photoemission electron microscopy imaging plasmons in space and time,” Chem. Rev. 120, 6247 (2020).
  4.  M. Feng, J. Zhao, and H. Petek, “Atomlike, Hollow-core-Bound Molecular Orbitals of C60” Science 320, 359 (2008).
  5.  H. Petek and S. Ogawa, “Femtosecond Time-resolved Two-Photon Photoemission Studies of Electron Dynamics in Metals,” Prog. Surf. Sci. 56, 239 (1997).
Recent Publications
  1. "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)
  2. "Plasmonic Spin-Hall Effect in Surface Plasmon Polariton Focusing,"  Y Dai and H PetekACS Photonics (2019)
  3. "Nonlinear Plasmonic Photoelectron Response of Ag (111),"  M Reutzel, A Li, B Gumhalter, and H PetekPhysical Review Letters 123.1 (2019).
  4. "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)
  5. "Coherent two-dimensional multiphoton photoelectron spectroscopy of metal surfaces,"  M Reutzel, A Li, and H PetekPhysical Review X 9.1 (2019)

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