Hrvoje Petek

Last updated
Hrvoje Petek
Born(1958-01-13)January 13, 1958
Zagreb, Croatia
NationalityAmerican, Croatian
Alma mater Massachusetts Institute of Technology (1980, B.S., Chemistry)
University of California, Berkeley (1985, Ph.D., Chemistry)
Known for Ultrafast laser spectroscopy,
Ultrafast microscopy,
Plasmonics,
Two-photon photoelectron spectroscopy
Scientific career
Fields Experimental physics
InstitutionsInstitute for Molecular Science
Hitachi Ltd.
University of Pittsburgh

Hrvoje Petek (born January 13, 1958) is a Croatian-born American physicist and the Richard King Mellon Professor of Physics and Astronomy, [1] at the University of Pittsburgh, where he is also a professor of chemistry. [2]

Contents

Education

Petek received his B.S. degree in chemistry from Massachusetts Institute of Technology in 1980. [3] Subsequently, he obtained his Ph.D. degree in chemistry from the University of California, Berkeley in 1985. [4]

Research and career

Petek has developed coherent photoelectron spectroscopy [5] [6] and microscopy [7] as methods for studying the dephasing and spatial propagation of polarization fields in solid state materials and nanostructure. He is developing methods for multidimensional multiphoton-photoemission spectroscopy. [8] Together with Taketoshi Minato, Yousoo Kim, Maki Kawai, Jin Zhao, Jinlong Yang and Jianguo Hou, Petek discovered a delocalized electronic structure created by oxygen vacancy on titanium dioxide surface. [9] Together with Jin Zhao, Ken Jordan and Ken Onda, Petek also discovered wet electron states, where electrons are partially solvated by water and other protic solvents at molecule vacuum interfaces. [10] Together with Min Feng and Jin Zhao, Petek discovered atom-like superatom states of C60, and similar hollow molecules. [11] Petek's research of metal plasmon excitations with semiconductor substrates, unrevealed the charge injection from optically active plasmonic modes into semiconductor substrates. [12]

Petek is editor-in-chief of Progress in Surface Science [13] and has organized conferences such as the 11th International Symposium of Ultrafast Surface Dynamics, held in Qiandao Lake, China. [14] Petek has been (2015-2019) a member of the National Research and Development Agency Committee for the National Institute for Materials Science and is currently a senior scientific advisor to the Japanese Institute for Molecular Science. [15]

Awards and honors

Related Research Articles

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The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, and solid state and quantum chemistry to draw inferences about the properties of atoms, molecules and solids. The effect has found use in electronic devices specialized for light detection and precisely timed electron emission.

<span class="mw-page-title-main">Photoluminescence</span> Light emission from substances after they absorb photons

Photoluminescence is light emission from any form of matter after the absorption of photons. It is one of many forms of luminescence and is initiated by photoexcitation, hence the prefix photo-. Following excitation, various relaxation processes typically occur in which other photons are re-radiated. Time periods between absorption and emission may vary: ranging from short femtosecond-regime for emission involving free-carrier plasma in inorganic semiconductors up to milliseconds for phosphoresence processes in molecular systems; and under special circumstances delay of emission may even span to minutes or hours.

<span class="mw-page-title-main">Plasmon</span> Quasiparticle of charge oscillations in condensed matter

In physics, a plasmon is a quantum of plasma oscillation. Just as light consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quantization of plasma oscillations, just like phonons are quantizations of mechanical vibrations. Thus, plasmons are collective oscillations of the free electron gas density. For example, at optical frequencies, plasmons can couple with a photon to create another quasiparticle called a plasmon polariton.

<span class="mw-page-title-main">Photoemission spectroscopy</span> Examining a substance by measuring electrons emitted in the photoelectric effect

Photoemission spectroscopy (PES), also known as photoelectron spectroscopy, refers to energy measurement of electrons emitted from solids, gases or liquids by the photoelectric effect, in order to determine the binding energies of electrons in the substance. The term refers to various techniques, depending on whether the ionization energy is provided by X-ray, XUV or UV photons. Regardless of the incident photon beam, however, all photoelectron spectroscopy revolves around the general theme of surface analysis by measuring the ejected electrons.

Photoemission electron microscopy is a type of electron microscopy that utilizes local variations in electron emission to generate image contrast. The excitation is usually produced by ultraviolet light, synchrotron radiation or X-ray sources. PEEM measures the coefficient indirectly by collecting the emitted secondary electrons generated in the electron cascade that follows the creation of the primary core hole in the absorption process. PEEM is a surface sensitive technique because the emitted electrons originate from a shallow layer. In physics, this technique is referred to as PEEM, which goes together naturally with low-energy electron diffraction (LEED), and low-energy electron microscopy (LEEM). In biology, it is called photoelectron microscopy (PEM), which fits with photoelectron spectroscopy (PES), transmission electron microscopy (TEM), and scanning electron microscopy (SEM).

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Photofragment ion imaging or, more generally, Product Imaging is an experimental technique for making measurements of the velocity of product molecules or particles following a chemical reaction or the photodissociation of a parent molecule. The method uses a two-dimensional detector, usually a microchannel plate, to record the arrival positions of state-selected ions created by resonantly enhanced multi-photon ionization (REMPI). The first experiment using photofragment ion imaging was performed by David W Chandler and Paul L Houston in 1987 on the phototodissociation dynamics of methyl iodide (iodomethane, CH3I).

Laser-based angle-resolved photoemission spectroscopy is a form of angle-resolved photoemission spectroscopy that uses a laser as the light source. Photoemission spectroscopy is a powerful and sensitive experimental technique to study surface physics. It is based on the photoelectric effect originally observed by Heinrich Hertz in 1887 and later explained by Albert Einstein in 1905 that when a material is shone by light, the electrons can absorb photons and escape from the material with the kinetic energy: , where is the incident photon energy, the work function of the material. Since the kinetic energy of ejected electrons are highly associated with the internal electronic structure, by analyzing the photoelectron spectroscopy one can realize the fundamental physical and chemical properties of the material, such as the type and arrangement of local bonding, electronic structure and chemical composition.

Photoelectrochemical processes are processes in photoelectrochemistry; they usually involve transforming light into other forms of energy. These processes apply to photochemistry, optically pumped lasers, sensitized solar cells, luminescence, and photochromism.

Marijan Šunjić is a Croatian physicist, university professor, former rector of the University of Zagreb and a diplomat.

LeRoy W. Apker was an American experimental physicist. Along with his colleagues E. A. Taft and Jean Dickey, he studied the photoelectric emission of electrons from semiconductors and discovered the phenomenon of exciton-induced photoemission in potassium iodide. In 1955, he received the Oliver E. Buckley Condensed Matter Prize of the American Physical Society for his work.

Double ionization is a process of formation of doubly charged ions when laser radiation is exerted on neutral atoms or molecules. Double ionization is usually less probable than single-electron ionization. Two types of double ionization are distinguished: sequential and non-sequential.

<span class="mw-page-title-main">Localized surface plasmon</span>

A localized surface plasmon (LSP) is the result of the confinement of a surface plasmon in a nanoparticle of size comparable to or smaller than the wavelength of light used to excite the plasmon. When a small spherical metallic nanoparticle is irradiated by light, the oscillating electric field causes the conduction electrons to oscillate coherently. When the electron cloud is displaced relative to its original position, a restoring force arises from Coulombic attraction between electrons and nuclei. This force causes the electron cloud to oscillate. The oscillation frequency is determined by the density of electrons, the effective electron mass, and the size and shape of the charge distribution. The LSP has two important effects: electric fields near the particle's surface are greatly enhanced and the particle's optical absorption has a maximum at the plasmon resonant frequency. Surface plasmon resonance can also be tuned based on the shape of the nanoparticle. The plasmon frequency can be related to the metal dielectric constant. The enhancement falls off quickly with distance from the surface and, for noble metal nanoparticles, the resonance occurs at visible wavelengths. Localized surface plasmon resonance creates brilliant colors in metal colloidal solutions.

Terahertz spectroscopy detects and controls properties of matter with electromagnetic fields that are in the frequency range between a few hundred gigahertz and several terahertz. In many-body systems, several of the relevant states have an energy difference that matches with the energy of a THz photon. Therefore, THz spectroscopy provides a particularly powerful method in resolving and controlling individual transitions between different many-body states. By doing this, one gains new insights about many-body quantum kinetics and how that can be utilized in developing new technologies that are optimized up to the elementary quantum level.

<span class="mw-page-title-main">Two-photon photoelectron spectroscopy</span>

Time-resolved two-photon photoelectron (2PPE) spectroscopy is a time-resolved spectroscopy technique which is used to study electronic structure and electronic excitations at surfaces. The technique utilizes femtosecond to picosecond laser pulses in order to first photoexcite an electron. After a time delay, the excited electron is photoemitted into a free electron state by a second pulse. The kinetic energy and the emission angle of the photoelectron are measured in an electron energy analyzer. To facilitate investigations on the population and relaxation pathways of the excitation, this measurement is performed at different time delays.

Helen H. Fielding is a Professor of physical chemistry at University College London (UCL). She focuses on ultrafast transient spectroscopy of protein chromophores and molecules. She was the first woman to win the Royal Society of Chemistry (RSC) Harrison-Meldola Memorial Prize (1996) and Marlow Award (2001).

Ultrafast scanning electron microscopy (UFSEM) combines two microscopic modalities, Pump-probe microscopy and Scanning electron microscope, to gather temporal and spatial resolution phenomena. The technique uses ultrashort laser pulses for pump excitation of the material and the sample response will be detected by an Everhart-Thornley detector. Acquiring data depends mainly on formation of images by raster scan mode after pumping with short laser pulse at different delay times. The characterization of the output image will be done through the temporal resolution aspect. Thus, the idea is to exploit the shorter DeBroglie wavelength in respect to the photons which has great impact to increase the resolution about 1 nm. That technique is an up-to-date approach to study the dynamic of charge on material surfaces.

<span class="mw-page-title-main">Majed Chergui</span> Swiss and French physicist

Majed Chergui is a Swiss and French physicist specialized in ultrafast dynamics of light-induced processes. He is a professor at EPFL, head of the Laboratory of Ultrafast Spectroscopy at EPFL's School of Basic Sciences, and founding director of the Lausanne Centre for Ultrafast Science (LACUS).

In physics and chemistry, photoemission orbital tomography is a combined experimental / theoretical approach which reveals information about the spatial distribution of individual molecular orbitals. Experimentally, it uses angle-resolved photoemission spectroscopy (ARPES) to obtain constant binding energy photoemission angular distribution maps, so-called tomograms, to reveal information about the electron probability distribution in molecular orbitals. Theoretically, one rationalizes these tomograms as hemispherical cuts through the molecular orbital in momentum space. This interpretation relies on the assumption of a plane wave final state, i.e., the idea that the outgoing electron can be treated as a free electron, which can be further exploited to reconstruct real-space images of molecular orbitals on a sub-Ångström length scale in two or three dimensions. Presently, POT has been applied to various organic molecules forming well-oriented monolayers on single crystal surfaces or to two-dimensional materials.

Nano Angle-Resolved Photoemission Spectroscopy (Nano-ARPES), is a variant of the experimental technique ARPES. It has the ability to precisely determine the electronic band structure of materials in momentum space with submicron lateral resolution. Due to its demanding experimental setup, this technique is much less extended than ARPES, widely used in condensed matter physics to experimentally determine the electronic properties of a broad range of crystalline materials. Nano-ARPES can access the electronic structure of well-ordered monocrystalline solids with high energy, momentum, and lateral resolution, even if they are nanometric or heterogeneous mesoscopic samples. Nano-ARPES technique is also based on Einstein’s photoelectric effect, being photon-in electron-out spectroscopy, which has converted into an essential tool in studying the electronic structure of nanomaterials, like quantum and low dimensional materials.

References

  1. ↑ "Homepage department of physics & astronomy at University of Pittsburgh".
  2. ↑ "Hrvoje Petek | Department of Chemistry | University of Pittsburgh".
  3. ↑ "Laboratory of Ultrafast Dynamics".
  4. ↑ "Laboratory of Ultrafast Dynamics".
  5. ↑ Ogawa, S.; Nagano, H.; Petek, H.; Heberle, A.P. (17 Feb 1997). "Optical Dephasing in Cu(111) Measured by Interferometric Two-Photon Time-Resolved Photoemission". Phys. Rev. Lett. 78 (7): 1339–1342. Bibcode:1997PhRvL..78.1339O. doi:10.1103/PhysRevLett.78.1339.
  6. ↑ Petek, H.; Ogawa, S. (30 Dec 1997). "Femtosecond time-resolved two-photon photoemission studies of electron dynamics in metals". Progress in Surface Science. 56 (4): 239–310. Bibcode:1997PrSS...56..239P. doi:10.1016/S0079-6816(98)00002-1.
  7. ↑ Dąbrowski, Maciej; Dai, Yanan; Petek, Hrvoje (30 August 2017). "Ultrafast Microscopy: Imaging Light with Photoelectrons on the Nano–Femto Scale". J. Phys. Chem. Lett. 8 (18): 4446–4455. doi:10.1021/acs.jpclett.7b00904. PMID   28853892.
  8. ↑ Reutzel, Marcel; Li, Andi; Petek, Hrvoje (8 March 2019). "Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces". Phys. Rev. X. 9 (1): 011044. arXiv: 1807.09164 . Bibcode:2019PhRvX...9a1044R. doi:10.1103/PhysRevX.9.011044. S2CID   119429960.
  9. ↑ Minato, Taketoshi; Sainoo, Yasuyuki; Kim, Yousoo; Kato, Hiroyuki S.; Aika, Ken-ichi; Kawai, Maki; Zhao, Jin; Petek, Hrvoje; Huang, Tian; He, Wei; Wang, Bing (2009-03-23). "The electronic structure of oxygen atom vacancy and hydroxyl impurity defects on titanium dioxide (110) surface". The Journal of Chemical Physics. 130 (12): 124502. Bibcode:2009JChPh.130l4502M. doi:10.1063/1.3082408. ISSN   0021-9606. PMID   19334846.
  10. ↑ Onda, Ken; Li, Bin; Zhao, Jin; Jordan, Kenneth D.; Yang, Jinglong; Petek, Hrvoje (20 May 2005). "Wet Electrons at the H2O/TiO2(110) Surface". Science. 308 (5725): 1154–1158. Bibcode:2005Sci...308.1154O. doi:10.1126/science.1109366. PMID   15905397. S2CID   46147775.
  11. ↑ Feng, Min; Zhao, Jin; Petek, Hrvoje (18 April 2009). "Atomlike, hollow-core-bound molecular orbitals of C60". Science. 320 (5874): 359–362. Bibcode:2008Sci...320..359F. doi:10.1126/science.1155866. PMID   18420931. S2CID   7839410.
  12. ↑ Tan, Shijing; Argondizzo, Adam; Ren, Jindong; Liu, Liming; Zhao, Jin; Petek, Hrvoje (30 November 2017). "Plasmonic coupling at a metal/semiconductor interface". Nature Photonics. 11 (12): 806–812. Bibcode:2017NaPho..11..806T. doi:10.1038/s41566-017-0049-4. S2CID   125592128.
  13. ↑ "The Editor in Chief of Progress in Surface Science". Progress in Surface Science. Retrieved 2019-05-16.
  14. ↑ "Ultrafast Surface Dynamics 11". usd11.github.io. Retrieved 2019-09-23.
  15. ↑ "Hrvoje Petek, Senior Scientific Advisor". Institute for Molecular Science. Japan. Retrieved 17 May 2019.
  16. ↑ "ACS 2019 national award winners". ACS. Retrieved 2018-09-15.
  17. ↑ "Two Pitt Professors Named American Association for the Advancement of Science Fellows". University of Pittsburgh. Retrieved 2016-12-06.
  18. ↑ "Chancellor's Distinguished Research Award". University of Pittsburgh. Retrieved 2005-03-28.
  19. ↑ "APS Fellow Archive". www.aps.org. Retrieved 2019-09-23.
  20. ↑ "Hrvoje Petek Receives Medal Following Alexander von Humboldt Lecture". Pittsburgh Quantum Institute. Retrieved 2019-09-23.
  21. ↑ "New Energy and Industrial Technology Development Organization". NEDO. Retrieved 2019-05-06.
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