1
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Girotto N, Novko D. Dynamical Phonons Following Electron Relaxation Stages in Photoexcited Graphene. J Phys Chem Lett 2023; 14:8709-8716. [PMID: 37735110 DOI: 10.1021/acs.jpclett.3c01905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
Ultrafast electron-phonon relaxation dynamics in graphene hides many distinct phenomena, such as hot phonon generation, dynamical Kohn anomalies, and phonon decoupling, yet it still remains largely unexplored. Here, we unravel intricate mechanisms governing the vibrational relaxation and phonon dressing in graphene at a highly nonequilibrium state by means of first-principles techniques. We calculate dynamical phonon spectral functions and momentum-resolved line widths for various stages of electron relaxation and find photoinduced phonon hardening, overall increase of relaxation rate and nonadiabaticity, as well as phonon gain. Namely, the initial stage of photoexcitation is found to be governed by strong phonon anomalies of finite-momentum optical modes along with incoherent phonon production. The population inversion state, on the other hand, allows the production of coherent and strongly coupled phonon modes. Our research provides vital insights into the electron-phonon coupling phenomena in graphene and serves as a foundation for exploring nonequilibrium phonon dressing in materials where ordered states and phase transitions can be induced by photoexcitation.
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Affiliation(s)
- Nina Girotto
- Centre for Advanced Laser Techniques, Institute of Physics, 10000 Zagreb, Croatia
| | - Dino Novko
- Centre for Advanced Laser Techniques, Institute of Physics, 10000 Zagreb, Croatia
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2
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Prasad N, Burg GW, Watanabe K, Taniguchi T, Register LF, Tutuc E. Quantum Lifetime Spectroscopy and Magnetotunneling in Double Bilayer Graphene Heterostructures. PHYSICAL REVIEW LETTERS 2021; 127:117701. [PMID: 34558942 DOI: 10.1103/physrevlett.127.117701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/31/2021] [Indexed: 06/13/2023]
Abstract
We describe a tunneling spectroscopy technique in a double bilayer graphene heterostructure where momentum-conserving tunneling between different energy bands serves as an energy filter for the tunneling carriers, and allows a measurement of the quasiparticle state broadening at well-defined energies. The broadening increases linearly with the excited state energy with respect to the Fermi level and is weakly dependent on temperature. In-plane magnetotunneling reveals a high degree of rotational alignment between the graphene bilayers, and an absence of momentum randomizing processes.
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Affiliation(s)
- Nitin Prasad
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
| | - G William Burg
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Leonard F Register
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Emanuel Tutuc
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
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3
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Liu G, Bao X, Dong W, Wei Q, Mu H, Zhu W, Wang B, Li J, Shabbir B, Huang Y, Xing G, Yu J, Gao P, Shao H, Li X, Bao Q. Two-Dimensional Bi 2Sr 2CaCu 2O 8+δ Nanosheets for Ultrafast Photonics and Optoelectronics. ACS NANO 2021; 15:8919-8929. [PMID: 33969996 DOI: 10.1021/acsnano.1c01567] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two-dimensional (2D) Bi2Sr2CaCu2O8+δ (BSCCO) is a emerming class of 2D materials with high-temperature superconductivity for which their electronic transport properties have been intensively studied. However, the optical properties, especially nonlinear optical response and the photonic and optoelectronic applications of normal state 2D Bi2Sr2CaCu2O8+δ (Bi-2212), have been largely unexplored. Here, the linear and nonlinear optical properties of mechanically exfoliated Bi-2212 thin flakes are systematically investigated. 2D Bi-2212 shows a profound plasmon absorption in near-infrared wavelength range with ultrafast carrier dynamics as well as tunable nonlinear absorption depending on the thickness. We demonstrated that 2D Bi-2212 can be applied not only as an effective mode-locker for ultrashort pulse generation but also as an active medium for infrared light detection due to its plasmon absorption. Our results may trigger follow up studies on the optical properties of 2D BSCCO and demonstrate potential opportunities for photonic and optoelectronic applications.
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Affiliation(s)
- Guanyu Liu
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Xiaozhi Bao
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau SAR 999078, China
| | - Weikang Dong
- International Center for Quantum Materials, and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Qi Wei
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau SAR 999078, China
| | - Haoran Mu
- Department of Materials Science and Engineering, and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria 3800, Australia
| | - Wenguo Zhu
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou 510632, China
| | - Bingzhe Wang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau SAR 999078, China
| | - Jianding Li
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau SAR 999078, China
| | - Babar Shabbir
- Department of Materials Science and Engineering, and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria 3800, Australia
| | - Yuan Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Guichuan Xing
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau SAR 999078, China
| | - Jianhui Yu
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou 510632, China
| | - Peng Gao
- International Center for Quantum Materials, and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Huaiyu Shao
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau SAR 999078, China
| | - Xiangping Li
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Qiaoliang Bao
- Department of Materials Science and Engineering, and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria 3800, Australia
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4
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Chiu CW, Chung YL, Yang CH, Liu CT, Lin CY. Coulomb decay rates in monolayer doped graphene. RSC Adv 2020; 10:2337-2346. [PMID: 35494571 PMCID: PMC9048988 DOI: 10.1039/c9ra05953a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/16/2019] [Indexed: 11/21/2022] Open
Abstract
Excited conduction electrons, conduction holes, and valence holes in monolayer electron-doped graphene exhibit unusual Coulomb decay rates.
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Affiliation(s)
- Chih-Wei Chiu
- Department of Physics
- National Kaohsiung Normal University
- Kaohsiung 824
- Taiwan
| | - Yue-Lin Chung
- Department of Physics
- National Kaohsiung Normal University
- Kaohsiung 824
- Taiwan
| | - Cheng-Hsueh Yang
- Department of Physics
- National Cheng Kung University
- Tainan 701
- Taiwan
| | - Chang-Ting Liu
- Department of Physics
- National Kaohsiung Normal University
- Kaohsiung 824
- Taiwan
| | - Chiun-Yan Lin
- Department of Physics
- National Cheng Kung University
- Tainan 701
- Taiwan
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5
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Na MX, Mills AK, Boschini F, Michiardi M, Nosarzewski B, Day RP, Razzoli E, Sheyerman A, Schneider M, Levy G, Zhdanovich S, Devereaux TP, Kemper AF, Jones DJ, Damascelli A. Direct determination of mode-projected electron-phonon coupling in the time domain. Science 2019; 366:1231-1236. [DOI: 10.1126/science.aaw1662] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 11/05/2019] [Indexed: 11/02/2022]
Abstract
Ultrafast spectroscopies have become an important tool for elucidating the microscopic description and dynamical properties of quantum materials. In particular, by tracking the dynamics of nonthermal electrons, a material’s dominant scattering processes can be revealed. Here, we present a method for extracting the electron-phonon coupling strength in the time domain, using time- and angle-resolved photoemission spectroscopy (TR-ARPES). This method is demonstrated in graphite, where we investigate the dynamics of photoinjected electrons at the K¯ point, detecting quantized energy-loss processes that correspond to the emission of strongly coupled optical phonons. We show that the observed characteristic time scale for spectral weight transfer mediated by phonon-scattering processes allows for the direct quantitative extraction of electron-phonon matrix elements for specific modes.
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Affiliation(s)
- M. X. Na
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - A. K. Mills
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - F. Boschini
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - M. Michiardi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - B. Nosarzewski
- Department of Materials Science and Engineering, Stanford Institute for Materials and Energy Sciences, Stanford, CA 94305, USA
| | - R. P. Day
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - E. Razzoli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - A. Sheyerman
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - M. Schneider
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - G. Levy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - S. Zhdanovich
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - T. P. Devereaux
- Department of Materials Science and Engineering, Stanford Institute for Materials and Energy Sciences, Stanford, CA 94305, USA
| | - A. F. Kemper
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - D. J. Jones
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - A. Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
- Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
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6
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Yin LJ, Shi LJ, Li SY, Zhang Y, Guo ZH, He L. High-Magnetic-Field Tunneling Spectra of ABC-Stacked Trilayer Graphene on Graphite. PHYSICAL REVIEW LETTERS 2019; 122:146802. [PMID: 31050464 DOI: 10.1103/physrevlett.122.146802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Indexed: 06/09/2023]
Abstract
ABC-stacked trilayer graphene (TLG) was predicted to exhibit novel many-body phenomena due to the existence of almost dispersionless flat bands near the charge neutrality point. Here, using high-magnetic-field scanning tunneling microscopy, we present Landau Level (LL) spectroscopy measurements of high-quality ABC-stacked TLG on graphite. We observe an approximately linear magnetic-field scaling of valley splitting and spin splitting in the ABC-stacked TLG. Our experiment indicates that the spin splitting decreases dramatically with increasing the LL index. When the lowest LL is partially filled, we find an obvious enhancement of the spin splitting, attributing to strong many-body effects. Moreover, we observe linear energy scaling of the inverse lifetime of quasiparticles, providing an additional evidence for the strong electron-electron interactions in the ABC-stacked TLG. These results imply that interesting broken-symmetry states and novel electron correlated effects could emerge in the ABC-stacked TLG in the presence of high magnetic fields.
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Affiliation(s)
- Long-Jing Yin
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing, 100875, China
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Li-Juan Shi
- Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Si-Yu Li
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Yu Zhang
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Zi-Han Guo
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Lin He
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing, 100875, China
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7
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Tan S, Liu L, Dai Y, Ren J, Zhao J, Petek H. Ultrafast Plasmon-Enhanced Hot Electron Generation at Ag Nanocluster/Graphite Heterojunctions. J Am Chem Soc 2017; 139:6160-6168. [DOI: 10.1021/jacs.7b01079] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Shijing Tan
- Department
of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Liming Liu
- ICQD/Hefei
National Laboratory for Physical Sciences at Microscale, and Key Laboratory
of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences,
and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yanan Dai
- Department
of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jindong Ren
- Department
of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jin Zhao
- Department
of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- ICQD/Hefei
National Laboratory for Physical Sciences at Microscale, and Key Laboratory
of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences,
and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hrvoje Petek
- Department
of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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8
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Ishida Y, Otsu T, Ozawa A, Yaji K, Tani S, Shin S, Kobayashi Y. High repetition pump-and-probe photoemission spectroscopy based on a compact fiber laser system. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:123902. [PMID: 28040935 DOI: 10.1063/1.4969053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The paper describes a time-resolved photoemission (TRPES) apparatus equipped with a Yb-doped fiber laser system delivering 1.2-eV pump and 5.9-eV probe pulses at the repetition rate of 95 MHz. Time and energy resolutions are 11.3 meV and ∼310 fs, respectively, the latter is estimated by performing TRPES on a highly oriented pyrolytic graphite (HOPG). The high repetition rate is suited for achieving high signal-to-noise ratio in TRPES spectra, thereby facilitating investigations of ultrafast electronic dynamics in the low pump fluence (p) region. TRPES of polycrystalline bismuth (Bi) at p as low as 30 nJ/mm2 is demonstrated. The laser source is compact and is docked to an existing TRPES apparatus based on a 250-kHz Ti:sapphire laser system. The 95-MHz system is less prone to space-charge broadening effects compared to the 250-kHz system, which we explicitly show in a systematic probe-power dependency of the Fermi cutoff of polycrystalline gold. We also describe that the TRPES response of an oriented Bi(111)/HOPG sample is useful for fine-tuning the spatial overlap of the pump and probe beams even when p is as low as 30 nJ/mm2.
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Affiliation(s)
- Y Ishida
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - T Otsu
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - A Ozawa
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - K Yaji
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - S Tani
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - S Shin
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - Y Kobayashi
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
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9
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Microscopic origins of the terahertz carrier relaxation and cooling dynamics in graphene. Nat Commun 2016; 7:11617. [PMID: 27221060 PMCID: PMC4894949 DOI: 10.1038/ncomms11617] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/14/2016] [Indexed: 11/08/2022] Open
Abstract
The ultrafast dynamics of hot carriers in graphene are key to both understanding of fundamental carrier–carrier interactions and carrier–phonon relaxation processes in two-dimensional materials, and understanding of the physics underlying novel high-speed electronic and optoelectronic devices. Many recent experiments on hot carriers using terahertz spectroscopy and related techniques have interpreted the variety of observed signals within phenomenological frameworks, and sometimes invoke extrinsic effects such as disorder. Here, we present an integrated experimental and theoretical programme, using ultrafast time-resolved terahertz spectroscopy combined with microscopic modelling, to systematically investigate the hot-carrier dynamics in a wide array of graphene samples having varying amounts of disorder and with either high or low doping levels. The theory reproduces the observed dynamics quantitatively without the need to invoke any fitting parameters, phenomenological models or extrinsic effects such as disorder. We demonstrate that the dynamics are dominated by the combined effect of efficient carrier–carrier scattering, which maintains a thermalized carrier distribution, and carrier–optical–phonon scattering, which removes energy from the carrier liquid. Design of high-speed graphene-based devices relies on understanding of its ultrafast carrier dynamics. Here, the authors combine time-resolved terahertz spectroscopy and microscopic modelling to unveil the interplay between the scattering mechanisms dominating the ultrafast relaxation pathways in graphene.
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10
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Ishida Y, Togashi T, Yamamoto K, Tanaka M, Taniuchi T, Kiss T, Nakajima M, Suemoto T, Shin S. Non-thermal hot electrons ultrafastly generating hot optical phonons in graphite. Sci Rep 2011; 1:64. [PMID: 22355583 PMCID: PMC3216551 DOI: 10.1038/srep00064] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 07/25/2011] [Indexed: 11/28/2022] Open
Abstract
Investigation of the non-equilibrium dynamics after an impulsive impact provides insights into couplings among various excitations. A two-temperature model (TTM) is often a starting point to understand the coupled dynamics of electrons and lattice vibrations: the optical pulse primarily raises the electronic temperature T(el) while leaving the lattice temperature T(l) low; subsequently the hot electrons heat up the lattice until T(el) = T(l) is reached. This temporal hierarchy owes to the assumption that the electron-electron scattering rate is much larger than the electron-phonon scattering rate. We report herein that the TTM scheme is seriously invalidated in semimetal graphite. Time-resolved photoemission spectroscopy (TrPES) of graphite reveals that fingerprints of coupled optical phonons (COPs) occur from the initial moments where T(el) is still not definable. Our study shows that ultrafast-and-efficient phonon generations occur beyond the TTM scheme, presumably associated to the long duration of the non-thermal electrons in graphite.
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Affiliation(s)
- Y Ishida
- ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
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11
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Abstract
The Landau-Fermi liquid picture for quasiparticles assumes that charge carriers are dressed by many-body interactions, forming one of the fundamental theories of solids. Whether this picture still holds for a semimetal such as graphene at the neutrality point, i.e., when the chemical potential coincides with the Dirac point energy, is one of the long-standing puzzles in this field. Here we present such a study in quasi-freestanding graphene by using high-resolution angle-resolved photoemission spectroscopy. We see the electron-electron and electron-phonon interactions go through substantial changes when the semimetallic regime is approached, including renormalizations due to strong electron-electron interactions with similarities to marginal Fermi liquid behavior. These findings set a new benchmark in our understanding of many-body physics in graphene and a variety of novel materials with Dirac fermions.
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12
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Shang J, Yu T, Lin J, Gurzadyan GG. Ultrafast electron-optical phonon scattering and quasiparticle lifetime in CVD-grown graphene. ACS NANO 2011; 5:3278-3283. [PMID: 21391596 DOI: 10.1021/nn200419z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Ultrafast quasiparticle dynamics in graphene grown by chemical vapor deposition (CVD) has been studied by UV pump/white-light probe spectroscopy. Transient differential transmission spectra of monolayer graphene are observed in the visible probe range (400-650 nm). Kinetics of the quasiparticle (i.e., low-energy single-particle excitation with renormalized energy due to electron-electron Coulomb, electron-optical phonon (e-op), and optical phonon-acoustic phonon (op-ap) interactions) was monitored with 50 fs resolution. Extending the probe range to near-infrared, we find the evolution of quasiparticle relaxation channels from monoexponential e-op scattering to double exponential decay due to e-op and op-ap scattering. Moreover, quasiparticle lifetimes of mono- and randomly stacked graphene films are obtained for the probe photon energies continuously from 1.9 to 2.3 eV. Dependence of quasiparticle decay rate on the probe energy is linear for 10-layer stacked graphene films. This is due to the dominant e-op intervalley scattering and the linear density of states in the probed electronic band. A dimensionless coupling constant W is derived, which characterizes the scattering strength of quasiparticles by lattice points in graphene.
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Affiliation(s)
- Jingzhi Shang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
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13
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14
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Frigge R, Hoger T, Siemer B, Witte H, Silies M, Zacharias H, Olsen T, Schiøtz J. Site specificity in femtosecond laser desorption of neutral H atoms from graphite(0001). PHYSICAL REVIEW LETTERS 2010; 104:256102. [PMID: 20867400 DOI: 10.1103/physrevlett.104.256102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Indexed: 05/29/2023]
Abstract
Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400 ms^{-1} for H and D atoms are associated with the desorption out of the highest vibrational state of a barrierless potential.
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Affiliation(s)
- R Frigge
- Physikalisches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität, 48149 Münster, Germany.
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15
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Castro EV, Novoselov KS, Morozov SV, Peres NMR, Lopes dos Santos JMB, Nilsson J, Guinea F, Geim AK, Castro Neto AH. Electronic properties of a biased graphene bilayer. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:175503. [PMID: 21393670 DOI: 10.1103/revmodphys.81.109] [Citation(s) in RCA: 5762] [Impact Index Per Article: 411.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system-a biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its four-band and two-band continuum approximations, and the four-band model is shown to always be a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, made out of either SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point for understanding the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, such as the second-nearest-neighbour hopping energies t' (in-plane) and γ(4) (inter-layer), and the on-site energy Δ.
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Affiliation(s)
- Eduardo V Castro
- CFP and Departamento de Física, Faculdade de Ciências Universidade do Porto, P-4169-007 Porto, Portugal
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16
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Kim KS, Yeom HW. Giant kink in electron dispersion of strongly coupled lead nanowires. NANO LETTERS 2009; 9:1916-1920. [PMID: 19331422 DOI: 10.1021/nl900052s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Our photoelectron spectroscopy study shows a giant kink in the electron dispersion, a sign of high-energy manybody interactions of electrons, in a well-ordered Pb nanowire array self-assembled on a silicon substrate. We show that the unique electronic band structure due to the strong lateral coupling and the atomic structure of the nanowires drives an enhanced manybody interaction for kinked electron dispersion. The major giant kink mechanisms discussed previously, the magnetic and plasmonic excitations, are not relevant in the present system, supporting the recent kink theory based purely on electron-electron correlation. This suggests that tailored electronic band structures in nano array systems can provide unprecedented ways to study manybody interactions of electrons.
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Affiliation(s)
- Keun Su Kim
- Institute of Physics and Applied Physics and Center for Atomic Wires and Layers, Yonsei University, Seoul 120-749, Korea
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17
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Breusing M, Ropers C, Elsaesser T. Ultrafast carrier dynamics in graphite. PHYSICAL REVIEW LETTERS 2009; 102:086809. [PMID: 19257774 DOI: 10.1103/physrevlett.102.086809] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Indexed: 05/22/2023]
Abstract
Optical pump-probe spectroscopy with 7-fs pump pulses and a probe spectrum wider than 0.7 eV reveals the ultrafast carrier dynamics in freestanding thin graphite films. We discern for the first time a rapid intraband carrier equilibration within 30 fs, leaving the system with separated electron and hole chemical potentials. Phonon-mediated intraband cooling of electrons and holes occurs on a 100 fs time scale. The kinetics are in agreement with simulations based on Boltzmann equations.
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Affiliation(s)
- Markus Breusing
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany
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18
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Newson RW, Ménard JM, Sames C, Betz M, van Driel HM. Coherently controlled ballistic charge currents injected in single-walled carbon nanotubes and graphite. NANO LETTERS 2008; 8:1586-1589. [PMID: 18479170 DOI: 10.1021/nl073305l] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ballistic electrical currents are optically injected into aligned single-walled carbon nanotubes and bulk graphite at 300 K via quantum interference between single and two photon absorption of phase-related 700 and 1400 nm, 150 fs pulses. The transient currents are detected via the emitted terahertz radiation. Optical phase and power dependence are consistent with the quantum interference optical process. Under similar excitation conditions, the peak current for a forest of nanotubes, with a diameter distribution of approximately 2.5 +/- 1.5 nm, is 9 +/- 1 times larger than that in graphite. At peak focused intensities of 10 GW cm(-2) (1400 nm) and 0.15 GW cm(-2) (700 nm), the peak current is approximately 1 nA per nanotube. The peak current for pump light polarized along the tubes is approximately 3.5 times higher than that for light polarized perpendicular to the tubes.
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Affiliation(s)
- Ryan W Newson
- Department of Physics and Institute for Optical Sciences, University of Toronto, Toronto, ON, Canada
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19
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Lee JD, Han SW, Inoue J. Sharp contrasts in low-energy quasiparticle dynamics of graphite between Brillouin zone K and H points. PHYSICAL REVIEW LETTERS 2008; 100:216801. [PMID: 18518624 DOI: 10.1103/physrevlett.100.216801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Indexed: 05/26/2023]
Abstract
The low-energy quasiparticle (QP) dynamics of graphite are governed by a coupling with the E(2g) longitudinal optical phonon of omega(LO) approximately 200 meV, which is found to dramatically depend on the electronic band dispersion epsilon(k). A discontinuity of the QP linewidth develops near omega(LO) for a linear band with a quadratic band top [near the Brillouin zone (BZ) K point], while it disappears for a pure linear band (near the BZ H point). It is also found that the effective electron-phonon coupling near the K point is stronger than near the H point by more than 50%. This finding makes possible a consistent understanding of recent angle-resolved photoemission observations near the K point.
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Affiliation(s)
- J D Lee
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
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20
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Leem CS, Kim BJ, Kim C, Park SR, Ohta T, Bostwick A, Rotenberg E, Kim HD, Kim MK, Choi HJ, Kim C. Effect of linear density of states on the quasiparticle dynamics and small electron-phonon coupling in graphite. PHYSICAL REVIEW LETTERS 2008; 100:016802. [PMID: 18232802 DOI: 10.1103/physrevlett.100.016802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Indexed: 05/25/2023]
Abstract
We obtained the spectral function of very high quality natural graphite single crystals using angle-resolved photoelectron spectroscopy. A clear separation of nonbonding and bonding bands and asymmetric lineshape are observed. The asymmetric line shapes are well accounted for by the finite photoelectron escape depth and the band structure. The extracted width of the spectral function (inverse of the photohole life time) near the K point is, beyond the maximum phonon energy, approximately proportional to the energy as expected from the linear density of states near the Fermi energy. The upper bound for the electron-phonon coupling constant is about 0.2, a much smaller value than the previously reported one.
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Affiliation(s)
- C S Leem
- Institute of Physics and Applied Physics, Yonsei University, Seoul, Korea
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21
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Sugawara K, Sato T, Souma S, Takahashi T, Suematsu H. Anomalous quasiparticle lifetime and strong electron-phonon coupling in graphite. PHYSICAL REVIEW LETTERS 2007; 98:036801. [PMID: 17358708 DOI: 10.1103/physrevlett.98.036801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Indexed: 05/14/2023]
Abstract
We have performed ultrahigh-resolution angle-resolved photoemission spectroscopy on high-quality single crystals of graphite to elucidate the character of low-energy excitations. We found evidence for a well-defined quasiparticle (QP) peak in the close vicinity of the Fermi level comparable to the nodal QP in high-T(c) cuprates, together with the mass renormalization of the band at an extremely narrow momentum region around the K(H) point. Analysis of the QP lifetime demonstrates the presence of strong electron-phonon coupling and linear energy dependence of the QP scattering rate indicative of a marked deviation from the conventional Fermi-liquid theory.
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Affiliation(s)
- K Sugawara
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
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22
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23
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Vozmediano MAH, López-Sancho MP, Guinea F. Confinement of electrons in layered metals. PHYSICAL REVIEW LETTERS 2002; 89:166401. [PMID: 12398739 DOI: 10.1103/physrevlett.89.166401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2001] [Indexed: 05/24/2023]
Abstract
We analyze the out of plane hopping in models of layered systems where the in-plane properties deviate from Landau's theory of a Fermi liquid. We show that the hopping term acquires a nontrivial energy dependence, due to the coupling to in-plane excitations, and the resulting state, at low temperatures, can be either conducting or insulating in the third direction. The latter is always the case if the Fermi level lies close to a saddle point in the dispersion relation.
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Affiliation(s)
- M A H Vozmediano
- Departamento de Matemáticas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganés, Spain
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24
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Moos G, Gahl C, Fasel R, Wolf M, Hertel T. Anisotropy of quasiparticle lifetimes and the role of disorder in graphite from ultrafast time-resolved photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2001; 87:267402. [PMID: 11800855 DOI: 10.1103/physrevlett.87.267402] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2001] [Indexed: 05/23/2023]
Abstract
Femtosecond time-resolved photoemission of photoexcited electrons in highly oriented pyrolytic graphite (HOPG) provides strong evidence for anisotropies of quasiparticle (QP) lifetimes. Indicative of such anisotropies is a pronounced anomaly in the energy dependence of QP lifetimes between 1.1 and 1.5 eV--the vicinity of a saddle point in the graphite band structure. This is supported by recent ab initio calculations and a comparison with experiments on defect-enriched HOPG which reveal that disorder, e.g., defects or phonons, increases electron energy relaxation rates.
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Affiliation(s)
- G Moos
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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25
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Spataru CD, Cazalilla MA, Rubio A, Benedict LX, Echenique PM, Louie SG. Anomalous quasiparticle lifetime in graphite: band structure effects. PHYSICAL REVIEW LETTERS 2001; 87:246405. [PMID: 11736524 DOI: 10.1103/physrevlett.87.246405] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2001] [Indexed: 05/23/2023]
Abstract
We report ab initio calculations of quasiparticle lifetimes in graphite, as determined from the imaginary part of the self-energy operator within the GW approximation. The inverse lifetime in the energy range from 0.5 to 3.5 eV above the Fermi level presents significant deviations from the quadratic behavior naively expected from Fermi liquid theory. The deviations are explained in terms of the unique features of the band structure of this material. We also discuss the experimental results from different groups and make some predictions for future experiments.
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Affiliation(s)
- C D Spataru
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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26
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Khveshchenko DV. Ghost excitonic insulator transition in layered graphite. PHYSICAL REVIEW LETTERS 2001; 87:246802. [PMID: 11736528 DOI: 10.1103/physrevlett.87.246802] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2001] [Indexed: 05/23/2023]
Abstract
Some unusual properties of layered graphite, including a linear energy dependence of the quasiparticle damping and weak ferromagnetism at low doping, are explained as a result of the proximity of a single graphene sheet to the excitonic insulator phase which can be further stabilized in a doped system of many layers stacked in the staggered ( ABAB...) configuration.
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Affiliation(s)
- D V Khveshchenko
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Farztdinov VM, Kovalenko SA, Lozovik YE, Lisin DV, Matveets YA, Zhuravleva TS, Geskin VM, Zemtsov LM, Kozlov VV, Marowsky G. Ultrafast Optical Response of Carbon Films. J Phys Chem B 1999. [DOI: 10.1021/jp992363v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Gerd Marowsky
- Laser Laboratorium Göttingen e.V., D-37077 Göttingen, Germany
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30
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Xu S, Miller C, Diol S, Gao Y, Mantell D, Mason M, Muenter A, Sharp L, Parkinson B, Miller R. Ultrafast electron dynamics in two dimensional layered systems: two-photon photoemission studies of SnS2. Chem Phys Lett 1997. [DOI: 10.1016/s0009-2614(97)88011-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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31
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Hellsing B, Chakarov DV, Österlund L, Zhdanov VP, Kasemo B. Photoinduced desorption of potassium atoms from a two dimensional overlayer on graphite. J Chem Phys 1997. [DOI: 10.1063/1.473177] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Zheng L. Inelastic lifetimes of confined two-component electron systems in semiconductor quantum-wire and quantum-well structures. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:13908-13914. [PMID: 9985308 DOI: 10.1103/physrevb.54.13908] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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33
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Ahuja R, Brühwiler PA, Wills JM, Johansson B, Mårtensson N, Eriksson O. Theoretical and experimental study of the graphite 1s x-ray absorption edges. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:14396-14404. [PMID: 9985445 DOI: 10.1103/physrevb.54.14396] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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34
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González J, Guinea F, Vozmediano MA. Unconventional Quasiparticle Lifetime in Graphite. PHYSICAL REVIEW LETTERS 1996; 77:3589-3592. [PMID: 10062258 DOI: 10.1103/physrevlett.77.3589] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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35
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Xu S, Cao J, Miller CC, Mantell DA, Miller RJ, Gao Y. Xu et al. Reply. PHYSICAL REVIEW LETTERS 1996; 77:1411. [PMID: 10063070 DOI: 10.1103/physrevlett.77.1411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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36
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Zheng L. Comment on "Energy Dependence of Electron Lifetime in Graphite Observed with Femtosecond Photoemission Spectroscopy". PHYSICAL REVIEW LETTERS 1996; 77:1410. [PMID: 10063069 DOI: 10.1103/physrevlett.77.1410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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