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Kurtz F, Dauwe TN, Yalunin SV, Storeck G, Horstmann JG, Böckmann H, Ropers C. Non-thermal phonon dynamics and a quenched exciton condensate probed by surface-sensitive electron diffraction. NATURE MATERIALS 2024; 23:890-897. [PMID: 38688990 PMCID: PMC11230895 DOI: 10.1038/s41563-024-01880-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 03/26/2024] [Indexed: 05/02/2024]
Abstract
Interactions among and between electrons and phonons steer the energy flow in photo-excited materials and govern the emergence of correlated phases. The strength of electron-phonon interactions, decay channels of strongly coupled modes and the evolution of three-dimensional order are revealed by electron or X-ray pulses tracking non-equilibrium structural dynamics. Despite such capabilities, the growing relevance of inherently anisotropic two-dimensional materials and functional heterostructures still calls for techniques with monolayer sensitivity and, specifically, access to out-of-plane phonon polarizations. Here, we resolve non-equilibrium phonon dynamics and quantify the excitonic contribution to the structural order parameter in 1T-TiSe2. To this end, we introduce ultrafast low-energy electron diffuse scattering and trace strongly momentum- and fluence-dependent phonon populations. Mediated by phonon-phonon scattering, a few-picosecond build-up near the zone boundary precedes a far slower generation of zone-centre acoustic modes. These weakly coupled phonons are shown to substantially delay overall equilibration in layered materials. Moreover, we record the surface structural response to a quench of the material's widely investigated exciton condensate, identifying an approximate 30:70 ratio of excitonic versus Peierls contributions to the total lattice distortion in the charge density wave phase. The surface-sensitive approach complements the ultrafast structural toolbox and may further elucidate the impact of phonon scattering in numerous other phenomena within two-dimensional materials, such as the formation of interlayer excitons in twisted bilayers.
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Affiliation(s)
- Felix Kurtz
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Tim N Dauwe
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Sergey V Yalunin
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Gero Storeck
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Jan Gerrit Horstmann
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Hannes Böckmann
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Claus Ropers
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen, Germany.
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2
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Emelianov AV, Pettersson M, Bobrinetskiy II. Ultrafast Laser Processing of 2D Materials: Novel Routes to Advanced Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2402907. [PMID: 38757602 DOI: 10.1002/adma.202402907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/23/2024] [Indexed: 05/18/2024]
Abstract
Ultrafast laser processing has emerged as a versatile technique for modifying materials and introducing novel functionalities. Over the past decade, this method has demonstrated remarkable advantages in the manipulation of 2D layered materials, including synthesis, structuring, functionalization, and local patterning. Unlike continuous-wave and long-pulsed optical methods, ultrafast lasers offer a solution for thermal heating issues. Nonlinear interactions between ultrafast laser pulses and the atomic lattice of 2D materials substantially influence their chemical and physical properties. This paper highlights the transformative role of ultrafast laser pulses in maskless green technology, enabling subtractive, and additive processes that unveil ways for advanced devices. Utilizing the synergetic effect between the energy states within the atomic layers and ultrafast laser irradiation, it is feasible to achieve unprecedented resolutions down to several nanometers. Recent advancements are discussed in functionalization, doping, atomic reconstruction, phase transformation, and 2D and 3D micro- and nanopatterning. A forward-looking perspective on a wide array of applications of 2D materials, along with device fabrication featuring novel physical and chemical properties through direct ultrafast laser writing, is also provided.
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Affiliation(s)
- Aleksei V Emelianov
- Nanoscience Center, Department of Chemistry, University of Jyväskylä, Jyväskylä, FI-40014, Finland
| | - Mika Pettersson
- Nanoscience Center, Department of Chemistry, University of Jyväskylä, Jyväskylä, FI-40014, Finland
| | - Ivan I Bobrinetskiy
- BioSense Institute - Research and Development Institute for Information Technologies in Biosystems, University of Novi Sad, Novi Sad, 21000, Serbia
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3
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Denham P, Yang Y, Guo V, Fisher A, Shen X, Xu T, England RJ, Li RK, Musumeci P. High energy electron diffraction instrument with tunable camera length. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:024302. [PMID: 38532924 PMCID: PMC10965247 DOI: 10.1063/4.0000240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/04/2024] [Indexed: 03/28/2024]
Abstract
Ultrafast electron diffraction (UED) stands as a powerful technique for real-time observation of structural dynamics at the atomic level. In recent years, the use of MeV electrons from radio frequency guns has been widely adopted to take advantage of the relativistic suppression of the space charge effects that otherwise limit the temporal resolution of the technique. Nevertheless, there is not a clear choice for the optimal energy for a UED instrument. Scaling to beam energies higher than a few MeV does pose significant technical challenges, mainly related to the inherent increase in diffraction camera length associated with the smaller Bragg angles. In this study, we report a solution by using a compact post-sample magnetic optical system to magnify the diffraction pattern from a crystal Au sample illuminated by an 8.2 MeV electron beam. Our method employs, as one of the lenses of the optical system, a triplet of compact, high field gradients (>500 T/m), small-gap (3.5 mm) Halbach permanent magnet quadrupoles. Shifting the relative position of the quadrupoles, we demonstrate tuning the magnification by more than a factor of two, a 6× improvement in camera length, and reciprocal space resolution better than 0.1 Å-1 in agreement with beam transport simulations.
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Affiliation(s)
- P. Denham
- Department of Physics and Astronomy, UCLA, Los Angeles, California 90095, USA
| | - Y. Yang
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - V. Guo
- Department of Physics and Astronomy, UCLA, Los Angeles, California 90095, USA
| | - A. Fisher
- Department of Physics and Astronomy, UCLA, Los Angeles, California 90095, USA
| | - X. Shen
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - T. Xu
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R. J. England
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R. K. Li
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - P. Musumeci
- Department of Physics and Astronomy, UCLA, Los Angeles, California 90095, USA
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4
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Ungeheuer A, Bach N, Mir MT, Hassanien AS, Nöding L, Baumert T, Schäfer S, Senftleben A. Coherent acoustic phonons in a coupled hexagonal boron nitride-graphite heterostructure. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:014501. [PMID: 38361662 PMCID: PMC10869168 DOI: 10.1063/4.0000228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 01/19/2024] [Indexed: 02/17/2024]
Abstract
Femtosecond optically excited coherent acoustic phonon modes (CAPs) are investigated in a free-standing van der Waals heterostructure composed of a 20-nm transparent hexagonal boron nitride (hBN) and a 42-nm opaque graphite layer. Employing ultrafast electron diffraction, which allows for the independent evaluation of strain dynamics in the constituent material layers, three different CAP modes are identified within the bilayer stack after the optical excitation of the graphite layer. An analytical model is used to discuss the creation of individual CAP modes. Furthermore, their excitation mechanisms in the heterostructure are inferred from the relative phases of these modes by comparison with a numerical linear-chain model. The results support an ultrafast heat transfer mechanism from graphite to the hBN lattice system, which is important to consider when using this material combination in devices.
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Affiliation(s)
- Arne Ungeheuer
- Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | - Nora Bach
- Institute of Physics, University of Oldenburg, 26129 Oldenburg, Germany
| | - Mashood T. Mir
- Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | | | - Lukas Nöding
- Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | - Thomas Baumert
- Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | - Sascha Schäfer
- Institute of Physics, University of Oldenburg, 26129 Oldenburg, Germany
| | - Arne Senftleben
- Institute of Physics, University of Kassel, 34132 Kassel, Germany
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5
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He X, Yang DS. Nanoscale Energy Transport Dynamics across Nonbonded Solid-Molecule Interfaces and in Molecular Thin Films. J Phys Chem Lett 2023; 14:11457-11464. [PMID: 38085824 DOI: 10.1021/acs.jpclett.3c02673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Thermal conductance across a solid-solid interface requires an atomic- or molecular-level understanding, especially when a system is in a non-equilibrium state and/or consists of nanosized materials with prominent differences in structures, properties, and vibrational behaviors. Here, we report the lattice dynamics of graphite-supported molecular thin films of ethanol, whose layers exhibit in-plane hydrogen-bonded chains and out-of-plane van der Waals stacking with clear structural anisotropy. The direct structure-probing method of ultrafast electron diffraction reveals a surprising temperature difference of more than 400 K at pico- to sub-nanosecond times across the graphite-ethanol interface, yet the temporal behavior signifies a reasonably large thermal boundary conductance. This apparent conflict in a non-equilibrium condition can be resolved by considering the coupling of out-of-plane motions, instead of the commonly used temperature-based model, at transient times for energy transport across the interface separated by van der Waals interactions with mismatched unit sizes and no strong bonds. The importance of spatiotemporally resolved structural dynamics at the atomic or molecular level is emphasized.
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Affiliation(s)
- Xing He
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Ding-Shyue Yang
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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6
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Inami E, Nishioka K, Kanasaki J. Atomic-scale view of the photoinduced structural transition to form sp 3-like bonded order phase in graphite. Sci Rep 2023; 13:21439. [PMID: 38102145 PMCID: PMC10724284 DOI: 10.1038/s41598-023-47389-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/13/2023] [Indexed: 12/17/2023] Open
Abstract
Photoexcitation of solids often induces structural phase transitions between different ordered phases, some of which are unprecedented and thermodynamically inaccessible. The phenomenon, known as photoinduced structural phase transition (PSPT), is of significant interest to the technological progress of advanced materials processing and the fundamental understanding of material physics. Here, we applied scanning tunnelling microscopy (STM) to directly characterise the primary processes of the PSPT in graphite to form a sp3-like carbon nano-phase called diaphite. The primary challenge was to provide microscopic views of the graphite-to-diaphite transition. On an atomic scale, STM imaging of the photoexcited surface revealed the nucleation and proliferation processes of the diaphite phase; these were governed by the formation of sp3-like interlayer bonds. The growth mode of the diaphite phase depends strongly on the photon energy of excitation laser light. Different dynamical pathways were proposed to explain the formation of a sp3-like interlayer bonding. Potential mechanisms for photon-energy-dependent growth were examined based on the experimental and calculated results. The present results provide insight towards realising optical control of sp2-to-sp3 conversions and the organisation of nanoscale structures in graphene-related materials.
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Affiliation(s)
- Eiichi Inami
- School of Systems Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi, 782-8502, Japan.
| | - Keita Nishioka
- Math. and Science Education Research Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa, 921-8501, Japan
| | - Jun'ichi Kanasaki
- Graduate School of Engineering, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan
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7
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Horie R, Hirosue R, Kanasaki J, Kisoda K, Yamamoto I, Azuma J, Takahashi K. Optical film-thinning of graphene epitaxially grown on 4H-SiC(0001): robustness of monolayer-graphene against the photoexcitation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:195401. [PMID: 36854184 DOI: 10.1088/1361-648x/acbffc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
As the properties of graphene films depend on their stacked atomic layers, their thickness should be accurately controlled to improve their specific properties. However, by existing methods, controlling the homogeneity of graphene films at the atomic level remains difficult. In this work, photo-stimulated structural modifications of few-layer graphene epitaxially grown on 4H-SiC(0001) were studied using Raman scattering spectroscopy and core-level photoemission spectroscopy (CLPES). Iterative excitation with laser pulses (800 nm, 100 fs, p-polarized, 250 mJ cm-2) changed the graphene-related two-dimensional (2D) Raman line, which is composed of three components characterized by their different responses upon photoexcitation: two components decaying at fast and slow rates, and a component highly resistant to excitation. CLPES revealed that the observed decay of the 2D line was associated with the elimination of carbon atoms from the graphene layers, finally leaving the robust thin film of single-layer graphene by prolonged excitation. Therefore, this work clearly demonstrates the thickness-dependent structural stability of graphene to optical excitation and opens a promising new method for thinning graphene. An underlying mechanism for the photo-stimulated modifications was also proposed.
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Affiliation(s)
- Ryosuke Horie
- Department of Mechanical Engineering, Osaka Metropolitan University, Sugimoto 3-3-138, Sumiyoshi, Osaka 558-8585, Japan
| | - Ryuichi Hirosue
- Department of Mechanical Engineering, Osaka Metropolitan University, Sugimoto 3-3-138, Sumiyoshi, Osaka 558-8585, Japan
| | - Jun'ichi Kanasaki
- Department of Mechanical Engineering, Osaka Metropolitan University, Sugimoto 3-3-138, Sumiyoshi, Osaka 558-8585, Japan
| | - Kenji Kisoda
- Department of Physics, Wakayama University, Sakaetani 930, Wakayama 640-8441, Japan
| | - Isamu Yamamoto
- Synchrotron Light Application Center, Saga University, Honjo 1, Saga 840-8502, Japan
| | - Junpei Azuma
- Synchrotron Light Application Center, Saga University, Honjo 1, Saga 840-8502, Japan
| | - Kazutoshi Takahashi
- Synchrotron Light Application Center, Saga University, Honjo 1, Saga 840-8502, Japan
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8
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Zheng D, Huang S, Zhu C, Li Z, Zhang Y, Yang D, Tian H, Li J, Yang H, Li J. Enhancement of lattice dynamics by an azimuthal surface plasmon on the femtosecond time scale in multi-walled carbon nanotubes. NANOSCALE 2022; 14:10477-10482. [PMID: 35822870 DOI: 10.1039/d2nr01272c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Plasmon-enhanced light-matter interactions have been widely investigated in the past decades. Here, we report surface plasmon-enhanced structural dynamics in multi-walled carbon nanotubes. The optical polarization dependent dynamic properties of multi-walled carbon nanotubes are investigated using ultrafast transmission electron microscopy. Lattice contractions in the femtosecond time regime are observed upon excitation of the azimuthal plasmon by light polarized perpendicular to the tubular axis. The polarization dependence of the plasmon near field was examined using photon-induced near-field electron microscopy. The lattice changes resulting from the azimuthal plasmon enhance ultrafast alterations in both localized evanescent fields and the collective charge excitation, which play critical roles governing the light-matter interaction. These results suggest that the ultrafast responses of lattice degrees of freedom in nanomaterials could be essential for understanding the mechanism of surface plasmon enhanced effects.
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Affiliation(s)
- Dingguo Zheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Science, Beijing, 100049, China
| | - Siyuan Huang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Science, Beijing, 100049, China
| | - Chunhui Zhu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Zhongwen Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Yongzhao Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Science, Beijing, 100049, China
| | - Dong Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Huanfang Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Jun Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Huaixin Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Science, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Jianqi Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Science, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
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9
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Sun J, Cheng Z, Huang Q, He H, Francisco JS, Du S. Universal Principle for Large-Scale Production of a High-Quality Two-Dimensional Monolayer via Positive Charge-Driven Exfoliation. J Phys Chem Lett 2022; 13:6597-6603. [PMID: 35833746 DOI: 10.1021/acs.jpclett.2c01403] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
On the basis of the intrinsic characteristics of the layered materials, here we report a universal principle for the production of intact monolayers via layer-by-layer exfoliation from their bulk via positive charge doping. At experimental accessible densities (nc) of ∼1014 cm-2, various multilayer crystals, including graphite, hexagonal boron nitride, transition metal dichalcogenides, MXenes, and black phosphorus, can be exfoliated into the corresponding monolayers through ab initio density functional theory stimulations. The carrier critical thresholds for exfoliating are found to be nearly independent of thickness but dependent on surface size. The universality of positive charge-driven exfoliation originates from the common intrinsic characteristics of electronic structures for layered materials. The positively doped charges that preferentially accumulate near the surface induce interlayer repulsion, leading to layer-by-layer exfoliation when repulsion surpasses interlayer van der Waals force. This strategy may open the possibility of producing diverse high-quality two-dimensional monolayers with a small number of defects toward large-scale manufacturing.
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Affiliation(s)
- Junhui Sun
- School of Mechanical Engineering, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Ziwen Cheng
- School of Mechanical Engineering, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China
| | - Qing Huang
- Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Heming He
- School of Mechanical and Electrical Engineering, Guangzhou University, Guangzhou 510006, China
| | - Joseph S Francisco
- Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Shiyu Du
- Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
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10
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Chebl M, He X, Yang DS. Ultrafast Carrier-Coupled Interlayer Contraction, Coherent Intralayer Motions, and Phonon Thermalization Dynamics of Black Phosphorus. NANO LETTERS 2022; 22:5230-5235. [PMID: 35763556 DOI: 10.1021/acs.nanolett.2c01019] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Black phosphorus (bP) exhibits highly anisotropic properties and dynamical behavior that are unique even among two-dimensional and van der Waals (vdW) layered materials. Here, we show that an interlayer lattice contraction and concerted, symmetric intralayer vibrations occur concurrently within few picoseconds following the photoinjection and relaxation of carriers, using ultrafast electron diffraction in the reflection geometry to probe the out-of-plane motions. A strong coupling between the photocarriers and bP's puckered structure, with the alignment of the electronic band structure, is at work for such directional atomic motions without a photoinduced phase transition. Three temporal regimes can be identified for the phonon thermalization dynamics where a quasi-equilibrium without anisotropy is reached in about 50 ps, followed by propagation of coherent acoustic phonons and heat diffusion into the bulk. The early time out-of-plane dynamics reported here have important implications for single- and few-layer bP and other vdW materials with strong electronic-lattice correlations.
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Affiliation(s)
- Mazhar Chebl
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Xing He
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Ding-Shyue Yang
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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11
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Volkov M, Willinger E, Kuznetsov DA, Müller CR, Fedorov A, Baum P. Photo-Switchable Nanoripples in Ti 3C 2Tx MXene. ACS NANO 2021; 15:14071-14079. [PMID: 34464530 DOI: 10.1021/acsnano.1c03635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
MXenes are two-dimensional materials with a rich set of chemical and electromagnetic properties, the latter including saturable absorption and intense surface plasmon resonances. To fully harness the functionality of MXenes for applications in optics, electronics, and sensing, it is important to understand the interaction of light with MXenes on atomic and femtosecond dimensions. Here, we use ultrafast electron diffraction and high-resolution electron microscopy to investigate the laser-induced structural dynamics of Ti3C2Tx nanosheets. We find an exceptionally fast lattice response with an electron-phonon coupling time of 230 fs. Repetitive femtosecond laser excitation transforms Ti3C2Tx through a structural transition into a metamaterial with deeply sub-wavelength nanoripples that are aligned with the laser polarization. By a further laser illumination, the material is reversibly photo-switchable between a flat and rippled morphology. The resulting nanostructured MXene metamaterial with directional nanoripples is expected to exhibit an anisotropic optical and electronic response as well as an enhanced chemical activity that can be switched on and off by light.
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Affiliation(s)
- Mikhail Volkov
- University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany
| | - Elena Willinger
- Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, 8092 Zürich, Switzerland
| | - Denis A Kuznetsov
- Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, 8092 Zürich, Switzerland
| | - Christoph R Müller
- Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, 8092 Zürich, Switzerland
| | - Alexey Fedorov
- Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, 8092 Zürich, Switzerland
| | - Peter Baum
- University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany
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12
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Bach N, Schäfer S. Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2021; 8:035101. [PMID: 34169119 PMCID: PMC8214470 DOI: 10.1063/4.0000079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/21/2021] [Indexed: 06/13/2023]
Abstract
Ultrafast structural probing has greatly enhanced our understanding of the coupling of atomic motion to electronic and phononic degrees-of-freedom in quasi-bulk materials. In bi- and multilayer model systems, additionally, spatially inhomogeneous relaxation channels are accessible, often governed by pronounced interfacial couplings and local excitations in confined geometries. Here, we systematically explore the key dependencies of the low-frequency acoustic phonon spectrum in an elastically mismatched metal/semiconductor bilayer system optically excited by femtosecond laser pulses. We track the spatiotemporal strain wave propagation in the heterostructure employing a discrete numerical linear chain simulation and access acoustic wave reflections and interfacial couplings with a phonon mode description based on a continuum mechanics model. Due to the interplay of elastic properties and mass densities of the two materials, acoustic resonance frequencies of the heterostructure significantly differ from breathing modes in monolayer films. For large acoustic mismatch, the spatial localization of phonon eigenmodes is derived from analytical approximations and can be interpreted as harmonic oscillations in decoupled mechanical resonators.
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Affiliation(s)
- N. Bach
- Institute of Physics, University of Oldenburg, 26129 Oldenburg, Germany
| | - S. Schäfer
- Institute of Physics, University of Oldenburg, 26129 Oldenburg, Germany
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13
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Vialla F, Del Fatti N. Time-Domain Investigations of Coherent Phonons in van der Waals Thin Films. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2543. [PMID: 33348750 PMCID: PMC7766349 DOI: 10.3390/nano10122543] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/11/2020] [Accepted: 12/14/2020] [Indexed: 01/31/2023]
Abstract
Coherent phonons can be launched in materials upon localized pulsed optical excitation, and be subsequently followed in time-domain, with a sub-picosecond resolution, using a time-delayed pulsed probe. This technique yields characterization of mechanical, optical, and electronic properties at the nanoscale, and is taken advantage of for investigations in material science, physics, chemistry, and biology. Here we review the use of this experimental method applied to the emerging field of homo- and heterostructures of van der Waals materials. Their unique structure corresponding to non-covalently stacked atomically thin layers allows for the study of original structural configurations, down to one-atom-thin films free of interface defect. The generation and relaxation of coherent optical phonons, as well as propagative and resonant breathing acoustic phonons, are comprehensively discussed. This approach opens new avenues for the in situ characterization of these novel materials, the observation and modulation of exotic phenomena, and advances in the field of acoustics microscopy.
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Affiliation(s)
- Fabien Vialla
- Institut Lumière Matière UMR 5306, Université Claude Bernard Lyon 1, CNRS, Université de Lyon, F-69622 Villeurbanne, France;
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14
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Bobb JA, Rodrigues CJ, El-Shall MS, Tibbetts KM. Laser-assisted synthesis of gold-graphene oxide nanocomposites: effect of pulse duration. Phys Chem Chem Phys 2020; 22:18294-18303. [PMID: 32785346 DOI: 10.1039/d0cp02953j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Laser photoreduction of metal ions onto graphene oxide (GO) is a facile, environmentally friendly method to produce functional metal-GO nanocomposites for a variety of applications. This work compares Au-GO nanocomposites prepared by photoreduction of [AuCl4]- in aqueous GO solution using laser pulses of nanosecond (ns) and femtosecond (fs) duration. The presence of GO significantly accelerates the [AuCl4]- photoreduction rate, with a more pronounced effect using ns laser pulses. This difference is rationalized in terms of the stronger interaction of the 532 nm laser wavelength and long pulse duration with the GO. Both the ns and fs lasers produce significant yields of sub-4 nm Au nanoparticles attached to GO, albeit with different size distributions: a broad 5.8 ± 1.9 nm distribution for the ns laser and two distinct distributions of 3.5 ± 0.8 and 10.1 ± 1.4 nm for the fs laser. Despite these differences, both Au-GO nanocomposites had the same high catalytic activity towards p-nitrophenol reduction as compared to unsupported 4-5 nm Au nanoparticles. These results point to the key role of GO photoexcitation in catalyzing metal ion reduction and indicate that both ns and fs lasers are suitable for producing functional metal-GO nanocomposites.
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Affiliation(s)
- Julian A Bobb
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, USA.
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15
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Demirci S, Gürel HH, Jahangirov S, Ciraci S. Temperature, strain and charge mediated multiple and dynamical phase changes of selenium and tellurium. NANOSCALE 2020; 12:3249-3258. [PMID: 31970352 DOI: 10.1039/c9nr06069c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Semiconducting selenium and tellurium in their 3D bulk trigonal structures consist of parallel and weakly interacting helical chains of atoms and display a number of peculiarities. We predict that thermal excitations, 2D compressive strain and excess charge of positive and negative polarity mediate metal-insulator transitions by transforming these semiconductors into different metallic crystal structures. When heated to high temperature, or compressed, or charged positively, they change into a simple cubic structure with metallic bands, which is very rare among elemental crystals. When charged negatively, they transform first into body-centered tetragonal and subsequently into the body-centered orthorhombic structures with increasing negative charging. These two new structures stabilized by excess electrons also have overlapping metallic bands and quasi 2D and 1D substructures of lower dimensionality. Since the external charging of crystals can be achieved through their surfaces, the effects of charging on 2D structures of selenium and tellurium are also investigated. Similar structural transformations have been mediated also in 2D nanosheets and free-standing monolayers of these elements. These phase changes assisted by phonons are dynamical, reversible and tunable; the resulting metal-insulator transitions can occur within very short time intervals and may offer important device applications.
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Affiliation(s)
- Salih Demirci
- UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey.
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16
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Tinnemann V, Streubühr C, Hafke B, Witte T, Kalus A, Hanisch-Blicharski A, Ligges M, Zhou P, von der Linde D, Bovensiepen U, Horn-von Hoegen M. Decelerated lattice excitation and absence of bulk phonon modes at surfaces: Ultra-fast electron diffraction from Bi(111) surface upon fs-laser excitation. Struct Dyn 2019; 6:065101. [PMID: 31700944 PMCID: PMC6831505 DOI: 10.1063/1.5128275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/15/2019] [Indexed: 12/30/2022] Open
Abstract
Ultrafast reflection high-energy electron diffraction is employed to follow the lattice excitation of a Bi(111) surface upon irradiation with a femtosecond laser pulse. The thermal motion of the atoms is analyzed through the Debye–Waller effect. While the Bi bulk is heated on time scales of 2 to 4 ps, we observe that the excitation of vibrational motion of the surface atoms occurs much slower with a time constant of 12 ps. This transient nonequilibrium situation is attributed to the weak coupling between bulk and surface phonon modes which hampers the energy flow between the two subsystems. From the absence of a fast component in the transient diffraction intensity, it is in addition concluded that truncated bulk phonon modes are absent at the surface.
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Affiliation(s)
- V. Tinnemann
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - C. Streubühr
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - B. Hafke
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - T. Witte
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - A. Kalus
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - A. Hanisch-Blicharski
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - M. Ligges
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - P. Zhou
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - D. von der Linde
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - U. Bovensiepen
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - M. Horn-von Hoegen
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
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17
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Li Z, Xiao RJ, Xu P, Zhu C, Sun S, Zheng D, Wang H, Zhang M, Tian H, Yang HX, Li JQ. Lattice Dynamics and Contraction of Energy Bandgap in Photoexcited Semiconducting Boron Nitride Nanotubes. ACS NANO 2019; 13:11623-11631. [PMID: 31532630 DOI: 10.1021/acsnano.9b05466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Structural dynamics and changes in electronic structures driven by photoexcited carriers are critical issues in both semiconducting and optoelectronic nanodevices. Herein, a phase diagram for the transient states and relevant dynamic processes in multiwalled boron nitride nanotubes (BNNTs) has been extensively studied for a full reversible cycle after a fs-laser excitation in ultrafast TEMs, and the significant structural features and evolution of electronic natures have been investigated using pulsed electron diffraction and femtosecond-resolved electron energy-loss spectroscopy (EELS). It is revealed that nonthermal anisotropic alterations of the lattice apparently precede the phonon-driven thermal transients along the radial and axial directions. Ab initio calculations support these findings and show that electrons excited from the π to π* orbitals in the BN nanotubes weaken the intralayer bonds while strengthening the interlayer bonds along the radial direction. Importantly, time-resolved EELS measurements show contraction of the energy bandgap after fs-laser excitation associated with nonthermal structural transients. This fact verifies that laser-induced bandgap renormalization in semiconductors can essentially be correlated with both the rapid processes of excited carriers and nonthermal lattice evolution.
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Affiliation(s)
- Zhongwen Li
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Rui-Juan Xiao
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Peng Xu
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Chunhui Zhu
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Shuaishuai Sun
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Dingguo Zheng
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Hong Wang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Ming Zhang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Huanfang Tian
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
| | - Huai-Xin Yang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
- Yangtze River Delta Physics Research Center Co., Ltd. , Liyang , Jiangsu 213300 , China
| | - Jian-Qi Li
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , China
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18
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Abstract
A review that summarizes the most recent technological developments in the field of ultrafast structural dynamics with focus on the use of ultrashort X-ray and electron pulses follows. Atomistic views of chemical processes and phase transformations have long been the exclusive domain of computer simulators. The advent of femtosecond (fs) hard X-ray and fs-electron diffraction techniques made it possible to bring such a level of scrutiny to the experimental area. The following review article provides a summary of the main ultrafast techniques that enabled the generation of atomically resolved movies utilizing ultrashort X-ray and electron pulses. Recent advances are discussed with emphasis on synchrotron-based methods, tabletop fs-X-ray plasma sources, ultrabright fs-electron diffractometers, and timing techniques developed to further improve the temporal resolution and fully exploit the use of intense and ultrashort X-ray free electron laser (XFEL) pulses.
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Wang X, Jarnac A, Ekström JC, Bengtsson ÅUJ, Dorchies F, Enquist H, Jurgilaitis A, Pedersen MN, Tu CM, Wulff M, Larsson J. Generation of a large compressive strain wave in graphite by ultrashort-pulse laser irradiation. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:024501. [PMID: 30915389 PMCID: PMC6422787 DOI: 10.1063/1.5089291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 03/04/2019] [Indexed: 06/09/2023]
Abstract
We have studied strain wave generation in graphite induced by an intense ultrashort laser pulse. The study was performed in the intensity regime above the ablation threshold of graphite. The aim was to maximize the strain and, thus, also the internal pressure (stress). Laser pulses with a 1 ps temporal duration melt the surface of graphite resulting in a molten material which initially exists at the solid density. As the molten material expands, a compressive strain wave starts propagating into the crystal below the molten layer. The strain pulse was studied with time-resolved X-ray diffraction. At a temporal delay of 100 ps after laser excitation, we observed >10% compressive strain, which corresponds to a pressure of 7.2 GPa. This strain could be reproduced by hydrodynamic simulations, which also provided a temperature map as a function of time and depth.
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Affiliation(s)
- Xiaocui Wang
- Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | | | - J. C. Ekström
- Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - Å. U. J. Bengtsson
- Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - F. Dorchies
- Université de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - H. Enquist
- MAX IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - A. Jurgilaitis
- MAX IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - M. N. Pedersen
- ESRF-The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - C.-M. Tu
- Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - M. Wulff
- ESRF-The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - J. Larsson
- Author to whom correspondence should be addressed:
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20
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Mancini GF, Pennacchio F, Latychevskaia T, Reguera J, Stellacci F, Carbone F. Local photo-mechanical stiffness revealed in gold nanoparticles supracrystals by ultrafast small-angle electron diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:024304. [PMID: 31041361 PMCID: PMC6461555 DOI: 10.1063/1.5091858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 03/27/2019] [Indexed: 05/03/2023]
Abstract
We demonstrate that highly ordered two-dimensional crystals of ligand-capped gold nanoparticles display a local photo-mechanical stiffness as high as that of solids such as graphite. In out-of-equilibrium electron diffraction experiments, a strong temperature jump is induced in a thin film with a femtosecond laser pulse. The initial electronic excitation transfers energy to the underlying structural degrees of freedom, with a rate generally proportional to the stiffness of the material. Using femtosecond small-angle electron diffraction, we observe the temporal evolution of the diffraction feature associated with the nearest-neighbor nanoparticle distance. The Debye-Waller decay for the octanethiol-capped nanoparticle supracrystal, in particular, is found to be unexpectedly fast, almost as fast as the stiffest solid known and observed by the same technique, i.e., graphite. Our observations unravel that local stiffness in a dense supramolecular assembly can be created by van der Waals interactions up to a level comparable to crystalline systems characterized by covalent bonding.
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Affiliation(s)
| | - Francesco Pennacchio
- Laboratory for Ultrafast Microscopy and Electron Scattering, Lausanne Center for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Tatiana Latychevskaia
- Physics Institute, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Javier Reguera
- CIC biomaGUNE, Paseo de Miramón 182C, 20014 Donostia-San Sebastian, Spain and Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
| | - Francesco Stellacci
- Supramolecular Nanomaterials and Interfaces Laboratory, Institute of Materials, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Fabrizio Carbone
- Laboratory for Ultrafast Microscopy and Electron Scattering, Lausanne Center for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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21
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Sun S, Li Z, Li ZA, Xiao R, Zhang M, Tian H, Yang H, Li J. Cooperative inter- and intra-layer lattice dynamics of photoexcited multi-walled carbon nanotubes studied by ultrafast electron diffraction. NANOSCALE 2018; 10:7465-7471. [PMID: 29637987 DOI: 10.1039/c8nr00432c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Optical tuning and probing ultrafast structural response of nanomaterials driven by electronic excitation constitute a challenging but promising approach for understanding microscopic mechanisms and applications in microelectromechanical systems and optoelectrical devices. Here we use pulsed electron diffraction in a transmission electron microscope to investigate laser-induced tubular lattice dynamics of multi-walled carbon nanotubes (MWCNTs) with varying laser fluence and initial specimen temperature. Our photoexcitation experiments demonstrate cooperative and inverse collective atomic motions in intralayer and interlayer directions, whose strengths and rates depend on pump fluence. The electron-driven and thermally driven structural responses with opposite amplitudes cause a crossover between intralayer and interlayer directions. Our ab initio calculations support these findings and reveal that electrons excited from π to π* orbitals in a carbon tube weaken the intralayer bonds while strengthening the interlayer bonds along the radial direction. Moreover, by probing the structural dynamics of MWCNTs at initial temperatures of 300 and 100 K, we uncover the concomitance of thermal and nonthermal dynamical processes and their mutual influence in MWCNTs. Our results illustrate the nature of electron-driven nonthermal process and electron-phonon thermalization in the MWCNTs, and bear implications for the intricate energy conversion and transfer in materials at the nanoscale.
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Affiliation(s)
- Shuaishuai Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
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22
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Feist A, Rubiano da Silva N, Liang W, Ropers C, Schäfer S. Nanoscale diffractive probing of strain dynamics in ultrafast transmission electron microscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:014302. [PMID: 29464187 PMCID: PMC5801750 DOI: 10.1063/1.5009822] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 11/21/2017] [Indexed: 05/31/2023]
Abstract
The control of optically driven high-frequency strain waves in nanostructured systems is an essential ingredient for the further development of nanophononics. However, broadly applicable experimental means to quantitatively map such structural distortion on their intrinsic ultrafast time and nanometer length scales are still lacking. Here, we introduce ultrafast convergent beam electron diffraction with a nanoscale probe beam for the quantitative retrieval of the time-dependent local deformation gradient tensor. We demonstrate its capabilities by investigating the ultrafast acoustic deformations close to the edge of a single-crystalline graphite membrane. Tracking the structural distortion with a 28-nm/700-fs spatio-temporal resolution, we observe an acoustic membrane breathing mode with spatially modulated amplitude, governed by the optical near field structure at the membrane edge. Furthermore, an in-plane polarized acoustic shock wave is launched at the membrane edge, which triggers secondary acoustic shear waves with a pronounced spatio-temporal dependency. The experimental findings are compared to numerical acoustic wave simulations in the continuous medium limit, highlighting the importance of microscopic dissipation mechanisms and ballistic transport channels.
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Affiliation(s)
- Armin Feist
- 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Nara Rubiano da Silva
- 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Wenxi Liang
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China
| | | | - Sascha Schäfer
- 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany
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23
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Mannebach EM, Nyby C, Ernst F, Zhou Y, Tolsma J, Li Y, Sher MJ, Tung IC, Zhou H, Zhang Q, Seyler KL, Clark G, Lin Y, Zhu D, Glownia JM, Kozina ME, Song S, Nelson S, Mehta A, Yu Y, Pant A, Aslan B, Raja A, Guo Y, DiChiara A, Mao W, Cao L, Tongay S, Sun J, Singh DJ, Heinz TF, Xu X, MacDonald AH, Reed E, Wen H, Lindenberg AM. Dynamic Optical Tuning of Interlayer Interactions in the Transition Metal Dichalcogenides. NANO LETTERS 2017; 17:7761-7766. [PMID: 29119791 DOI: 10.1021/acs.nanolett.7b03955] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Modulation of weak interlayer interactions between quasi-two-dimensional atomic planes in the transition metal dichalcogenides (TMDCs) provides avenues for tuning their functional properties. Here we show that above-gap optical excitation in the TMDCs leads to an unexpected large-amplitude, ultrafast compressive force between the two-dimensional layers, as probed by in situ measurements of the atomic layer spacing at femtosecond time resolution. We show that this compressive response arises from a dynamic modulation of the interlayer van der Waals interaction and that this represents the dominant light-induced stress at low excitation densities. A simple analytic model predicts the magnitude and carrier density dependence of the measured strains. This work establishes a new method for dynamic, nonequilibrium tuning of correlation-driven dispersive interactions and of the optomechanical functionality of TMDC quasi-two-dimensional materials.
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Affiliation(s)
- Ehren M Mannebach
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
| | - Clara Nyby
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Friederike Ernst
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Yao Zhou
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
| | - John Tolsma
- Department of Physics, University of Texas, Austin , Austin, Texas 78712, United States
| | - Yao Li
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
| | - Meng-Ju Sher
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- Department of Physics, Wesleyan University , Middleton, Connecticut 06459, United States
| | - I-Cheng Tung
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Hua Zhou
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Qi Zhang
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Kyle L Seyler
- Department of Physics, University of Washington , Seattle, Washington 98195, United States
| | - Genevieve Clark
- Department of Physics, University of Washington , Seattle, Washington 98195, United States
| | - Yu Lin
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- Department of Geological Sciences, Stanford University , Stanford, California 94305, United States
| | - Diling Zhu
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - James M Glownia
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Michael E Kozina
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Sanghoon Song
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Silke Nelson
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Apurva Mehta
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Yifei Yu
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Anupum Pant
- School for Engineering of Matter, Transport, and Energy, Arizona State University , Tempe, Arizona 85287, United States
| | - Burak Aslan
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
| | - Archana Raja
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Yinsheng Guo
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Anthony DiChiara
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Wendy Mao
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- Department of Geological Sciences, Stanford University , Stanford, California 94305, United States
| | - Linyou Cao
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport, and Energy, Arizona State University , Tempe, Arizona 85287, United States
| | - Jifeng Sun
- Department of Physics and Astronomy, University of Missouri , Columbia, Missouri 65211-7010, United States
| | - David J Singh
- Department of Physics and Astronomy, University of Missouri , Columbia, Missouri 65211-7010, United States
| | - Tony F Heinz
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Xiaodong Xu
- Department of Physics, University of Washington , Seattle, Washington 98195, United States
| | - Allan H MacDonald
- Department of Physics, University of Texas, Austin , Austin, Texas 78712, United States
| | - Evan Reed
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Haidan Wen
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Aaron M Lindenberg
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
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24
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Structures and ultrafast dynamics of interfacial water assemblies on smooth hydrophobic surfaces. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.01.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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25
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Pennacchio F, Vanacore GM, Mancini GF, Oppermann M, Jayaraman R, Musumeci P, Baum P, Carbone F. Design and implementation of an optimal laser pulse front tilting scheme for ultrafast electron diffraction in reflection geometry with high temporal resolution. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:044032. [PMID: 28713841 PMCID: PMC5491388 DOI: 10.1063/1.4991483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/21/2017] [Indexed: 06/07/2023]
Abstract
Ultrafast electron diffraction is a powerful technique to investigate out-of-equilibrium atomic dynamics in solids with high temporal resolution. When diffraction is performed in reflection geometry, the main limitation is the mismatch in group velocity between the overlapping pump light and the electron probe pulses, which affects the overall temporal resolution of the experiment. A solution already available in the literature involved pulse front tilt of the pump beam at the sample, providing a sub-picosecond time resolution. However, in the reported optical scheme, the tilted pulse is characterized by a temporal chirp of about 1 ps at 1 mm away from the centre of the beam, which limits the investigation of surface dynamics in large crystals. In this paper, we propose an optimal tilting scheme designed for a radio-frequency-compressed ultrafast electron diffraction setup working in reflection geometry with 30 keV electron pulses containing up to 105 electrons/pulse. To characterize our scheme, we performed optical cross-correlation measurements, obtaining an average temporal width of the tilted pulse lower than 250 fs. The calibration of the electron-laser temporal overlap was obtained by monitoring the spatial profile of the electron beam when interacting with the plasma optically induced at the apex of a copper needle (plasma lensing effect). Finally, we report the first time-resolved results obtained on graphite, where the electron-phonon coupling dynamics is observed, showing an overall temporal resolution in the sub-500 fs regime. The successful implementation of this configuration opens the way to directly probe structural dynamics of low-dimensional systems in the sub-picosecond regime, with pulsed electrons.
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Affiliation(s)
- Francesco Pennacchio
- Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Giovanni M Vanacore
- Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Giulia F Mancini
- JILA, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, USA
| | - Malte Oppermann
- Laboratory of Ultrafast Spectroscopy, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Rajeswari Jayaraman
- Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Pietro Musumeci
- Particle Beam Physics Laboratory, Department of Physics and Astronomy, UCLA, Los Angeles, California 90095, USA
| | - Peter Baum
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany
| | - Fabrizio Carbone
- Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Chergui M, Thomas JM. From structure to structural dynamics: Ahmed Zewail's legacy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:043802. [PMID: 28868324 PMCID: PMC5562505 DOI: 10.1063/1.4998243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 08/08/2017] [Indexed: 05/19/2023]
Abstract
In this brief tribute to Ahmed Zewail, we highlight and place in the historical context, several of the major achievements that he and his colleagues have made in Femtochemistry (of which he was the principal instigator) and his introduction of ultrafast electron scattering, diffraction, microscopy and spectroscopy. By achieving a sub-picosecond temporal resolution, coupled with a picometer spatial resolution, he revolutionised our understanding of the corpus of chemical, physical, biological and materials science systems.
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Affiliation(s)
- Majed Chergui
- Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Spectroscopie Ultrarapide and Lausanne Centre for Ultrafast Science (LACUS), ISIC, Faculté des Sciences de Base, Station 6, CH-1015 Lausanne, Switzerland
| | - John Meurig Thomas
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB30FS, United Kingdom
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Vanacore GM, Hu J, Liang W, Bietti S, Sanguinetti S, Carbone F, Zewail AH. Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:044034. [PMID: 28852685 PMCID: PMC5552391 DOI: 10.1063/1.4998009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 07/28/2017] [Indexed: 05/31/2023]
Abstract
Understanding the dynamics of atomic vibrations confined in quasi-zero dimensional systems is crucial from both a fundamental point-of-view and a technological perspective. Using ultrafast electron diffraction, we monitored the lattice dynamics of GaAs quantum dots-grown by Droplet Epitaxy on AlGaAs-with sub-picosecond and sub-picometer resolutions. An ultrafast laser pulse nearly resonantly excites a confined exciton, which efficiently couples to high-energy acoustic phonons through the deformation potential mechanism. The transient behavior of the measured diffraction pattern reveals the nonequilibrium phonon dynamics both within the dots and in the region surrounding them. The experimental results are interpreted within the theoretical framework of a non-Markovian decoherence, according to which the optical excitation creates a localized polaron within the dot and a travelling phonon wavepacket that leaves the dot at the speed of sound. These findings indicate that integration of a phononic emitter in opto-electronic devices based on quantum dots for controlled communication processes can be fundamentally feasible.
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Affiliation(s)
| | | | | | - Sergio Bietti
- L-NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 53, I-20125 Milano, Italy
| | - Stefano Sanguinetti
- L-NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 53, I-20125 Milano, Italy
| | - Fabrizio Carbone
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Ahmed H Zewail
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA
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Miyamoto Y, Zhang H, Miyazaki T, Rubio A. Modifying the interlayer interaction in layered materials with an intense IR laser. PHYSICAL REVIEW LETTERS 2015; 114:116102. [PMID: 25839294 DOI: 10.1103/physrevlett.114.116102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Indexed: 06/04/2023]
Abstract
We propose a transient interlayer compression in two-dimensional compound materials by using an intense IR laser resonant with the out-of-plane optical phonon mode (A(2u) mode). As a test case, we studied bilayer hexagonal boron nitride (h-BN), which is one of the compound layered materials. Excited state molecular dynamics calculations using time-dependent density functional theory show an 11.3% transient interlayer contraction of h-BN due to an interlayer dipole-dipole attraction of the laser-pumped A(2u) mode. These results are applicable to other layered compound materials. Such layered materials are a good material for nanospace chemistry, e.g., intercalating molecules and acting with them, and IR irradiation to contract the interlayer distance could provide a new route for chemical reactions under pressure. The duration of the contraction is at least 1 ps in the current simulation, which is observable by high-speed electron-beam diffraction measurements.
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Affiliation(s)
- Yoshiyuki Miyamoto
- Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba 305-8568, Japan
| | - Hong Zhang
- College of Physical Science and Technology, Sichuan University, Chengdu 610065, China
| | - Takehide Miyazaki
- Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba 305-8568, Japan
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
- Nano-Bio Spectroscopy group and European Theoretical Spectroscopy Facility (ETSF), Universidad del País Vasco CFM CSIC-UPV/EHU-MPC DIPC, 20018 San Sebastian, Spain
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van der Veen RM, Penfold TJ, Zewail AH. Ultrafast core-loss spectroscopy in four-dimensional electron microscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2015; 2:024302. [PMID: 26798793 PMCID: PMC4711615 DOI: 10.1063/1.4916897] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 03/23/2015] [Indexed: 05/06/2023]
Abstract
We demonstrate ultrafast core-electron energy-loss spectroscopy in four-dimensional electron microscopy as an element-specific probe of nanoscale dynamics. We apply it to the study of photoexcited graphite with femtosecond and nanosecond resolutions. The transient core-loss spectra, in combination with ab initio molecular dynamics simulations, reveal the elongation of the carbon-carbon bonds, even though the overall behavior is a contraction of the crystal lattice. A prompt energy-gap shrinkage is observed on the picosecond time scale, which is caused by local bond length elongation and the direct renormalization of band energies due to temperature-dependent electron-phonon interactions.
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Affiliation(s)
| | - Thomas J Penfold
- SwissFEL, Paul Scherrer Institut , 5232 Villigen PSI, Switzerland
| | - Ahmed H Zewail
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology , Pasadena, California 91125, USA
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Carbone F. Dynamics deep from the core. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2015; 2:020601. [PMID: 26798787 PMCID: PMC4711669 DOI: 10.1063/1.4918727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/06/2015] [Accepted: 04/10/2015] [Indexed: 06/05/2023]
Abstract
In van der Veen et al., [Struct. Dyn. 2, 024302 (2015)], femtosecond and nanosecond electron energy loss spectroscopy of deep core-levels are demonstrated. These results pave the way to the investigation of materials and molecules with combined energy, time, and spatial resolution in a transmission electron microscope. Furthermore, the authors elucidate the role of the electron phonon coupling in the band-gap renormalization that takes place in graphite upon photo-excitation.
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Affiliation(s)
- F Carbone
- Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), Institute of Condensed Matter Physics (ICMP), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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31
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Chatelain RP, Morrison VR, Klarenaar BLM, Siwick BJ. Coherent and incoherent electron-phonon coupling in graphite observed with radio-frequency compressed ultrafast electron diffraction. PHYSICAL REVIEW LETTERS 2014; 113:235502. [PMID: 25526134 DOI: 10.1103/physrevlett.113.235502] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Indexed: 05/06/2023]
Abstract
Radio-frequency compressed ultrafast electron diffraction has been used to probe the coherent and incoherent coupling of impulsive electronic excitation at 1.55 eV (800 nm) to optical and acoustic phonon modes directly from the perspective of the lattice degrees of freedom. A biexponential suppression of diffracted intensity due to relaxation of the electronic system into incoherent phonons is observed, with the 250 fs fast contribution dominated by coupling to the E_{2g2} optical phonon mode at the Γ point (Γ-E_{2g2}) and A_{1}^{'} optical phonon mode at the K point (K-A_{1}^{'}). Both modes have Kohn anomalies at these points in the Brillouin zone. The result is a unique nonequilibrium state with the electron subsystem in thermal equilibrium with only a very small subset of the lattice degrees of freedom within 500 fs following photoexcitation. This state relaxes through further electron-phonon and phonon-phonon pathways on the 6.5 ps time scale. In addition, electronic excitation leads to both in-plane and out-of-plane coherent lattice responses in graphite whose character we are able to fully determine based on spot positions and intensity modulations in the femtosecond electron diffraction data. The in-plane motion is specifically a Γ point shearing mode of the graphene planes and the out-of-plane motion an acoustic breathing mode response of the film.
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Affiliation(s)
- Robert P Chatelain
- Departments of Physics and Chemistry, Center for the Physics of Materials, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
| | - Vance R Morrison
- Departments of Physics and Chemistry, Center for the Physics of Materials, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
| | - Bart L M Klarenaar
- Departments of Physics and Chemistry, Center for the Physics of Materials, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
| | - Bradley J Siwick
- Departments of Physics and Chemistry, Center for the Physics of Materials, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
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Vanacore GM, Hu J, Liang W, Bietti S, Sanguinetti S, Zewail AH. Diffraction of quantum dots reveals nanoscale ultrafast energy localization. NANO LETTERS 2014; 14:6148-54. [PMID: 25099123 DOI: 10.1021/nl502293a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Unlike in bulk materials, energy transport in low-dimensional and nanoscale systems may be governed by a coherent "ballistic" behavior of lattice vibrations, the phonons. If dominant, such behavior would determine the mechanism for transport and relaxation in various energy-conversion applications. In order to study this coherent limit, both the spatial and temporal resolutions must be sufficient for the length-time scales involved. Here, we report observation of the lattice dynamics in nanoscale quantum dots of gallium arsenide using ultrafast electron diffraction. By varying the dot size from h = 11 to 46 nm, the length scale effect was examined, together with the temporal change. When the dot size is smaller than the inelastic phonon mean-free path, the energy remains localized in high-energy acoustic modes that travel coherently within the dot. As the dot size increases, an energy dissipation toward low-energy phonons takes place, and the transport becomes diffusive. Because ultrafast diffraction provides the atomic-scale resolution and a sufficiently high time resolution, other nanostructured materials can be studied similarly to elucidate the nature of dynamical energy localization.
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Affiliation(s)
- Giovanni M Vanacore
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology , Pasadena, California 91125, United States
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33
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Piazza L, Musumeci P, Luiten O, Carbone F. A proposal for fs-electron microscopy experiments on high-energy excitations in solids. Micron 2014; 63:40-6. [DOI: 10.1016/j.micron.2014.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 11/13/2022]
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34
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Lahme S, Kealhofer C, Krausz F, Baum P. Femtosecond single-electron diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2014; 1:034303. [PMID: 26798778 PMCID: PMC4711605 DOI: 10.1063/1.4884937] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 06/12/2014] [Indexed: 05/06/2023]
Abstract
Ultrafast electron diffraction allows the tracking of atomic motion in real time, but space charge effects within dense electron packets are a problem for temporal resolution. Here, we report on time-resolved pump-probe diffraction using femtosecond single-electron pulses that are free from intra-pulse Coulomb interactions over the entire trajectory from the source to the detector. Sufficient average electron current is achieved at repetition rates of hundreds of kHz. Thermal load on the sample is avoided by minimizing the pump-probe area and by maximizing heat diffusion. Time-resolved diffraction from fibrous graphite polycrystals reveals coherent acoustic phonons in a nanometer-thick grain ensemble with a signal-to-noise level comparable to conventional multi-electron experiments. These results demonstrate the feasibility of pump-probe diffraction in the single-electron regime, where simulations indicate compressibility of the pulses down to few-femtosecond and attosecond duration.
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Affiliation(s)
- S Lahme
- Max-Planck-Institute of Quantum Optics and Ludwig-Maximilians-Universität München , Am Coulombwall 1, 85748 Garching, Germany
| | - C Kealhofer
- Max-Planck-Institute of Quantum Optics and Ludwig-Maximilians-Universität München , Am Coulombwall 1, 85748 Garching, Germany
| | - F Krausz
- Max-Planck-Institute of Quantum Optics and Ludwig-Maximilians-Universität München , Am Coulombwall 1, 85748 Garching, Germany
| | - P Baum
- Max-Planck-Institute of Quantum Optics and Ludwig-Maximilians-Universität München , Am Coulombwall 1, 85748 Garching, Germany
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35
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Morimoto Y, Kanya R, Yamanouchi K. Laser-assisted electron diffraction for femtosecond molecular imaging. J Chem Phys 2014; 140:064201. [DOI: 10.1063/1.4863985] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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36
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Baum P. On the physics of ultrashort single-electron pulses for time-resolved microscopy and diffraction. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2013.06.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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37
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Arnaud B, Giret Y. Electron cooling and debye-waller effect in photoexcited bismuth. PHYSICAL REVIEW LETTERS 2013; 110:016405. [PMID: 23383816 DOI: 10.1103/physrevlett.110.016405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Indexed: 06/01/2023]
Abstract
By means of first principles calculations, we compute the effective electron-phonon coupling constant G(0) governing the electron cooling in photoexcited bismuth. G(0) strongly increases as a function of electron temperature, which can be traced back to the semimetallic nature of bismuth. We also use a thermodynamical model to compute the time evolution of both electron and lattice temperatures following laser excitation. Thereby, we simulate the time evolution of (1 -1 0), (-2 1 1) and (2 -2 0) Bragg peak intensities measured by Sciaini et al. [Nature (London) 458, 56 (2009)] in femtosecond electron diffraction experiments. The effect of the electron temperature on the Debye-Waller factors through the softening of all optical modes across the whole Brillouin zone turns out to be crucial to reproduce the time evolution of these Bragg peak intensities.
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Affiliation(s)
- B Arnaud
- Institut de Physique de Rennes, UMR UR1-CNRS 6251, Campus de Beaulieu-Bat 11 A, 35042 Rennes Cedex, France
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38
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Scoby CM, Li RK, Musumeci P. Effect of an ultrafast laser induced plasma on a relativistic electron beam to determine temporal overlap in pump-probe experiments. Ultramicroscopy 2012; 127:14-8. [PMID: 22951263 DOI: 10.1016/j.ultramic.2012.07.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper we report on a simple and robust method to measure the absolute temporal overlap of the laser and the electron beam at the sample based on the effect of a laser induced plasma on the electron beam transverse distribution, successfully extending a similar method from keV to MeV electron beams. By pumping a standard copper TEM grid to form the plasma, we gain timing information independent of the sample under study. In experiments discussed here the optical delay to achieve temporal overlap between the pump electron beam and probe laser can be determined with ~1 ps precision.
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Affiliation(s)
- Cheyne M Scoby
- UCLA Department of Physics, 475 Portola Plaza, Los Angeles, CA 90095-1547, USA.
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40
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Carbone F, Musumeci P, Luiten O, Hebert C. A perspective on novel sources of ultrashort electron and X-ray pulses. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2011.10.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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41
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Schäfer S, Liang W, Zewail AH. Structural dynamics of surfaces by ultrafast electron crystallography: Experimental and multiple scattering theory. J Chem Phys 2011; 135:214201. [DOI: 10.1063/1.3663963] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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42
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Pagliara S, Galimberti G, Mor S, Montagnese M, Ferrini G, Grandi MS, Galinetto P, Parmigiani F. Photoinduced π−π* Band Gap Renormalization in Graphite. J Am Chem Soc 2011; 133:6318-22. [PMID: 21452870 DOI: 10.1021/ja1110738] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. Pagliara
- Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia, Italy
| | - G. Galimberti
- Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia, Italy
| | - S. Mor
- Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia, Italy
| | - M. Montagnese
- Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia, Italy
| | - G. Ferrini
- Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia, Italy
| | - M. S. Grandi
- Dipartimento di Fisica, Università di Pavia, I-27100 Pavia, Italy
| | - P. Galinetto
- Dipartimento di Fisica, Università di Pavia, I-27100 Pavia, Italy
| | - F. Parmigiani
- Dipartimento di Fisica, Università di Trieste and Sincrotrone Trieste, I-34012 Basovizza, Trieste, Italy
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Nagel M, Michalski A, Botzem T, Kurz H. Near-field investigation of THz surface-wave emission from optically excited graphite flakes. OPTICS EXPRESS 2011; 19:4667-4672. [PMID: 21369298 DOI: 10.1364/oe.19.004667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
THz emission from an unbiased graphite flake after optical sub-ps pulse inter-band excitation is measured using a novel micro-machined photoconductive probe-tip. Oscillatory behavior of the measured THz near-field emission is shown to originate from electromagnetic eigenmode resonances of the laterally limited graphite flake. The excitation efficiency of the lowest order eigenmode resonances strongly dependents on optical pump location. From this data a radial symmetric charge carrier translocation at the pump location is revealed as the dominating THz surface-wave emission effect. Measurements show good agreement with numerical field simulations of the eigenmode center frequencies and the spectral response expected for THz emission through basal plane oriented radial current surge excitation.
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Affiliation(s)
- M Nagel
- Institut for Halbleitertechnik, RWTH Aachen University, Aachen, Germany.
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44
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Carbone F, Aubock G, Cannizzo A, Van Mourik F, Nair R, Geim A, Novoselov K, Chergui M. Femtosecond carrier dynamics in bulk graphite and graphene paper. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.01.052] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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45
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Moussa S, Atkinson G, SamyEl-Shall M, Shehata A, AbouZeid KM, Mohamed MB. Laser assisted photocatalytic reduction of metal ions by graphene oxide. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm11228g] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Abstract
Visualization of atomic-scale structural motion by ultrafast electron diffraction and microscopy requires electron packets of shortest duration and highest coherence. We report on the generation and application of single-electron pulses for this purpose. Photoelectric emission from metal surfaces is studied with tunable ultraviolet pulses in the femtosecond regime. The bandwidth, efficiency, coherence, and electron pulse duration are investigated in dependence on excitation wavelength, intensity, and laser bandwidth. At photon energies close to the cathode's work function, the electron pulse duration shortens significantly and approaches a threshold that is determined by interplay of the optical pulse width and the acceleration field. An optimized choice of laser wavelength and bandwidth results in sub-100-fs electron pulses. We demonstrate single-electron diffraction from polycrystalline diamond films and reveal the favorable influences of matched photon energies on the coherence volume of single-electron wave packets. We discuss the consequences of our findings for the physics of the photoelectric effect and for applications of single-electron pulses in ultrafast 4D imaging of structural dynamics.
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47
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Acocella A, Carbone F, Zerbetto F. Quantum Study of Laser-Induced Initial Activation of Graphite-to-Diamond Conversion. J Am Chem Soc 2010; 132:12166-7. [DOI: 10.1021/ja102497z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Angela Acocella
- Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via F. Selmi 2, 40126, Bologna, Italy, and DPMC, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Fabrizio Carbone
- Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via F. Selmi 2, 40126, Bologna, Italy, and DPMC, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Francesco Zerbetto
- Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via F. Selmi 2, 40126, Bologna, Italy, and DPMC, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
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49
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Park H, Zuo JM. Comment on "Structural preablation dynamics of graphite observed by ultrafast electron crystallography". PHYSICAL REVIEW LETTERS 2010; 105:059603-059604. [PMID: 20867959 DOI: 10.1103/physrevlett.105.059603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Indexed: 05/29/2023]
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50
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Schäfer S, Liang W, Zewail AH. Structural dynamics and transient electric-field effects in ultrafast electron diffraction from surfaces. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.04.049] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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