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S. Muzas A, Serrano Jiménez A, Zhang Y, Jiang B, Juaristi JI, Alducin M. Multicoverage Study of Femtosecond Laser-Induced Desorption of CO from Pd(111). J Phys Chem Lett 2024; 15:2587-2594. [PMID: 38416783 PMCID: PMC10926157 DOI: 10.1021/acs.jpclett.4c00026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/01/2024] [Accepted: 02/09/2024] [Indexed: 03/01/2024]
Abstract
We study the strong coverage dependence of the femtosecond laser-induced desorption of CO from Pd(111) using molecular dynamics simulations that consistently include the effect of the laser-induced hot electrons on both the adsorbates and surface atoms. Adiabatic forces are obtained from a multicoverage neural network potential energy surface that we construct using data from density functional theory calculations for 0.33 and 0.75 monolayer (ML). Our molecular dynamics simulations performed for these two trained coverages and an additional intermediate coverage of 0.60 ML reproduce well the peculiarities of the experimental findings. The performed simulations also permit us to disentangle the relative role played by the excited electrons and phonons on the desorption process and discover interesting properties of the reaction dynamics as the relevance that the precursor physisorption well acquires during the dynamics as coverage increases.
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Affiliation(s)
- Alberto S. Muzas
- Departamento
de Polímeros y Materiales Avanzados: Física, Química
y Tecnología, Facultad de Químicas (UPV/EHU), Apartado 1072, 20018 Donostia-San Sebastián, Spain
- Centro
de Física de Materiales CFM/MPC (CSIC−UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - Alfredo Serrano Jiménez
- Centro
de Física de Materiales CFM/MPC (CSIC−UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - Yaolong Zhang
- Hefei
National Laboratory for Physical Science at the Microscale, Key Laboratory
of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher
Education Institutes, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s
Republic of China
| | - Bin Jiang
- Hefei
National Laboratory for Physical Science at the Microscale, Key Laboratory
of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher
Education Institutes, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s
Republic of China
| | - J. Iñaki Juaristi
- Departamento
de Polímeros y Materiales Avanzados: Física, Química
y Tecnología, Facultad de Químicas (UPV/EHU), Apartado 1072, 20018 Donostia-San Sebastián, Spain
- Centro
de Física de Materiales CFM/MPC (CSIC−UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Maite Alducin
- Centro
de Física de Materiales CFM/MPC (CSIC−UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
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2
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Tetenoire A, Juaristi JI, Alducin M. Disentangling the role of electrons and phonons in the photoinduced CO desorption and CO oxidation on (O,CO)-Ru(0001). Front Chem 2023; 11:1235176. [PMID: 37521015 PMCID: PMC10380958 DOI: 10.3389/fchem.2023.1235176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/03/2023] [Indexed: 08/01/2023] Open
Abstract
The role played by electronic and phononic excitations in the femtosecond laser induced desorption and oxidation of CO coadsorbed with O on Ru(0001) is investigated using ab initio molecular dynamics with electronic friction. To this aim, simulations that account for both kind of excitations and that only consider electronic excitations are performed. Results for three different surface coverages are obtained. We unequivocally demonstrate that CO desorption is governed by phononic excitations. In the case of oxidation the low statistics does not allow to give a categorical answer. However, the analysis of the adsorbates kinetic energy gain and displacements strongly suggest that phononic excitations and surface distortion also play an important role in the oxidation process.
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Affiliation(s)
- Auguste Tetenoire
- Donostia International Physics Center (DIPC), Donostia-San Sebastian, Spain
| | - J. Iñaki Juaristi
- Donostia International Physics Center (DIPC), Donostia-San Sebastian, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Química (UPV/EHU), Donostia-San Sebastian, Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Donostia-San Sebastian, Spain
| | - Maite Alducin
- Donostia International Physics Center (DIPC), Donostia-San Sebastian, Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Donostia-San Sebastian, Spain
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3
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Tetenoire A, Ehlert C, Juaristi JI, Saalfrank P, Alducin M. Why Ultrafast Photoinduced CO Desorption Dominates over Oxidation on Ru(0001). J Phys Chem Lett 2022; 13:8516-8521. [PMID: 36067002 PMCID: PMC9486938 DOI: 10.1021/acs.jpclett.2c02327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
CO oxidation on Ru(0001) is a long-standing example of a reaction that, being thermally forbidden in ultrahigh vacuum, can be activated by femtosecond laser pulses. In spite of its relevance, the precise dynamics of the photoinduced oxidation process as well as the reasons behind the dominant role of the competing CO photodesorption remain unclear. Here we use ab initio molecular dynamics with electronic friction that account for the highly excited and nonequilibrated system created by the laser to investigate both reactions. Our simulations successfully reproduce the main experimental findings: the existence of photoinduced oxidation and desorption, the large desorption to oxidation branching ratio, and the changes in the O K-edge X-ray absorption spectra attributed to the initial stage of the oxidation process. Now, we are able to monitor in detail the ultrafast CO desorption and CO oxidation occurring in the highly excited system and to disentangle what causes the unexpected inertness to the otherwise energetically favored oxidation.
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Affiliation(s)
- Auguste Tetenoire
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018, Donostia-San Sebastián, Spain
| | - Christopher Ehlert
- Heidelberg
Institute for Theoretical Studies (HITS gGmbH), Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany
- Interdisciplinary
Center for Scientific Computing (IWR), Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer
Feld 205, 69120, Heidelberg, Germany
| | - J. I. Juaristi
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018, Donostia-San Sebastián, Spain
- Departamento
de Polímeros y Materiales Avanzados: Física, Química
y Tecnología, Facultad de Químicas
(UPV/EHU), Apartado 1072, 20080, Donostia-San Sebastián, Spain
- Centro
de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018, Donostia-San Sebastián, Spain
| | - Peter Saalfrank
- Institut
für Chemie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, D-14476, Potsdam, Germany
| | - M. Alducin
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018, Donostia-San Sebastián, Spain
- Centro
de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018, Donostia-San Sebastián, Spain
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Muzas A, Serrano Jiménez A, Ovčar J, Lončarić I, Alducin M, Juaristi JI. Absence of isotope effects in the photo-induced desorption of CO from saturated Pd(111) at high laser fluence. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Serrano Jiménez A, Sánchez Muzas AP, Zhang Y, Ovčar J, Jiang B, Lončarić I, Juaristi JI, Alducin M. Photoinduced Desorption Dynamics of CO from Pd(111): A Neural Network Approach. J Chem Theory Comput 2021; 17:4648-4659. [PMID: 34278798 PMCID: PMC8389528 DOI: 10.1021/acs.jctc.1c00347] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
Modeling the ultrafast
photoinduced dynamics and reactivity of
adsorbates on metals requires including the effect of the laser-excited
electrons and, in many cases, also the effect of the highly excited
surface lattice. Although the recent ab initio molecular dynamics
with electronic friction and thermostats, (Te,Tl)-AIMDEF [AlducinM.;2019, 123, 246802]31922860, enables such complex
modeling, its computational cost may limit its applicability. Here,
we use the new embedded atom neural network (EANN) method [ZhangY.;2019, 10, 496231397157] to develop an accurate and extremely
complex potential energy surface (PES) that allows us a detailed and
reliable description of the photoinduced desorption of CO from the
Pd(111) surface with a coverage of 0.75 monolayer. Molecular dynamics
simulations performed on this EANN-PES reproduce the (Te,Tl)-AIMDEF results with
a remarkable level of accuracy. This demonstrates the outstanding
performance of the obtained EANN-PES that is able to reproduce available
density functional theory (DFT) data for an extensive range of surface
temperatures (90–1000 K); a large number of degrees of freedom,
those corresponding to six CO adsorbates and 24 moving surface atoms;
and the varying CO coverage caused by the abundant desorption events.
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Affiliation(s)
- Alfredo Serrano Jiménez
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - Alberto P Sánchez Muzas
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - Yaolong Zhang
- Hefei National Laboratory for Physical Science at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Juraj Ovčar
- Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia
| | - Bin Jiang
- Hefei National Laboratory for Physical Science at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ivor Lončarić
- Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia.,Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - J Iñaki Juaristi
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain.,Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain.,Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Químicas (UPV/EHU), Apartado 1072, 20080 Donostia-San Sebastián, Spain
| | - Maite Alducin
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain.,Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
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Fujiwara A, Tsurunari Y, Yoshida H, Ohyama J, Yamada T, Haneda M, Miki T, Machida M. Thermal Deactivation of Pd/CeO 2-ZrO 2 Three-Way Catalysts during Real Engine Aging: Analysis by a Surface plus Peripheral Site Model. ACS OMEGA 2020; 5:28897-28906. [PMID: 33195943 PMCID: PMC7659154 DOI: 10.1021/acsomega.0c04644] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 10/16/2020] [Indexed: 06/11/2023]
Abstract
The thermal deactivation of Pd/CeO2-ZrO2 (Pd/CZ) three-way catalysts was studied via nanoscale structural characterization and catalytic kinetic analysis to obtain a fundamental modeling concept for predicting the real catalyst lifetime. The catalysts were engine-aged at 600-1100 °C and used for chassis dynamometer driving test cycles. Observations using an electron microscope and chemisorption experiments showed that the Pd particle size significantly changed in the range of 10-550 nm as a function of aging temperatures. The deactivated catalyst structure was modeled using different-sized hemispherical Pd particles that were in intimate contact with the support surface. Therefore, Pd/CZ contained two types of surface Pd sites residing on the surface of a hemisphere (Pds) and circular periphery of the Pd/CZ interface (Pdb), whereas a reference catalyst, Pd/Al2O3, contained only Pds. In all Pd particle sizes investigated herein, Pd/CZ exhibited higher reaction rates than Pd/Al2O3, which nonlinearly increased with increasing slope as the weight-based number of surface-exposed Pd atoms ([Pds] + [Pdb]) increased. This finding contrasted with that of Pd/Al2O3, where the reaction rate linearly increased with [Pds]. When the Pds sites in both catalysts were equivalent in terms of their specific activities, the activity difference between Pd/CZ and Pd/Al2O3 corresponded to the contribution from Pdb, where oxygen storage/release to/from CZ played a key role. This contribution linearly increased with [Pdb] and therefore decreased with Pd sintering. Although both Pds and Pdb sites showed nearly constant turnover frequencies despite the difference in the Pd particle size, the values for Pdb were more than 2 orders of magnitude greater than those for Pds when assuming a single-atom width one-dimensional Pdb row model. These results suggest that the thermal deterioration of the three-phase boundary site, where Pd, CZ, and the gas phase meet, determines the activity under surface-controlled conditions.
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Affiliation(s)
- Ayumi Fujiwara
- Division
of Materials Science and Chemistry, Faculty of Advanced Science and
Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
| | - Yutaro Tsurunari
- Division
of Materials Science and Chemistry, Faculty of Advanced Science and
Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
| | - Hiroshi Yoshida
- Division
of Materials Science and Chemistry, Faculty of Advanced Science and
Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
- Elements
Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo, Kyoto 615-8245, Japan
| | - Junya Ohyama
- Division
of Materials Science and Chemistry, Faculty of Advanced Science and
Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
- Elements
Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo, Kyoto 615-8245, Japan
| | - Tatsuya Yamada
- Advanced
Ceramics Research Center, Nagoya Institute
of Technology, Tajimi, Gifu 507-0071, Japan
| | - Masaaki Haneda
- Advanced
Ceramics Research Center, Nagoya Institute
of Technology, Tajimi, Gifu 507-0071, Japan
| | - Takeshi Miki
- Innovative
Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology
(AIST), Moriyama, Nagoya 463-8560, Japan
| | - Masato Machida
- Division
of Materials Science and Chemistry, Faculty of Advanced Science and
Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
- Elements
Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo, Kyoto 615-8245, Japan
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7
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Schwermann C, Linden S, Doltsinis NL, Zacharias H. On-Surface Chemistry Induced by Long-Lived Excitons: (NO) 2 Dissociation on C 60. J Phys Chem Lett 2020; 11:5490-5496. [PMID: 32584044 DOI: 10.1021/acs.jpclett.0c01247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Solid-state excitonic excitations play an increasingly important role in optoelectronic and light harvesting processes due to their ubiquitous presence in dipolar two-dimensional materials. Here we show that long-lived solid-state excitons induce chemical reactions in adsorbed molecules and thus convert light into chemical energy. For the model system (NO)2 dimer adsorbed on ordered c(4×4) C60 films, time-of-flight measurements following UV laser excitation reveal a slow and a fast dissociative desorption channel, which are assigned to intersystem crossing and internal conversion, respectively, by time-dependent density functional theory calculations.
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Affiliation(s)
- Christian Schwermann
- Institute of Solid State Theory and Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Steffen Linden
- Institute of Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Nikos L Doltsinis
- Institute of Solid State Theory and Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Helmut Zacharias
- Institute of Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
- Center for Soft Nanoscience, Westfälische Wilhelms-Universität, Busso-Peus-Straße 10, 48149 Münster, Germany
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8
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Alducin M, Camillone N, Hong SY, Juaristi JI. Electrons and Phonons Cooperate in the Laser-Induced Desorption of CO from Pd(111). PHYSICAL REVIEW LETTERS 2019; 123:246802. [PMID: 31922860 DOI: 10.1103/physrevlett.123.246802] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Indexed: 06/10/2023]
Abstract
Femtosecond laser induced desorption of CO from a CO-covered Pd(111) surface is investigated with ab initio molecular dynamics with electronic friction that incorporates effects due to the excited electronic and phononic systems, as well as out-of-phase coadsorbate interactions. Our simulations show evidence of an important electron-phonon synergy in promoting CO desorption that has largely been neglected in other similar systems. At the saturated coverage of 0.75 ML, effects due to CO-CO interadsorbate energy exchange are also important. Our dynamics simulations, in concert with site-specific desorption energy calculations, allow us to understand the large coverage dependence of the desorption yields observed in experiments.
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Affiliation(s)
- Maite Alducin
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Nicholas Camillone
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Sung-Young Hong
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - J Iñaki Juaristi
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
- Departamento de Física de Materiales, Facultad de Químicas (UPV/EHU), Apartado 1072, 20080 Donostia-San Sebastián, Spain
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9
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Ultrafast Vibrational Dynamics of CO Ligands on RuTPP/Cu(110) under Photodesorption Conditions. SURFACES 2019. [DOI: 10.3390/surfaces2010010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have studied CO coordinated to ruthenium tetraphenylporphyrin (RuTPP)/Cu(110) and directly adsorbed to Cu(110), using femtosecond pump-sum frequency probe spectroscopy, to alter the degree of electron-vibration coupling between the metal substrate and CO. We observe the facile femtosecond laser-induced desorption of CO from RuTPP/Cu(110), but not from Cu(110). A change in the vibrational transients, in the first few picoseconds, from a red- to blue-shift of the C–O stretching vibration under photodesorption conditions, was also observed. This drastic change can be explained, if the cause of the C–O frequency redshift of Cu(110) is not the usually-assumed anharmonic coupling to low frequency vibrational modes, but a charge transfer from hot electrons to the CO 2π* state. This antibonding state shifts to higher energies on RuTPP, removing the C–O redshift and, instead, reveals a blueshift, predicted to arise from electron-mediated coupling between the coherently excited internal stretch and low frequency modes in the system.
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10
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Wang L, Sagaguchi T, Okuhata T, Tsuboi M, Tamai N. Electron and Phonon Dynamics in Hexagonal Pd Nanosheets and Ag/Pd/Ag Sandwich Nanoplates. ACS NANO 2017; 11:1180-1188. [PMID: 28036162 DOI: 10.1021/acsnano.6b07082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Pd and its hybrid nanostructures have attracted considerable attention over the past decade, with both catalytic and plasmonic properties. The electron and phonon properties directly govern conversion efficiencies in applications such as energy collectors and photocatalysts. We report the dynamic processes of electron-phonon coupling and coherent acoustic phonon vibration in hexagonal Pd nanosheets and Ag/Pd/Ag sandwich nanoplates using transient absorption spectroscopy. The electron-phonon coupling constant of Pd nanosheets, GPd-nanosheet (8.7 × 1017 W/(m3·K)) is larger than that of the bulk GPd (5.0 × 1017 W/(m3·K)). The effective coupling constant Geff of Ag/Pd/Ag nanoplates decreases with increasing Ag shell thickness, finally approaching the bulk GAg. The variation of Geff is explained in terms of reduced density of states near Fermi level of Pd nanosheets with 1.8 nm ultrathin thickness. Coherent acoustic phonon vibration in Pd nanosheets is assigned to a fundamental breathing mode, similar to the vibration of benzene. The period increases with increasing Ag shell thickness. For Ag/Pd/Ag nanoplates with 20 nm thick Ag shells, the vibrational mode is ascribed to a quasi-extensional mode. The results show that the modes of the coherent acoustic phonon vibration transform with the geometric variation of Pd nanosheets and Ag/Pd/Ag nanoplates. Our results represent an understanding of quantum-confinement related electron dynamics and bulk-like phonon kinetics in the ultrathin Pd nanosheets and their hybrid nanostructures.
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Affiliation(s)
- Li Wang
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Takuya Sagaguchi
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Tomoki Okuhata
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Motohiro Tsuboi
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Naoto Tamai
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
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