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Gong JM, Khan MSS, Da B, Yoshikawa H, Tanuma S, Ding ZJ. A theoretical characterization method for non-spherical core-shell nanoparticles by XPS. Phys Chem Chem Phys 2023; 25:20917-20932. [PMID: 37492028 DOI: 10.1039/d3cp01413d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Core-shell nanoparticles (NPs) are active research areas for their unique properties and wide applications. By changing the elemental composition in the core and shell, a series of core-shell NPs with specific functions can be obtained, where the sizes of the core and shell also influence the properties. X-ray photoelectron spectroscopy (XPS) is useful in this context as a means of quantitatively analyzing such NPs. The empirical formula proposed by Shard [J. Phys. Chem. C, 2012, 116(31), 16806-16813] for calculating the shell thickness of the spherical core-shell NPs has been verified by Powell et al. [J. Phys. Chem. C, 2016, 120(39), 22730-22738] through a simulation of XPS with Simulation of Electron Spectra for Surface Analysis (SESSA) software. However, real core-shell NPs are not necessarily ideal spheres; such NPs can have rich shapes and uneven thicknesses. This work aims to extend the Shard formula to non-ideal core-shell NPs. We have used a Monte Carlo simulation method to study the XPS signal variation with the shell thickness for several modeled non-spherical shapes of core-shell NPs including some complex geometric structures which are numerically constructed with finite-element triangular meshes. Five types of non-spherical shapes, i.e. egg, ellipsoid, rod, rough-surface, and star shapes, are considered, while the size parameters are varied over a wide range. The equivalent radius and equivalent thickness are defined to characterize the average size of the nanoparticles for the use of the Shard formula. We have thus derived an extended Shard formula for the specific core-shell NPs, with which the relative error between the predicted shell thickness and the real thickness can be reduced to less than 10%.
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Affiliation(s)
- J M Gong
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China.
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
- Materials Data Platform Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - M S S Khan
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
| | - B Da
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - H Yoshikawa
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - S Tanuma
- Materials Data Platform Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Z J Ding
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China.
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
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Li Z, Gong JM, Da B, Tóth J, Tőkési K, Zeng RG, Ding ZJ. Improved reverse Monte Carlo analysis of optical property of Fe and Ni from reflection electron energy loss spectroscopy spectra. Sci Rep 2023; 13:12480. [PMID: 37528114 PMCID: PMC10393999 DOI: 10.1038/s41598-023-38769-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 07/14/2023] [Indexed: 08/03/2023] Open
Abstract
The energy loss functions (ELFs) of Fe and Ni have been derived from measured reflection electron energy loss spectroscopy (REELS) spectra by a reverse Monte Carlo analysis in our previous work. In this work, we present further improvements of ELFs for these metals. For Fe, we have updated ELFs at primary electron energies of 2 keV and 3 keV in a wider photon energy region (0-180 eV) with a better accuracy, which is verified by sum rules. Regarding to Ni, we supplement the ELF at primary energy of 5 keV and we also improve the data accuracy at 3 keV. Applying these new and more accurate ELFs we present the optical constants and dielectric functions for the two metals. The improvements were highlighted by comparing our present results with the previous data.
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Affiliation(s)
- Z Li
- Department of Physics, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China
| | - J M Gong
- Department of Physics, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China
| | - B Da
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - J Tóth
- Institute for Nuclear Research, P.O. Box 51, Debrecen, Hungary
| | - K Tőkési
- Institute for Nuclear Research, P.O. Box 51, Debrecen, Hungary.
| | - R G Zeng
- Institute of Materials, China Academy of Engineering Physics, P.O. Box 9071, Jiangyou, 621907, Sichuan, People's Republic of China
| | - Z J Ding
- Department of Physics, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China.
- Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China.
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Liu X, Lu D, Hou Z, Nagata K, Da B, Yoshikawa H, Tanuma S, Sun Y, Ding Z. Establishment and validation of an electron inelastic mean free path database for narrow bandgap inorganic compounds with a machine learning approach. Phys Chem Chem Phys 2023. [PMID: 37376953 DOI: 10.1039/d2cp04393a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Narrow bandgap inorganic compounds are extremely important in many areas of physics. However, their basic parameter database for surface analysis is incomplete. Electron inelastic mean free paths (IMFPs) are important parameters in surface analysis methods, such as electron spectroscopy and electron microscopy. Our previous research has presented a machine learning (ML) method to describe and predict IMFPs from calculated IMFPs for 41 elemental solids. This paper extends the use of the same machine learning method to 42 inorganic compounds based on the experience in predicting elemental electron IMFPs. The in-depth discussion extends to including material dependence discussion and parameter value selections. After robust validation of the ML method, we have produced an extensive IMFP database for 12 039 narrow bandgap inorganic compounds. Our findings suggest that ML is very efficient and powerful for IMFP description and database completion for various materials and has many advantages, including stability and convenience, over traditional methods.
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Affiliation(s)
- Xun Liu
- Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - Dabao Lu
- Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - Zhufeng Hou
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Kenji Nagata
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - Bo Da
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - Hideki Yoshikawa
- Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
| | - Shigeo Tanuma
- Research Network and Facility Services Division, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
| | - Yang Sun
- Department of Physics, Xiamen University, Xiamen, Fujian 361-005, China
| | - Zejun Ding
- Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
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Yang TF, Zeng RG, Yang LH, Sulyok A, Menyhárd M, Tőkési K, Ding ZJ. Energy loss function of samarium. Sci Rep 2023; 13:3909. [PMID: 36890188 PMCID: PMC9995327 DOI: 10.1038/s41598-023-30770-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 02/28/2023] [Indexed: 03/10/2023] Open
Abstract
We present a combined experimental and theoretical work to obtain the energy loss function (ELF) or the excitation spectrum of samarium in the energy loss range between 3 and 200 eV. At low loss energies, the plasmon excitation is clearly identified and the surface and bulk contributions are distinguished. For the precise analysis the frequency-dependent energy loss function and the related optical constants (n and k) of samarium were extracted from the measured reflection electron energy loss spectroscopy (REELS) spectra by the reverse Monte Carlo method. The ps- and f-sum rules with final ELF fulfils the nominal values with 0.2% and 2.5% accuracy, respectively. It was found that a bulk mode locates at 14.2 eV with the peak width ~6 eV and the corresponding broaden surface plasmon mode locates at energies of 5-11 eV.
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Affiliation(s)
- T F Yang
- Department of Physics, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China
| | - R G Zeng
- Institute of Materials, China Academy of Engineering Physics, P.O. Box 9071, Jiangyou, 621907, Sichuan, People's Republic of China
| | - L H Yang
- Department of Physics, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China
| | - A Sulyok
- Centre for Energy Research, Research Institute for Technical Physics and Materials Science, ELKH, P.O. Box 49, H-1525, Budapest, Hungary
| | - M Menyhárd
- Centre for Energy Research, Research Institute for Technical Physics and Materials Science, ELKH, P.O. Box 49, H-1525, Budapest, Hungary
| | - K Tőkési
- Institute for Nuclear Research, ELKH, P.O. Box 51, Debrecen, Hungary.
| | - Z J Ding
- Department of Physics, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China. .,Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China.
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