1
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Kozakov AT, Skriabin AA, Kumar N. A simple equation to determine the shell thicknesses of core-shell nanoparticles based on XPS data of their elemental composition. Phys Chem Chem Phys 2023; 25:26820-26832. [PMID: 37782114 DOI: 10.1039/d3cp03140c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
A simple analytical expression is obtained relating the radius of the core, the thickness of the shell of nanoparticles, and the intensities of X-ray photoelectron lines from the core and shell, recorded during one experiment. The effective evaluation of the proposed equation was verified by comparison with the results of calculations of the parameters of core-shell nanoparticles (NPs) using known methods, as well as by comparing the results of ratios between the radius and thickness of the shell of specific NPs and their evaluations using the transmission electron microscopy method. The formula proposed in this work also allows using EDS data to estimate the core-shell parameters of nanoparticles. It is shown that the equation obtained in this work is not inferior to the solutions of the already existing approximate equations in terms of the accuracy of the determined parameters, but it is more convenient to use, since the data of one experiment are sufficient for its application. A simple approach to determine the thickness of a shell of NPs based on information about the elemental composition of the core-shell of NPs measured by X-ray photoelectron spectroscopy is developed.
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Affiliation(s)
- Alexey T Kozakov
- Research Institute of Physics, Southern Federal University, Stachki Ave. 194, Rostov-on-Don 344090, Russia.
| | - Anton A Skriabin
- Research Institute of Physics, Southern Federal University, Stachki Ave. 194, Rostov-on-Don 344090, Russia.
| | - Niranjan Kumar
- Rzhanov Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090, Russia
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2
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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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3
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Radnik J, Knigge X, Andresen E, Resch-Genger U, Cant DJH, Shard AG, Clifford CA. Composition, thickness, and homogeneity of the coating of core-shell nanoparticles-possibilities, limits, and challenges of X-ray photoelectron spectroscopy. Anal Bioanal Chem 2022; 414:4331-4345. [PMID: 35471249 PMCID: PMC9142455 DOI: 10.1007/s00216-022-04057-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/12/2022] [Accepted: 04/01/2022] [Indexed: 12/15/2022]
Abstract
Core–shell nanoparticles have attracted much attention in recent years due to their unique properties and their increasing importance in many technological and consumer products. However, the chemistry of nanoparticles is still rarely investigated in comparison to their size and morphology. In this review, the possibilities, limits, and challenges of X-ray photoelectron spectroscopy (XPS) for obtaining more insights into the composition, thickness, and homogeneity of nanoparticle coatings are discussed with four examples: CdSe/CdS quantum dots with a thick coating and a small core; NaYF4-based upconverting nanoparticles with a large Yb-doped core and a thin Er-doped coating; and two types of polymer nanoparticles with a poly(tetrafluoroethylene) core with either a poly(methyl methacrylate) or polystyrene coating. Different approaches for calculating the thickness of the coating are presented, like a simple numerical modelling or a more complex simulation of the photoelectron peaks. Additionally, modelling of the XPS background for the investigation of coating is discussed. Furthermore, the new possibilities to measure with varying excitation energies or with hard-energy X-ray sources (hard-energy X-ray photoelectron spectroscopy) are described. A discussion about the sources of uncertainty for the determination of the thickness of the coating completes this review. Graphical abstract ![]()
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Affiliation(s)
- Jörg Radnik
- Bundesanstalt für Materialforschung Und -Prüfung (BAM), Division 6.1 "Surface Analysis and Interfacial Chemistry", Unter den Eichen 44-46, 12203, Berlin, Germany.
| | - Xenia Knigge
- Bundesanstalt für Materialforschung Und -Prüfung (BAM), Division 6.1 "Surface Analysis and Interfacial Chemistry", Unter den Eichen 44-46, 12203, Berlin, Germany
| | - Elina Andresen
- Bundesanstalt für Materialforschung und -Prüfung (BAM), Division 1.2 "Biophotonics", Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - Ute Resch-Genger
- Bundesanstalt für Materialforschung und -Prüfung (BAM), Division 1.2 "Biophotonics", Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - David J H Cant
- National Physical Laboratory, Surface Technology Group, Hampton Road, Teddington, TW11 0LW, UK
| | - Alex G Shard
- National Physical Laboratory, Surface Technology Group, Hampton Road, Teddington, TW11 0LW, UK
| | - Charles A Clifford
- National Physical Laboratory, Surface Technology Group, Hampton Road, Teddington, TW11 0LW, UK
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4
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Chang KP, Yeh YC, Wu CJ, Yen CC, Wuu DS. Improved Characteristics of CdSe/CdS/ZnS Core-Shell Quantum Dots Using an Oleylamine-Modified Process. NANOMATERIALS 2022; 12:nano12060909. [PMID: 35335721 PMCID: PMC8950307 DOI: 10.3390/nano12060909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/05/2022] [Accepted: 03/07/2022] [Indexed: 01/03/2023]
Abstract
CdSe/CdS with ZnS/ZnO shell quantum dots (QDs) are synthesized by a one-pot method with various oleylamine (OLA) contents. The crystal structures of the QDs were analyzed by X-ray diffractometry, which showed ZnS diffraction peaks. It was represented that the ZnS shell was formed on the surface of the CdSe/CdS core. Interestingly, QDs with a high OLA concentration exhibit diffraction peaks of ZnS/ZnO. As a result, the thermal stability of QDs with ZnS/ZnO shells exhibits better performance than those with ZnS shells. In addition, the photoluminescence intensity of QDs with ZnS/ZnO shells shows a relatively slow decay of 7.1% compared with ZnS shells at 85 °C/85% relative humidity aging test for 500 h. These indicate that QDs with different OLA modifications can form ZnS/ZnO shells and have good stability in a harsh environment. The emission wavelength of QDs can be tuned from 505 to 610 nm, suitable for micro-LED display applications.
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Affiliation(s)
- Kai-Ping Chang
- Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (K.-P.C.); (Y.-C.Y.); (C.-J.W.); (C.-C.Y.)
| | - Yu-Cheng Yeh
- Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (K.-P.C.); (Y.-C.Y.); (C.-J.W.); (C.-C.Y.)
| | - Chung-Jui Wu
- Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (K.-P.C.); (Y.-C.Y.); (C.-J.W.); (C.-C.Y.)
| | - Chao-Chun Yen
- Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (K.-P.C.); (Y.-C.Y.); (C.-J.W.); (C.-C.Y.)
| | - Dong-Sing Wuu
- Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (K.-P.C.); (Y.-C.Y.); (C.-J.W.); (C.-C.Y.)
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 40227, Taiwan
- Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, Nantou 54561, Taiwan
- Correspondence: ; Tel.: +886-49-2910960 (ext. 2000)
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Spencer BF, Church SA, Thompson P, Cant DJH, Maniyarasu S, Theodosiou A, Jones AN, Kappers MJ, Binks DJ, Oliver RA, Higgins J, Thomas AG, Thomson T, Shard AG, Flavell WR. Characterization of buried interfaces using Ga Kα hard X-ray photoelectron spectroscopy (HAXPES). Faraday Discuss 2022; 236:311-337. [DOI: 10.1039/d2fd00021k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
HAXPES enables the detection of buried interfaces with an increased photo electron sampling depth.
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Affiliation(s)
- B. F. Spencer
- Henry Royce Institute, Photon Science Institute, Department of Materials, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - S. A. Church
- Henry Royce Institute, Photon Science Institute, Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - P. Thompson
- Department of Computer Science, School of Engineering, The University of Manchester, Manchester, M13 9PL, UK
| | - D. J. H. Cant
- Surface Technologies, Chemical and Biological Sciences Department, National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | - S. Maniyarasu
- Henry Royce Institute, Photon Science Institute, Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - A. Theodosiou
- The Nuclear Graphite Research Group, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - A. N. Jones
- The Nuclear Graphite Research Group, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - M. J. Kappers
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
| | - D. J. Binks
- Henry Royce Institute, Photon Science Institute, Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - R. A. Oliver
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
| | | | - A. G. Thomas
- Henry Royce Institute, Photon Science Institute, Department of Materials, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - T. Thomson
- Department of Computer Science, School of Engineering, The University of Manchester, Manchester, M13 9PL, UK
| | - A. G. Shard
- Surface Technologies, Chemical and Biological Sciences Department, National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | - W. R. Flavell
- Henry Royce Institute, Photon Science Institute, Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK
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6
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Geißler D, Nirmalananthan-Budau N, Scholtz L, Tavernaro I, Resch-Genger U. Analyzing the surface of functional nanomaterials-how to quantify the total and derivatizable number of functional groups and ligands. Mikrochim Acta 2021; 188:321. [PMID: 34482449 PMCID: PMC8418596 DOI: 10.1007/s00604-021-04960-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/08/2021] [Indexed: 12/04/2022]
Abstract
Functional nanomaterials (NM) of different size, shape, chemical composition, and surface chemistry are of increasing relevance for many key technologies of the twenty-first century. This includes polymer and silica or silica-coated nanoparticles (NP) with covalently bound surface groups, semiconductor quantum dots (QD), metal and metal oxide NP, and lanthanide-based NP with coordinatively or electrostatically bound ligands, as well as surface-coated nanostructures like micellar encapsulated NP. The surface chemistry can significantly affect the physicochemical properties of NM, their charge, their processability and performance, as well as their impact on human health and the environment. Thus, analytical methods for the characterization of NM surface chemistry regarding chemical identification, quantification, and accessibility of functional groups (FG) and surface ligands bearing such FG are of increasing importance for quality control of NM synthesis up to nanosafety. Here, we provide an overview of analytical methods for FG analysis and quantification with special emphasis on bioanalytically relevant FG broadly utilized for the covalent attachment of biomolecules like proteins, peptides, and oligonucleotides and address method- and material-related challenges and limitations. Analytical techniques reviewed include electrochemical titration methods, optical assays, nuclear magnetic resonance and vibrational spectroscopy, as well as X-ray based and thermal analysis methods, covering the last 5-10 years. Criteria for method classification and evaluation include the need for a signal-generating label, provision of either the total or derivatizable number of FG, need for expensive instrumentation, and suitability for process and production control during NM synthesis and functionalization.
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Affiliation(s)
- Daniel Geißler
- Bundesanstalt für Materialforschung und -prüfung (BAM), Division Biophotonics (BAM-1.2), Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - Nithiya Nirmalananthan-Budau
- Bundesanstalt für Materialforschung und -prüfung (BAM), Division Biophotonics (BAM-1.2), Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - Lena Scholtz
- Bundesanstalt für Materialforschung und -prüfung (BAM), Division Biophotonics (BAM-1.2), Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - Isabella Tavernaro
- Bundesanstalt für Materialforschung und -prüfung (BAM), Division Biophotonics (BAM-1.2), Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - Ute Resch-Genger
- Bundesanstalt für Materialforschung und -prüfung (BAM), Division Biophotonics (BAM-1.2), Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
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7
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Cant DJH, Müller A, Clifford CA, Unger WES, Shard AG. Summary of ISO/TC 201 Technical Report 23173—Surface chemical analysis—Electron spectroscopies—Measurement of the thickness and composition of nanoparticle coatings. SURF INTERFACE ANAL 2021. [DOI: 10.1002/sia.6987] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- David J. H. Cant
- Chemical and Biological Sciences National Physical Laboratory (NPL) Teddington UK
| | - Anja Müller
- Division 6.1 Surface Analysis and Interfacial Chemistry Bundesanstalt für Materialforschung und‐prüfung (BAM) Berlin Germany
| | - Charles A. Clifford
- Chemical and Biological Sciences National Physical Laboratory (NPL) Teddington UK
| | - Wolfgang E. S. Unger
- Division 6.1 Surface Analysis and Interfacial Chemistry Bundesanstalt für Materialforschung und‐prüfung (BAM) Berlin Germany
| | - Alexander G. Shard
- Chemical and Biological Sciences National Physical Laboratory (NPL) Teddington UK
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8
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Reliable Surface Analysis Data of Nanomaterials in Support of Risk Assessment Based on Minimum Information Requirements. NANOMATERIALS 2021; 11:nano11030639. [PMID: 33807515 PMCID: PMC8001671 DOI: 10.3390/nano11030639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/16/2021] [Accepted: 03/02/2021] [Indexed: 02/07/2023]
Abstract
The minimum information requirements needed to guarantee high-quality surface analysis data of nanomaterials are described with the aim to provide reliable and traceable information about size, shape, elemental composition and surface chemistry for risk assessment approaches. The widespread surface analysis methods electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were considered. The complete analysis sequence from sample preparation, over measurements, to data analysis and data format for reporting and archiving is outlined. All selected methods are used in surface analysis since many years so that many aspects of the analysis (including (meta)data formats) are already standardized. As a practical analysis use case, two coated TiO2 reference nanoparticulate samples, which are available on the Joint Research Centre (JRC) repository, were selected. The added value of the complementary analysis is highlighted based on the minimum information requirements, which are well-defined for the analysis methods selected. The present paper is supposed to serve primarily as a source of understanding of the high standardization level already available for the high-quality data in surface analysis of nanomaterials as reliable input for the nanosafety community.
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Müller A, Krahl T, Radnik J, Wagner A, Kreyenschulte C, Werner WS, Ritter B, Kemnitz E, Unger WE. Chemical in‐depth analysis of (Ca/Sr)F
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core–shell like nanoparticles by X‐ray photoelectron spectroscopy with tunable excitation energy. SURF INTERFACE ANAL 2021. [DOI: 10.1002/sia.6937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Anja Müller
- Department of Chemistry Humboldt‐Universität zu Berlin Berlin Germany
- Surface Analysis and Interfacial Chemistry Bundesanstalt für Materialforschung und ‐prüfung (BAM) Berlin Germany
| | - Thoralf Krahl
- Department of Chemistry Humboldt‐Universität zu Berlin Berlin Germany
| | - Jörg Radnik
- Surface Analysis and Interfacial Chemistry Bundesanstalt für Materialforschung und ‐prüfung (BAM) Berlin Germany
| | - Andreas Wagner
- Surface Analysis and Interfacial Chemistry Bundesanstalt für Materialforschung und ‐prüfung (BAM) Berlin Germany
| | | | | | - Benjamin Ritter
- Department of Chemistry Humboldt‐Universität zu Berlin Berlin Germany
| | - Erhard Kemnitz
- Department of Chemistry Humboldt‐Universität zu Berlin Berlin Germany
| | - Wolfgang E.S. Unger
- Department of Chemistry Humboldt‐Universität zu Berlin Berlin Germany
- Surface Analysis and Interfacial Chemistry Bundesanstalt für Materialforschung und ‐prüfung (BAM) Berlin Germany
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10
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Combining HR-TEM and XPS to elucidate the core-shell structure of ultrabright CdSe/CdS semiconductor quantum dots. Sci Rep 2020; 10:20712. [PMID: 33244030 PMCID: PMC7692488 DOI: 10.1038/s41598-020-77530-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/11/2020] [Indexed: 12/17/2022] Open
Abstract
Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the application-relevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties.
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11
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Salvat-Pujol F, Villarrubia JS. Conventional vs. model-based measurement of patterned line widths from scanning electron microscopy profiles. Ultramicroscopy 2019; 206:112819. [PMID: 31421625 PMCID: PMC6858966 DOI: 10.1016/j.ultramic.2019.112819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/26/2019] [Accepted: 07/29/2019] [Indexed: 11/28/2022]
Abstract
Scanning electron microscopy (SEM) is a practical tool to determine the dimensions of nanometer-scale features. Conventional width measurements use arbitrary criteria, e.g., a 50 % threshold crossing, to assign feature boundaries in the measured SEM intensity profile. To estimate the errors associated with such a procedure, we have simulated secondary electron signals from a suite of line shapes consisting of 30 nm tall silicon lines with varying width, sidewall angle, and corner rounding. Four different inelastic scattering models were employed in Monte Carlo simulations of electron transport to compute secondary electron image intensity profiles for each of the shapes. The 4 models were combinations of dielectric function theory with either the single-pole approximation (SPA) or the full Penn algorithm (FPA), and either with or without Auger electron emission. Feature widths were determined either by the conventional threshold method or by the model-based library (MBL) method, which is a fit of the simulated profiles to the reference model (FPA + Auger). On the basis of these comparisons we estimate the error in the measured width of such features by the conventional procedure to be as much as several nanometers. A 1 nm difference in the size of, e.g., a nominally 10 nm transistor gate would substantially alter its electronic properties. Thus, the conventional measurements do not meet the contemporary requirements of the semiconductor industry. In contrast, MBL measurements employing models with varying accuracy differed one from another by less than 1 nm. Thus, a MBL measurement is preferable in the nanoscale domain.
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Affiliation(s)
- Francesc Salvat-Pujol
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; CERN, Geneva 23 CH-1211, Switzerland
| | - John S Villarrubia
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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12
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Trindell JA, Duan Z, Henkelman G, Crooks RM. Well-Defined Nanoparticle Electrocatalysts for the Refinement of Theory. Chem Rev 2019; 120:814-850. [DOI: 10.1021/acs.chemrev.9b00246] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jamie A. Trindell
- Department of Chemistry and Texas Materials Institute, The University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - Zhiyao Duan
- Department of Chemistry and Texas Materials Institute, The University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - Graeme Henkelman
- Department of Chemistry and Texas Materials Institute, The University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - Richard M. Crooks
- Department of Chemistry and Texas Materials Institute, The University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
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Baer DR, Artyushkova K, Brundle CR, Castle JE, Engelhard MH, Gaskell KJ, Grant JT, Haasch RT, Linford MR, Powell CJ, Shard AG, Sherwood PMA, Smentkowski VS. Practical Guides for X-Ray Photoelectron Spectroscopy (XPS): First Steps in planning, conducting and reporting XPS measurements. JOURNAL OF VACUUM SCIENCE & TECHNOLOGY. A, VACUUM, SURFACES, AND FILMS : AN OFFICIAL JOURNAL OF THE AMERICAN VACUUM SOCIETY 2019; 37:10.1116/1.5065501. [PMID: 31579351 PMCID: PMC6774202 DOI: 10.1116/1.5065501] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Over the past three decades, the widespread utility and applicability of X-ray photoelectron spectroscopy (XPS) in research and applications has made it the most popular and widely used method of surface analysis. Associated with this increased use has been an increase in the number of new or inexperienced users which has led to erroneous uses and misapplications of the method. This article is the first in a series of guides assembled by a committee of experienced XPS practitioners that are intended to assist inexperienced users by providing information about good practices in the use of XPS. This first guide outlines steps appropriate for determining whether XPS is capable of obtaining the desired information, identifies issues relevant to planning, conducting and reporting an XPS measurement, and identifies sources of practical information for conducting XPS measurements. Many of the topics and questions addressed in this article also apply to other surface-analysis techniques.
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Affiliation(s)
- Donald R. Baer
- Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, P. O. Box 999, Richland, Washington 99352
| | | | | | - James E. Castle
- University of Surrey, Department of Mechanical Engineering Science, Guildford, Surrey, GU2 7XH, United Kingdom
| | - Mark H. Engelhard
- Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, P. O. Box 999, Richland Washington 99352
| | - Karen J. Gaskell
- University of Maryland, Department of Chemistry and Biochemistry, College Park, Maryland 20720
| | - John T. Grant
- Surface Analysis Consulting, Clearwater, Florida 33767
| | - Richard T. Haasch
- University of Illinois, Materials Research Laboratory, 104 S. Goodwin Ave, Urbana, Illinois 61801-2902
| | - Matthew R. Linford
- Brigham Young University, Department of Chemistry & Biochemistry, Provo, Utah 84602
| | - Cedric J. Powell
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-8370
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Baer DR, Karakoti AS, Clifford CA, Minelli C, Unger WES. Importance of sample preparation on reliable surface characterisation of nano-objects: ISO standard 20579-4. SURF INTERFACE ANAL 2018. [DOI: 10.1002/sia.6490] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Donald R. Baer
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory; Richland WA 99352 USA
| | - Ajay S. Karakoti
- School of Engineering and Applied Science and, Division of Biological and Life Sciences-School of Arts and Sciences; Ahmedabad University; Ahmedabad Gujarat 380009 India
| | - Charles A. Clifford
- Analytical Science, National Physical Laboratory; Teddington Middlesex TW11 0LW UK
| | - Caterina Minelli
- Analytical Science, National Physical Laboratory; Teddington Middlesex TW11 0LW UK
| | - Wolfgang E. S. Unger
- Surface Analysis and Interfacial Chemistry Division; Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen; 87 12205 Berlin Germany
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Baer DR. The Chameleon Effect: Characterization Challenges Due to the Variability of Nanoparticles and Their Surfaces. Front Chem 2018; 6:145. [PMID: 29868553 PMCID: PMC5949347 DOI: 10.3389/fchem.2018.00145] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/12/2018] [Indexed: 12/12/2022] Open
Abstract
Nanoparticles in a variety of forms are increasing important in fundamental research, technological and medical applications, and environmental or toxicology studies. Physical and chemical drivers that lead to multiple types of particle instabilities complicate both the ability to produce, appropriately characterize, and consistently deliver well-defined particles, frequently leading to inconsistencies, and conflicts in the published literature. This perspective suggests that provenance information, beyond that often recorded or reported, and application of a set of core characterization methods, including a surface sensitive technique, consistently applied at critical times can serve as tools in the effort minimize reproducibility issues.
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Affiliation(s)
- Donald R. Baer
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, United States
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