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2. New challenges associated with hard X‐ray photoelectron spectroscopy (report on the 2023 ASTM E42‐ASSD AVS workshop)

Author

Herrera‐Gomez, Alberto, Cant, David J. H., Conard, Thierry, Renault, Olivier, Linford, Matthew R., Pinder, Joshua W., Fenton, Jeff, and Baer, Donald R.

Subjects
*X-ray photoelectron spectroscopy, *HARD X-rays
Abstract

In contrast to traditional X‐ray photoelectron spectroscopy (XPS), hard X‐ray photoelectron spectroscopy (HAXPES) can provide information from deeper within a sample while maintaining chemical resolution. However, working with higher energy X‐rays introduces a series of new or different issues ranging from energy calibration to factors associated with quantitative analysis. As part of the efforts to identify and increase community awareness about these issues, a workshop was held to review HAXPES metrology challenges with the perspective of converting it into a quantitative technique. A summary is hereby given of this workshop, which was entitled “What New Challenges Come with the Capabilities of HAXPES?” It was held in Portland, OR, USA, on November 7, 2023, and was primarily sponsored by the ASTM E42 Committee and the Applied Surface Science Division of the American Vacuum Society. This report contains summaries of the presentations and discussions at this workshop regarding the current open problems in HAXPES metrology. There were 20 participants at the workshop. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Quantitative and Qualitative Analyses of Mass Spectra of OEL Materials by Artificial Neural Network and Interface Evaluation: Results from a VAMAS Interlaboratory Study

Author

Aoyagi, Satoka, primary, Cant, David J. H., additional, Dürr, Michael, additional, Eyres, Anya, additional, Fearn, Sarah, additional, Gilmore, Ian S., additional, Iida, Shin-ichi, additional, Ikeda, Reiko, additional, Ishikawa, Kazutaka, additional, Lagator, Matija, additional, Lockyer, Nicholas, additional, Keller, Philip, additional, Matsuda, Kazuhiro, additional, Murayama, Yohei, additional, Okamoto, Masayuki, additional, Reed, Benjamen P., additional, Shard, Alexander G., additional, Takano, Akio, additional, Trindade, Gustavo F., additional, and Vorng, Jean-Luc, additional

Published
2023
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6. Magic angle HAXPES

Author

Cant, David J. H., Reed, Benjamen P., Spencer, Ben S., Flavell, Wendy R., and Shard, Alexander G.

Subjects
Radiation, Physical and Theoretical Chemistry, Condensed Matter Physics, Spectroscopy, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials
Abstract

The use of higher energy X-ray sources for photoelectron spectroscopy is receiving considerable attention due to the increased availability of laboratory-based instrumentation and an improved insight into the structures and interfacial properties of technological materials. In traditional X-ray photoelectron spectroscopy the design of the instrument often compensates for anisotropy in photoelectron emission through consideration of the angles between the X-ray source and the electron analyser. X-ray polarisation and non-dipole effects in photoemission are usually assumed to be negligible. However, for high energy XPS (HAXPES) both may be significant. Polarisation at synchrotron sources is an important consideration and non-dipole effects are generally more significant at higher photon energies. In this article we demonstrate that, for certain polarisations, ‘magic angle’ geometries exist that minimise the effects of both dipole and non-dipole contributions in photoemission. However, it is not possible to find such geometries for unpolarised X-rays; achieving a ‘magic angle’ geometry in HAXPES requires the X-rays to have a degree of linear polarisation of 1/3 or greater.

Published
2023

10. ERRATUM: “Versailles project on advanced materials and standards interlaboratory study on intensity calibration for x-ray photoelectron spectroscopy instruments using low-density polyethylene” [J. Vac. Sci. Technol. A 38, 063208 (2020)]

Author

Reed, Benjamen P., primary, Cant, David J. H., additional, Spencer, Steve J., additional, Carmona-Carmona, Abraham Jorge, additional, Bushell, Adam, additional, Herrera-Gómez, Alberto, additional, Kurokawa, Akira, additional, Thissen, Andreas, additional, Thomas, Andrew G., additional, Britton, Andrew J., additional, Bernasik, Andrzej, additional, Fuchs, Anne, additional, Baddorf, Arthur P., additional, Bock, Bernd, additional, Theilacker, Bill, additional, Cheng, Bin, additional, Castner, David G., additional, Morgan, David J., additional, Valley, David, additional, Willneff, Elizabeth A., additional, Smith, Emily F., additional, Nolot, Emmanuel, additional, Xie, Fangyan, additional, Zorn, Gilad, additional, Smith, Graham C., additional, Yasufuku, Hideyuki, additional, Fenton, Jeffrey L., additional, Chen, Jian, additional, Counsell, Jonathan D. P., additional, Radnik, Jörg, additional, Gaskell, Karen J., additional, Artyushkova, Kateryna, additional, Yang, Li, additional, Zhang, Lulu, additional, Eguchi, Makiho, additional, Walker, Marc, additional, Hajdyła, Mariusz, additional, Marzec, Mateusz M., additional, Linford, Matthew R., additional, Kubota, Naoyoshi, additional, Cortazar-Martínez, Orlando, additional, Dietrich, Paul, additional, Satoh, Riki, additional, Schroeder, Sven L. M., additional, Avval, Tahereh G., additional, Nagatomi, Takaharu, additional, Fernandez, Vincent, additional, Lake, Wayne, additional, Azuma, Yasushi, additional, Yoshikawa, Yusuke, additional, Compean-Gonzalez, Claudia L., additional, Ceccone, Giacomo, additional, and Shard, Alexander G., additional

Published
2021
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11. Versailles Project on Advanced Materials and Standards interlaboratory study on intensity calibration for x-ray photoelectron spectroscopy instruments using low-density polyethylene

Author

Reed, Benjamen P., primary, Cant, David J. H., additional, Spencer, Steve J., additional, Carmona-Carmona, Abraham Jorge, additional, Bushell, Adam, additional, Herrera-Gómez, Alberto, additional, Kurokawa, Akira, additional, Thissen, Andreas, additional, Thomas, Andrew G., additional, Britton, Andrew J., additional, Bernasik, Andrzej, additional, Fuchs, Anne, additional, Baddorf, Arthur P., additional, Bock, Bernd, additional, Theilacker, Bill, additional, Cheng, Bin, additional, Castner, David G., additional, Morgan, David J., additional, Valley, David, additional, Willneff, Elizabeth A., additional, Smith, Emily F., additional, Nolot, Emmanuel, additional, Xie, Fangyan, additional, Zorn, Gilad, additional, Smith, Graham C., additional, Yasufuku, Hideyuki, additional, Fenton, Jeffery L., additional, Chen, Jian, additional, Counsell, Jonathan D. P., additional, Radnik, Jörg, additional, Gaskell, Karen J., additional, Artyushkova, Kateryna, additional, Yang, Li, additional, Zhang, Lulu, additional, Eguchi, Makiho, additional, Walker, Marc, additional, Hajdyła, Mariusz, additional, Marzec, Mateusz M., additional, Linford, Matthew R., additional, Kubota, Naoyoshi, additional, Cortazar-Martínez, Orlando, additional, Dietrich, Paul, additional, Satoh, Riki, additional, Schroeder, Sven L. M., additional, Avval, Tahereh G., additional, Nagatomi, Takaharu, additional, Fernandez, Vincent, additional, Lake, Wayne, additional, Azuma, Yasushi, additional, Yoshikawa, Yusuke, additional, and Shard, Alexander G., additional

Published
2020
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14. Exposure of mass-selected bimetallic Pt–Ti nanoalloys to oxygen explored using scanning transmission electron microscopy and density functional theory

Author

Gholhaki, Saeed, Hung, Shih-Hsuan, Cant, David J. H., Blackmore, Caroline E., Shard, Alex G., Guo, Quanmin, McKenna, Keith P., and Palmer, Richard E.

Abstract

The response of nanoparticles to exposure to ambient conditions and especially oxidation is fundamental to the application of nanotechnology. Bimetallic platinum–titanium nanoparticles of selected mass, 30 kDa and 90 kDa, were produced using a magnetron sputtering gas condensation cluster source and deposited onto amorphous carbon TEM grids. The nanoparticles were analysed with a Cs-corrected Scanning Transmission Electron Microscope (STEM) in High Angle Annular Dark Field (HAADF) mode. It was observed that prior to full Ti oxidation, Pt atoms were dispersed within a Ti shell. However, after full oxidation by prolonged exposure to ambient conditions prior to STEM, the smaller size 30 kDa particles form a single Pt core and the larger size 90 kDa particles exhibit a multi-core structure. Electron beam annealing induced a single core morphology in the larger particles. First principles density functional theory (DFT) calculations were employed to calculate the lowest energy structure of the Pt–Ti nanoparticles with and without the presence of oxygen. It was demonstrated that, as the concentration of oxygen increases, the lowest energy structure changes from dispersed Pt to multiple Pt cores and finally a single Pt core, which is in good agreement with the experimental observations.

Published
2018

16. A Technique for Calculation of Shell Thicknesses for Core-Shell-Shell Nanoparticles from XPS Data

Author

Cant, David J. H., Wang, Yung-Chen, Castner, David G., and Shard, Alexander G.

Subjects
Nuclear Theory, Physics::Atomic and Molecular Clusters, Article
Abstract

This paper extends a straightforward technique for the calculation of shell thicknesses in core-shell nanoparticles to the case of core-shell-shell nanoparticles using X-ray Photoelectron Spectroscopy (XPS) data. This method can be applied by XPS analysts and does not require any numerical simulation or advanced knowledge, although iteration is required in the case where both shell thicknesses are unknown. The standard deviation in the calculated thicknesses vs simulated values is typically less than 10%, which is the uncertainty of the electron attenuation lengths used in XPS analysis.

Published
2016

17. Surface properties of nanocrystalline PbS films deposited at the water-oil interface: A study of atmospheric aging

Author

Cant, David J H, Syres, Karen L., Lunt, Patrick J B, Radtke, Hanna, Treacy, Jon P W, Thomas, Patsy John, Lewis, Edward A., Haigh, Sarah J., Obrien, Paul, Schulte, Karina, Bondino, Federica, Magnano, Elena, and Flavell, Wendy R.

Subjects
Surface properties of nanocrystalline PbS films deposited at the water-oil interface: A study of atmospheric aging
Abstract

Nanocrystalline thin films of PbS are obtained in a straightforward reaction by precipitation at the interface between toluene (containing a Pb precursor) and water (containing Na2S). Lead thiobiuret [Pb(SON(CNiPr2)2)2] and lead diethyldithiocarbamate [Pb(S2CNEt2)2] precursors are used. The films are characterized by X-ray diffraction and electron microscopy, revealing typical particle sizes of 10-40 nm and preferred (200) orientation. Synchrotron-excited depth-profiling X-ray photoelectron spectroscopy (XPS) is used to determine the depth-dependent chemical composition as a function of surface aging in air for periods of up to 9 months. The as-synthesized films show a 1:1 Pb/S composition. Initial degradation occurs to form lead hydroxide and small quantities of surface-adsorbed -SH species. A lead-deficient Pb1-xS phase is produced as the aging proceeds. Oxidation of the sulfur occurs later to form sulfite and sulfate products that are highly localized at the surface layers of the nanocrystals. These species show logarithmic growth kinetics, demonstrating that the sulfite/sulfate layer acts to passivate the nanocrystals. Our results demonstrate that the initial reaction of the PbS nanocrystals (forming lead hydroxide) is incongruent. The results are discussed in the context of the use of PbS nanocrystals as light-harvesting elements in next-generation solar technology.

Published
2015
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18. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS

Author

Belsey, Natalie A., primary, Cant, David J. H., additional, Minelli, Caterina, additional, Araujo, Joyce R., additional, Bock, Bernd, additional, Brüner, Philipp, additional, Castner, David G., additional, Ceccone, Giacomo, additional, Counsell, Jonathan D. P., additional, Dietrich, Paul M., additional, Engelhard, Mark H., additional, Fearn, Sarah, additional, Galhardo, Carlos E., additional, Kalbe, Henryk, additional, Kim, Jeong Won, additional, Lartundo-Rojas, Luis, additional, Luftman, Henry S., additional, Nunney, Tim S., additional, Pseiner, Johannes, additional, Smith, Emily F., additional, Spampinato, Valentina, additional, Sturm, Jacobus M., additional, Thomas, Andrew G., additional, Treacy, Jon P.W., additional, Veith, Lothar, additional, Wagstaffe, Michael, additional, Wang, Hai, additional, Wang, Meiling, additional, Wang, Yung-Chen, additional, Werner, Wolfgang, additional, Yang, Li, additional, and Shard, Alexander G., additional

Published
2016
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20. Surface Properties of Nanocrystalline PbS Films Deposited at the Water–Oil Interface: A Study of Atmospheric Aging

Author

Cant, David J. H., primary, Syres, Karen L., additional, Lunt, Patrick J. B., additional, Radtke, Hanna, additional, Treacy, Jon, additional, Thomas, P. John, additional, Lewis, Edward A., additional, Haigh, Sarah J., additional, O’Brien, Paul, additional, Schulte, Karina, additional, Bondino, Federica, additional, Magnano, Elena, additional, and Flavell, Wendy R., additional

Published
2015
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21. Growth of nanocrystalline thin films of metal sulfides [CdS, ZnS, CuS and PbS] at the water–oil interface

Author

Thomas, P. John, primary, Stansfield, Gemma L., additional, Komba, Nathanael, additional, Cant, David J. H., additional, Ramasamy, Karthik, additional, Albrasi, Enteisar, additional, Al-Chaghouri, Hanan, additional, Syres, Karen L., additional, O'Brien, Paul, additional, Flavell, Wendy R., additional, Mubofu, Egid, additional, Bondino, Federica, additional, and Magnano, Elena, additional

Published
2015
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24. Combining orthogonal measurements to unveil diclofenac encapsulation into polymeric and lipid nanocarriers.

Author

Marques SS, Cant DJH, Minelli C, and Segundo MA

Subjects
Polylactic Acid-Polyglycolic Acid Copolymer, Polyglycolic Acid chemistry, Lactic Acid chemistry, Lipids, Particle Size, Drug Carriers chemistry, Diclofenac, Nanoparticles chemistry
Abstract

The quantification of the drug associated to nanoparticle carriers, often expressed in terms of encapsulation efficiency, is a regulatory requirement. The establishment of independent methods to evaluate this parameter provides a means for measurement validation, which is critical in providing confidence in the methods and enabling the robust characterization of nanomedicines. Chromatography is traditionally used to measure drug encapsulation into nanoparticles. Here, we describe an additional independent strategy based on analytical centrifugation. The encapsulation of diclofenac into nanocarriers was quantified based on the mass difference between placebo (i.e. unloaded) and loaded nanoparticles. This difference was estimated using particle densities measured by differential centrifugal sedimentation (DCS) and size and concentration values measured by particle tracking analysis (PTA). The proposed strategy was applied to two types of formulations, namely poly(lactic-co-glycolic acid) (PLGA) nanoparticles and nanostructured lipid carriers, which were analysed by DCS operated in sedimentation and flotation modes, respectively. The results were compared to those from high performance liquid chromatography (HPLC) measurements. Additionally, X-ray photoelectron spectroscopy analysis was used to elucidate the surface chemical composition of the placebo and loaded nanoparticles. The proposed approach enables the monitoring of batch-to-batch consistency and the quantification of diclofenac association to PLGA nanoparticles from 0.7 ng to 5 ng of drug per 1 μg of PLGA, with good linear correlation between DCS and HPLC results (R 2  = 0.975). Using the same approach, similar quantification in lipid nanocarriers was possible for a loading of diclofenac ≥1.1 ng per 1 μg of lipids, with results in agreement with the HPLC method (R 2  = 0.971). Hence, the strategy proposed here expands the analytical tools available for evaluating nanoparticles encapsulation efficiency, being thus significant for increasing the robustness of drug-delivery nanocarriers characterization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Published
2023
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25. Measurement of Peptide Coating Thickness and Chemical Composition Using XPS.

Author

Cant DJH, Shard AG, and Minelli C

Subjects
Nanoparticles chemistry, Surface Properties, Peptides chemistry, Photoelectron Spectroscopy methods
Abstract

X-ray photoelectron spectroscopy is a highly surface-sensitive analytical technique, capable of providing quantitative information on the chemical composition of materials within the top ∼10 nm of their surface. For samples consisting of distinct underlayer and overlayer materials, the thickness of the coating can also be determined if it falls within this ∼10 nm information depth, which is often the case for peptide layers. Such measurements are simple to perform for flat samples and can also be performed on nanoparticulate samples provided that either the core radius or total particle radius are known. Here, we describe a straightforward protocol for obtaining such measurements from peptide coatings on both flat surfaces and nanoparticles, including preparation of nanoparticle samples from suspension, data acquisition, and analysis.

Published
2021
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26. Exposure of mass-selected bimetallic Pt-Ti nanoalloys to oxygen explored using scanning transmission electron microscopy and density functional theory.

Author

Gholhaki S, Hung SH, Cant DJH, Blackmore CE, Shard AG, Guo Q, McKenna KP, and Palmer RE

Abstract

The response of nanoparticles to exposure to ambient conditions and especially oxidation is fundamental to the application of nanotechnology. Bimetallic platinum-titanium nanoparticles of selected mass, 30 kDa and 90 kDa, were produced using a magnetron sputtering gas condensation cluster source and deposited onto amorphous carbon TEM grids. The nanoparticles were analysed with a C s -corrected Scanning Transmission Electron Microscope (STEM) in High Angle Annular Dark Field (HAADF) mode. It was observed that prior to full Ti oxidation, Pt atoms were dispersed within a Ti shell. However, after full oxidation by prolonged exposure to ambient conditions prior to STEM, the smaller size 30 kDa particles form a single Pt core and the larger size 90 kDa particles exhibit a multi-core structure. Electron beam annealing induced a single core morphology in the larger particles. First principles density functional theory (DFT) calculations were employed to calculate the lowest energy structure of the Pt-Ti nanoparticles with and without the presence of oxygen. It was demonstrated that, as the concentration of oxygen increases, the lowest energy structure changes from dispersed Pt to multiple Pt cores and finally a single Pt core, which is in good agreement with the experimental observations., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Published
2018
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