Towards a quantitative theory for transmission X-ray microscopy

Transmission X-ray microscopes (TXMs) are now increasingly used for quantitative analysis of samples, most notably in the spectral analysis of materials. Validating such measurements requires quantitatively accurate models for these microscopes, but current TXM models have only been tested qualitati...

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Main Authors: James G. McNally, Christoph Pratsch, Stephan Werner, Stefan Rehbein, Andrew Gibbs, Jihao Wang, Thomas Lunkenbein, Peter Guttmann, Gerd Schneider
Format: Article
Language:English
Published: Beilstein-Institut 2025-07-01
Series:Beilstein Journal of Nanotechnology
Subjects:
Online Access:https://doi.org/10.3762/bjnano.16.82
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author James G. McNally
Christoph Pratsch
Stephan Werner
Stefan Rehbein
Andrew Gibbs
Jihao Wang
Thomas Lunkenbein
Peter Guttmann
Gerd Schneider
author_facet James G. McNally
Christoph Pratsch
Stephan Werner
Stefan Rehbein
Andrew Gibbs
Jihao Wang
Thomas Lunkenbein
Peter Guttmann
Gerd Schneider
author_sort James G. McNally
collection DOAJ
description Transmission X-ray microscopes (TXMs) are now increasingly used for quantitative analysis of samples, most notably in the spectral analysis of materials. Validating such measurements requires quantitatively accurate models for these microscopes, but current TXM models have only been tested qualitatively. Here we develop an experimental and theoretical framework for evaluation of TXMs that uses Mie theory to compute the electric field emerging from a nanosphere. We approximate the microscope’s condenser illumination by plane waves at the mean illumination angle and the zone plate by a thin lens. We find that this model produces good qualitative agreement with our 3D measurements of 60 nm gold nanospheres, but only if both β and δ for the complex refractive index n = 1 – δ + iβ of gold are included in the model. This shows that both absorption and phase properties of the specimen influence the acquired TXM image. The qualitative agreement improves if we incorporate a small tilt into the condenser illumination relative to the optical axis, implying a small misalignment in the microscope. Finally, in quantitative comparisons, we show that the model predicts the nanosphere’s expected absorption as determined by Beer’s law, whereas the microscope underestimates this absorption by 10–20%. This surprising observation highlights the need for future work to identify the microscope feature(s) that lead to this quantitative discrepancy.
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spelling doaj-art-97b580ac5b254df699de37e5c99b012e2025-08-20T03:12:35ZengBeilstein-InstitutBeilstein Journal of Nanotechnology2190-42862025-07-011611113112810.3762/bjnano.16.822190-4286-16-82Towards a quantitative theory for transmission X-ray microscopyJames G. McNally0Christoph Pratsch1Stephan Werner2Stefan Rehbein3Andrew Gibbs4Jihao Wang5Thomas Lunkenbein6Peter Guttmann7Gerd Schneider8Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany Department of Mathematics, University College London, London, UK Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck Gesellschaft, Berlin, Germany Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck Gesellschaft, Berlin, Germany Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany Transmission X-ray microscopes (TXMs) are now increasingly used for quantitative analysis of samples, most notably in the spectral analysis of materials. Validating such measurements requires quantitatively accurate models for these microscopes, but current TXM models have only been tested qualitatively. Here we develop an experimental and theoretical framework for evaluation of TXMs that uses Mie theory to compute the electric field emerging from a nanosphere. We approximate the microscope’s condenser illumination by plane waves at the mean illumination angle and the zone plate by a thin lens. We find that this model produces good qualitative agreement with our 3D measurements of 60 nm gold nanospheres, but only if both β and δ for the complex refractive index n = 1 – δ + iβ of gold are included in the model. This shows that both absorption and phase properties of the specimen influence the acquired TXM image. The qualitative agreement improves if we incorporate a small tilt into the condenser illumination relative to the optical axis, implying a small misalignment in the microscope. Finally, in quantitative comparisons, we show that the model predicts the nanosphere’s expected absorption as determined by Beer’s law, whereas the microscope underestimates this absorption by 10–20%. This surprising observation highlights the need for future work to identify the microscope feature(s) that lead to this quantitative discrepancy.https://doi.org/10.3762/bjnano.16.823d imagingmathematical modelmie theorynanoparticletransmission x-ray microscope
spellingShingle James G. McNally
Christoph Pratsch
Stephan Werner
Stefan Rehbein
Andrew Gibbs
Jihao Wang
Thomas Lunkenbein
Peter Guttmann
Gerd Schneider
Towards a quantitative theory for transmission X-ray microscopy
Beilstein Journal of Nanotechnology
3d imaging
mathematical model
mie theory
nanoparticle
transmission x-ray microscope
title Towards a quantitative theory for transmission X-ray microscopy
title_full Towards a quantitative theory for transmission X-ray microscopy
title_fullStr Towards a quantitative theory for transmission X-ray microscopy
title_full_unstemmed Towards a quantitative theory for transmission X-ray microscopy
title_short Towards a quantitative theory for transmission X-ray microscopy
title_sort towards a quantitative theory for transmission x ray microscopy
topic 3d imaging
mathematical model
mie theory
nanoparticle
transmission x-ray microscope
url https://doi.org/10.3762/bjnano.16.82
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