Lohse, Leon Merten

[["dc.bibliographiccitation.firstpage","9842"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Optics Express"],["dc.bibliographiccitation.lastpage","9859"],["dc.bibliographiccitation.volume","28"],["dc.contributor.author","Lohse, L. M."],["dc.contributor.author","Vassholz, M."],["dc.contributor.author","Töpperwien, M."],["dc.contributor.author","Jentschke, T."],["dc.contributor.author","Bergamaschi, A."],["dc.contributor.author","Chiriotti, S."],["dc.contributor.author","Salditt, Tim"],["dc.date.accessioned","2020-12-10T18:42:02Z"],["dc.date.available","2020-12-10T18:42:02Z"],["dc.date.issued","2020"],["dc.description.abstract","A main challenge in x-ray µCT with laboratory radiation derives from the broad spectral content, which in contrast to monochromatic synchrotron radiation gives rise to reconstruction artifacts and impedes quantitative reconstruction. Due to the low spectral brightness of these sources, monochromatization is unfavorable and parallel recording of a broad bandpath is practically indispensable. While conventional CT sums up all spectral components into a single detector value, spectral CT discriminates the data in several spectral bins. Here we show that a new generation of charge integrating and interpolating pixel detectors is ideally suited to implement spectral CT with a resolution in the range of 10 µm. We find that the information contained in several photon energy bins largely facilitates automated classification of materials, as demonstrated for of a mouse cochlea. Bones, soft tissues, background and metal implant materials are discriminated automatically. Importantly, this includes taking a better account of phase contrast effects, based on tailoring reconstruction parameters to specific energy bins."],["dc.identifier.doi","10.1364/OE.385389"],["dc.identifier.eissn","1094-4087"],["dc.identifier.pmid","32225584"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/17771"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/77783"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.relation.issn","1094-4087"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.subject.gro","x-ray imaging"],["dc.subject.gro","biomedical tomography"],["dc.title","Spectral µCT with an energy resolving and interpolating pixel detector"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","480"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Acta Crystallographica. Section A, Foundations and Advances"],["dc.bibliographiccitation.lastpage","496"],["dc.bibliographiccitation.volume","77"],["dc.contributor.affiliation","Vassholz, Malte; 1Universität GöttingenInstitut für RöntgenphysikGermany"],["dc.contributor.affiliation","Salditt, Tim; 1Universität GöttingenInstitut für RöntgenphysikGermany"],["dc.contributor.author","Lohse, Leon Merten"],["dc.contributor.author","Vaßholz, Malte"],["dc.contributor.author","Salditt, Tim"],["dc.creator.author","Leon M. Lohse"],["dc.creator.author","Malte Vassholz"],["dc.creator.author","Tim Salditt"],["dc.date.accessioned","2021-09-21T15:39:39Z"],["dc.date.available","2021-09-21T15:39:39Z"],["dc.date.issued","2021-09"],["dc.date.updated","2022-03-20T23:56:24Z"],["dc.description.abstract","Incoherent diffractive imaging (IDI) promises structural analysis with atomic resolution based on intensity interferometry of pulsed X‐ray fluorescence emission. However, its experimental realization is still pending and a comprehensive theory of contrast formation has not been established to date. Explicit expressions are derived for the equal‐pulse two‐point intensity correlations, as the principal measured quantity of IDI, with full control of the prefactors, based on a simple model of stochastic fluorescence emission. The model considers the photon detection statistics, the finite temporal coherence of the individual emissions, as well as the geometry of the scattering volume. The implications are interpreted in view of the most relevant quantities, including the fluorescence lifetime, the excitation pulse, as well as the extent of the scattering volume and pixel size. Importantly, the spatiotemporal overlap between any two emissions in the sample can be identified as a crucial factor limiting the contrast and its dependency on the sample size can be derived. The paper gives rigorous estimates for the optimum sample size, the maximum photon yield and the expected signal‐to‐noise ratio under optimal conditions. Based on these estimates, the feasibility of IDI experiments for plausible experimental parameters is discussed. It is shown in particular that the mean number of photons per detector pixel which can be achieved with X‐ray fluorescence is severely limited and as a consequence imposes restrictive constraints on possible applications."],["dc.description.abstract","Starting from a simple model of stochastic fluorescence emission, a theory is derived of contrast formation and signal‐to‐noise ratio for incoherent diffractive imaging; its feasibility for plausible experimental parameters is discussed. image"],["dc.identifier.doi","10.1107/S2053273321007300"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/89704"],["dc.language.iso","en"],["dc.relation","SFB 1456 | Cluster C | C03: Intensity correlations in diffraction experiments: convolution, reconstruction and information"],["dc.relation","SFB 1456 | Cluster C: Data with Information in Their Dependency Structure"],["dc.relation","SFB 1456: Mathematik des Experiments: Die Herausforderung indirekter Messungen in den Naturwissenschaften"],["dc.relation","SFB 1456 | Cluster A | A03: Dimensionality reduction and regression in Wasserstein space for quantitative 3D histology"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.rights","This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited."],["dc.subject.gro","x-ray imaging"],["dc.title","On incoherent diffractive imaging"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","852"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Journal of Synchrotron Radiation"],["dc.bibliographiccitation.lastpage","859"],["dc.bibliographiccitation.volume","27"],["dc.contributor.author","Lohse, Leon Merten"],["dc.contributor.author","Robisch, Anna Lena"],["dc.contributor.author","Töpperwien, Mareike"],["dc.contributor.author","Maretzke, Simon"],["dc.contributor.author","Krenkel, Martin"],["dc.contributor.author","Hagemann, Johannes"],["dc.contributor.author","Salditt, Tim"],["dc.date.accessioned","2020-12-10T18:25:59Z"],["dc.date.available","2020-12-10T18:25:59Z"],["dc.date.issued","2020"],["dc.description.abstract","Propagation-based phase-contrast X-ray imaging is by now a well established imaging technique, which – as a full-field technique – is particularly useful for tomography applications. Since it can be implemented with synchrotron radiation and at laboratory micro-focus sources, it covers a wide range of applications. A limiting factor in its development has been the phase-retrieval step, which was often performed using methods with a limited regime of applicability, typically based on linearization. In this work, a much larger set of algorithms, which covers a wide range of cases (experimental parameters, objects and constraints), is compiled into a single toolbox – the HoloTomoToolbox – which is made publicly available. Importantly, the unified structure of the implemented phase-retrieval functions facilitates their use and performance test on different experimental data."],["dc.identifier.doi","10.1107/S1600577520002398"],["dc.identifier.eissn","1600-5775"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/75904"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.relation.issn","1600-5775"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.rights","CC BY 4.0"],["dc.subject.gro","x-ray imaging"],["dc.subject.gro","biomedical tomography"],["dc.title","A phase-retrieval toolbox for X-ray holography and tomography"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2494"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","ChemCatChem"],["dc.bibliographiccitation.lastpage","2507"],["dc.bibliographiccitation.volume","13"],["dc.contributor.author","Veselý, Martin"],["dc.contributor.author","Valadian, Roozbeh"],["dc.contributor.author","Lohse, Leon Merten"],["dc.contributor.author","Töpperwien, Mareike"],["dc.contributor.author","Spiers, Kathryn"],["dc.contributor.author","Garrevoet, Jan"],["dc.contributor.author","Vogt, Eelco T. C."],["dc.contributor.author","Salditt, Tim"],["dc.contributor.author","Weckhuysen, Bert M."],["dc.contributor.author","Meirer, Florian"],["dc.date.accessioned","2021-08-22T15:31:06Z"],["dc.date.available","2021-08-22T15:31:06Z"],["dc.date.issued","2021-03-31"],["dc.description.abstract","Catalyst deactivation involves a complex interplay of processes taking place at different length and time scales. Understanding this phenomenon is one of the grand challenges in solid catalyst characterization. A process contributing to deactivation is carbon deposition (i. e., coking), which reduces catalyst activity by limiting diffusion and blocking active sites. However, characterizing coke formation and its effects remains challenging as it involves both the organic and inorganic phase of the catalytic process and length scales from the atomic scale to the scale of the catalyst body. Here we present a combination of hard X-ray imaging techniques able to visualize in 3-D the distribution, effect and nature of carbon deposits in the macro-pore space of an entire industrially used catalyst particle. Our findings provide direct evidence for coke promoting effects of metal poisons, pore clogging by coke, and a correlation between carbon nature and its location. These results provide a better understanding of the coking process, its relation to catalyst deactivation and new insights into the efficiency of the industrial scale process of fluid catalytic cracking."],["dc.identifier.doi","10.1002/cctc.202100276"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/88786"],["dc.language.iso","en"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.rights","CC BY 4.0"],["dc.subject.gro","x-ray imaging"],["dc.title","3‐D X‐ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","063804"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Physical Review. A"],["dc.bibliographiccitation.volume","96"],["dc.contributor.author","Vassholz, Malte"],["dc.contributor.author","Lohse, Leon Merten"],["dc.contributor.author","Salditt, Tim"],["dc.contributor.orcid","0000-0002-0368-8782"],["dc.creator.author","Vassholz, Malte"],["dc.date.accessioned","2022-11-21T10:16:44Z"],["dc.date.available","2022-11-21T10:16:44Z"],["dc.date.issued","2017"],["dc.description.abstract","Recently, an approach to tomography with extended anisotropic radiation sources has been introduced, which helps to overcome the challenges resulting from the low brilliance typical for x-ray laboratory sources. The method is based on the three-dimensional Radon transform (3DRT) which uses planar integrals instead of line integrals. By extending the source spot in one direction, more photons can contribute to image formation while the impact on the resolution is minor with the 3DRT approach. In this work we present a more comprehensive description of the method, derive quantitative error estimates for the extraction of these planar integrals measured with a finite source size, and validate the 3DRT scheme by analytical theory. We also demonstrate a simple and efficient reconstruction algorithm for 3D Radon data. Finally, we further substantiate the method with experimental results obtained at a microfocus x-ray source with an extremely anisotropic source spot."],["dc.identifier.doi","10.1103/physreva.96.063804"],["dc.identifier.gro","3142463"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/117175"],["dc.identifier.url","https://publications.goettingen-research-online.de/handle/2/13613"],["dc.language.iso","en"],["dc.notes.intern","lifescience updates Crossref Import"],["dc.notes.status","final"],["dc.relation.eissn","2469-9934"],["dc.relation.issn","2469-9926"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.rights","CC BY 4.0"],["dc.subject.gro","x-ray imaging"],["dc.subject.gro","biomedical tomography"],["dc.title","Tomography with extended sources: Theory, error estimates, and a reconstruction algorithm"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]