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Franz Pfeiffer

Contact Details

franz_pfeiffer

Prof. Dr. Franz Pfeiffer

Physics Department (E17) & Institute of Medical Engineering (IMETUM)
Technische Universität München
James-Franck-Straße
85748 Garching / Germany

Email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Phone: +49 89 289 12552
Fax: +49 89 289 12548

 

Scientific expertise

  • X-ray Physics and Applications
  • Biomedical Imaging/ Computed Tomography
  • X-Ray and Neutron Optics
  • Synchrotron Instrumentation
  • Microscopy

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Thibault, P., Dierolf, M., Menzel, A., Bunk, O., David, C. & Pfeiffer, F. (2008), "High-resolution scanning x-ray diffraction microscopy", Science. Vol. 321(5887), pp. 379-382.

[Abstract] [BibTeX] [DOI]
Abstract: Coherent diffractive imaging (CDI) and scanning transmission x-ray microscopy (STXM) are two popular microscopy techniques that have evolved quite independently. CDI promises to reach resolutions below 10 nanometers, but the reconstruction procedures put stringent requirements on data quality and sample preparation. In contrast, STXM features straightforward data analysis, but its resolution is limited by the spot size on the specimen. We demonstrate a ptychographic imaging method that bridges the gap between CDI and STXM by measuring complete diffraction patterns at each point of a STXM scan. The high penetration power of x-rays in combination with the high spatial resolution will allow investigation of a wide range of complex mesoscopic life and material science specimens, such as embedded semiconductor devices or cellular networks.
BibTeX: 
@article{Thibault2008,
  author = {Thibault, P. and Dierolf, M. and Menzel, A. and Bunk, O. and David, C. and Pfeiffer, F.},
  title = {High-resolution scanning x-ray diffraction microscopy},
  journal = {Science},
  year = {2008},
  volume = {321},
  number = {5887},
  pages = {379--382},
  doi = {http://dx.doi.org/10.1126/science.1158573}
}
Weitkamp, T., David, C., Bunk, O., Bruder, J., Cloetens, P. & Pfeiffer, F. (2008), "X-ray phase radiography and tomography of soft tissue using grating interferometry", European Journal of Radiology. Vol. 68(3), pp. S13-S17.

[Abstract] [BibTeX] [DOI]
Abstract: X-ray phase and absorption radiographs and tomograms of the heart of a rat were taken with an X-ray grating interferometer with monochromatic synchrotron radiation at a photon energy of 17.5 keV. The phase images show largely superior quality with respect to the absorption images taken with the same dose, particularly much better contrast and contrast-to-noise ratio. Different tissues can clearly be distinguished. The results demonstrate the potential of grating interferometry for two- and three-dimensional X-ray imaging of biological soft tissue in an aqueous environment. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
BibTeX: 
@article{Weitkamp2008,
  author = {Weitkamp, T. and David, C. and Bunk, O. and Bruder, J. and Cloetens, P. and Pfeiffer, F.},
  title = {X-ray phase radiography and tomography of soft tissue using grating interferometry},
  journal = {European Journal of Radiology},
  year = {2008},
  volume = {68},
  number = {3},
  pages = {S13--S17},
  doi = {http://dx.doi.org/10.1016/j.ejrad.2008.04.031}
}
Bunk, O., Diaz, A., Pfeiffer, F., David, C., Padeste, C., Keymeulen, H., Willmott, P.R., Patterson, B.D., Schmitt, B., Satapathy, D.K., van der Veen, J.F., Guo, H. & Wegdam, G.H. (2007), "Confinement-induced liquid ordering investigated by x-ray phase retrieval", Physical Review E. Vol. 75(2), pp. 021501.

[Abstract] [BibTeX] [DOI]
Abstract: Using synchrotron x-ray diffraction, we have determined the ensemble-averaged density profile of colloidal fluids within confining channels of different widths. We observe an oscillatory ordering-disordering behavior of the colloidal particles as a function of the channel width, while the colloidal solution remains in the liquid state. This phenomenon has been suggested by surface force studies of hard-sphere fluids and also theoretically predicted, but here we see it by direct measurements of the structure for comparable systems.
BibTeX: 
@article{Bunk2007,
  author = {Bunk, O. and Diaz, A. and Pfeiffer, F. and David, C. and Padeste, C. and Keymeulen, H. and Willmott, P. R. and Patterson, B. D. and Schmitt, B. and Satapathy, D. K. and van der Veen, J. F. and Guo, H. and Wegdam, G. H.},
  title = {Confinement-induced liquid ordering investigated by x-ray phase retrieval},
  journal = {Physical Review E},
  year = {2007},
  volume = {75},
  number = {2},
  pages = {021501},
  doi = {http://dx.doi.org/10.1103/PhysRevE.75.021501}
}
Bunk, O., Diaz, A., Pfeiffer, F., David, C., Schmitt, B., Satapathy, D.K. & van der Veen, J.F. (2007), "Diffractive imaging for periodic samples: retrieving one-dimensional concentration profiles across microfluidic channels", Acta Crystallographica Section A. Vol. 63, pp. 306-314.

[Abstract] [BibTeX] [DOI]
Abstract: A technique has been developed that allows determination of the concentration profiles of colloidal solutions or any kind of fluid under confinement. Currently, submicrometre-wide channels are sampled with a resolution in the 10 nm range. The method comprises regular arrays of microfluidic channels and one-dimensional X-ray phase-retrieval techniques for the analysis of small-angle X-ray diffraction from the array structures. Recording the X-ray diffraction data requires a low dose on each individual channel since the sum of the signals from all channels is detected. The determined concentration profiles represent the ensemble average rather than individual entities and are obtained in a model-independent way. As an example, amplitude and phase of the exit field and concentration profiles for a colloidal fluid within confining channels of different widths are shown.
BibTeX: 
@article{Bunk2007a,
  author = {Bunk, O. and Diaz, A. and Pfeiffer, F. and David, C. and Schmitt, B. and Satapathy, D. K. and van der Veen, J. F.},
  title = {Diffractive imaging for periodic samples: retrieving one-dimensional concentration profiles across microfluidic channels},
  journal = {Acta Crystallographica Section A},
  year = {2007},
  volume = {63},
  pages = {306--314},
  doi = {http://dx.doi.org/10.1107/S0108767307021903}
}
David, C., Bruder, J., Rohbeck, T., Grunzweig, C., Kottler, C., Diaz, A., Bunk, O. & Pfeiffer, F. (2007), "Fabrication of diffraction gratings for hard X-ray phase contrast imaging", Microelectronic Engineering. Vol. 84(5-8), pp. 1172-1177.

[Abstract] [BibTeX] [DOI]
Abstract: We have developed a method for X-ray phase contrast imaging, which is based on a grating interferometer. The technique is capable of recording the phase shift of hard X-rays travelling through a sample, which greatly enhances the contrast of low absorbing specimen compared to conventional amplitude contrast images. Unlike other existing X-ray phase contrast imaging methods, the grating interferometer also works with incoherent radiation from a standard X-ray tube. The key components are three gratings with silicon and gold structures, which have dimensions in the micrometer range and high aspect ratios. The fabrication processes, which involve photolithography, anisotropic wet etching, and electroplating, are described in this article for each of the three gratings. An example of an X-ray phase contrast image acquired with the grating interferometer is given. (c) 2007 Elsevier B.V. All rights reserved.
BibTeX: 
@article{David2007,
  author = {David, C. and Bruder, J. and Rohbeck, T. and Grunzweig, C. and Kottler, C. and Diaz, A. and Bunk, O. and Pfeiffer, F.},
  title = {Fabrication of diffraction gratings for hard X-ray phase contrast imaging},
  journal = {Microelectronic Engineering},
  year = {2007},
  volume = {84},
  number = {5-8},
  pages = {1172--1177},
  doi = {http://dx.doi.org/10.1016/j.mee.2007.01.151}
}
David, C., Weitkamp, T., Pfeiffer, F., Diaz, A., Bruder, J., Rohbeck, T., Groso, A., Bunk, O., Stampanoni, M. & Cloetens, P. (2007), "Hard X-ray phase imaging and tomography using a grating interferometer", Spectrochimica Acta Part B-atomic Spectroscopy. Vol. 62(6-7), pp. 626-630.

[Abstract] [BibTeX] [DOI]
Abstract: An interferometric technique for hard X-rays is presented. It is based on two transmission gratings and a phase-stepping technique, and it provides separate radiographs of the phase and absorption profiles of bulk samples. Tomographic reconstruction yields quantitative threedimensional maps of the X-ray refractive index and of the attenuation coefficient, with a spatial resolution down to a few microns. The method is mechanically robust, it requires little monochromaticity, and can be scaled up to large fields of view. These are important prerequisites for use with laboratory X-ray sources. Numerous applications ranging from wave front sensing to medical radiography are presently under investigation. (c) 2007 Elsevier B.V All rights reserved.
BibTeX: 
@article{David2007a,
  author = {David, C. and Weitkamp, T. and Pfeiffer, F. and Diaz, A. and Bruder, J. and Rohbeck, T. and Groso, A. and Bunk, O. and Stampanoni, M. and Cloetens, P.},
  title = {Hard X-ray phase imaging and tomography using a grating interferometer},
  journal = {Spectrochimica Acta Part B-atomic Spectroscopy},
  year = {2007},
  volume = {62},
  number = {6-7},
  pages = {626--630},
  doi = {http://dx.doi.org/10.1016/j.sab.2007.03.001}
}
Engelhardt, M., Baumann, J., Schuster, M., Kottler, C., Pfeiffer, F., Bunk, O. & David, C. (2007), "Inspection of refractive x-ray lenses using high-resolution differential phase contrast imaging with a microfocus x-ray source", Review of Scientific Instruments. Vol. 78(9), pp. 093707.

[Abstract] [BibTeX] [DOI]
Abstract: A refractive x-ray lens was characterized using a magnifying cone beam setup for differential phase contrast imaging in combination with a microfocus x-ray tube. Thereby, the differential and the total phase shift of x rays transmitted through the lens were determined. Lens aberrations have been characterized based on these refractive properties. (c) 2007 American Institute of Physics.
BibTeX: 
@article{Engelhardt2007,
  author = {Engelhardt, M. and Baumann, J. and Schuster, M. and Kottler, C. and Pfeiffer, F. and Bunk, O. and David, C.},
  title = {Inspection of refractive x-ray lenses using high-resolution differential phase contrast imaging with a microfocus x-ray source},
  journal = {Review of Scientific Instruments},
  year = {2007},
  volume = {78},
  number = {9},
  pages = {093707},
  doi = {http://dx.doi.org/10.1063/1.2786273}
}
Engelhardt, M., Baumann, J., Schuster, M., Kottler, C., Pfeiffer, F., Bunk, O. & David, C. (2007), "High-resolution differential phase contrast imaging using a magnifying projection geometry with a microfocus x-ray source", Applied Physics Letters. Vol. 90(22), pp. 224101.

[Abstract] [BibTeX] [DOI]
Abstract: Differential x-ray phase contrast imaging using a grating interferometer was combined with a magnifying cone beam geometry using a conventional microfocus x-ray tube. This brings the advantages of a magnifying cone beam setup, namely, a high spatial resolution in the micron range and the possibility of using an efficient, low resolution detector, into differential phase contrast imaging. The authors present methodical investigations which show how the primary measurement signal depends on the magnification factor. As an illustration of the potential of this quantitative imaging technique, a high-resolution x-ray phase contrast tomography of an insect is presented. (C) 2007 American Institute of Physics.
BibTeX: 
@article{Engelhardt2007a,
  author = {Engelhardt, M. and Baumann, J. and Schuster, M. and Kottler, C. and Pfeiffer, F. and Bunk, O. and David, C.},
  title = {High-resolution differential phase contrast imaging using a magnifying projection geometry with a microfocus x-ray source},
  journal = {Applied Physics Letters},
  year = {2007},
  volume = {90},
  number = {22},
  pages = {224101},
  doi = {http://dx.doi.org/10.1063/1.2743928}
}
Jefimovs, K., Bunk, O., Pfeiffer, F., Grolimund, D., van der Veen, J.F. & David, C. (2007), "Fabrication of Fresnel zone plates for hard X-rays", Microelectronic Engineering. Vol. 84(5-8), pp. 1467-1470.

[Abstract] [BibTeX] [DOI]
Abstract: A method to fabricate gold structures with high aspect ratio is presented. Fresnel zone plates with an outermost zone width of 100 nm and structures of 1 mu m height are fabricated. Preliminary focusing results at an X-ray energy of 8 keV are presented and ways to improve the zone plate parameters are discussed. (c) 2007 Elsevier B.V. All rights reserved.
BibTeX: 
@article{Jefimovs2007,
  author = {Jefimovs, K. and Bunk, O. and Pfeiffer, F. and Grolimund, D. and van der Veen, J. F. and David, C.},
  title = {Fabrication of Fresnel zone plates for hard X-rays},
  journal = {Microelectronic Engineering},
  year = {2007},
  volume = {84},
  number = {5-8},
  pages = {1467--1470},
  doi = {http://dx.doi.org/10.1016/j.mee.2007.01.112}
}
Keymeulen, H.R., Diaz, A., Solak, H.H., David, C., Pfeiffer, F., Patterson, B.D., van der Veen, J.F., Stoykovich, M.P. & Nealey, P.F. (2007), "Measurement of the x-ray dose-dependent glass transition temperature of structured polymer films by x-ray diffraction", Journal of Applied Physics. Vol. 102(1), pp. 013528.

[Abstract] [BibTeX] [DOI]
Abstract: The glass transition temperature (T-g) of polymer nanostructures was measured using a technique based on synchrotron x-ray diffraction from periodic grating structures. Poly(methyl methacrylate) (PMMA) nanostructures consisting of 1:1 lines:spaces with a 100 nm period and 100 nm height were characterized to have a T-g of 118 degrees C, which is comparable to the T-g of PMMA in bulk systems. The T-g of the PMMA structures also was measured as a function of absorbed x-ray dose. Doses ranging from 0 to 2400 mJ/mm(3) were delivered to the PMMA structures prior to the T-g measurements; the T-g of the structures was found to decrease from 118 degrees C to 95 degrees C, respectively. The dose dependence of the PMMA glass transition temperature can be attributed to changes in the polymer molecular weight under exposure to x rays. (c) 2007 American Institute of Physics.
BibTeX: 
@article{Keymeulen2007,
  author = {Keymeulen, H. R. and Diaz, A. and Solak, H. H. and David, C. and Pfeiffer, F. and Patterson, B. D. and van der Veen, J. F. and Stoykovich, M. P. and Nealey, P. F.},
  title = {Measurement of the x-ray dose-dependent glass transition temperature of structured polymer films by x-ray diffraction},
  journal = {Journal of Applied Physics},
  year = {2007},
  volume = {102},
  number = {1},
  pages = {013528},
  doi = {http://dx.doi.org/10.1063/1.2752548}
}
Kottler, C., David, C., Pfeiffer, F. & Bunk, O. (2007), "A two-directional approach for grating based differential phase contrast imaging using hard x-rays", Optics Express. Vol. 15(3), pp. 1175-1181.

[Abstract] [BibTeX]
Abstract: We report on a two-directional approach for grating based x-ray differential phase contrast imaging. In order to retrieve good quality and artifact-free phase images for quantitative analysis and image processing, particular emphasis is put on the algorithm for proper phase retrieval. Examples of application are discussed that demonstrate the functionality of the method even in cases where the one-dimensional phase integration fails completely. (c) 2007 Optical Society of America.
BibTeX: 
@article{Kottler2007,
  author = {Kottler, C. and David, C. and Pfeiffer, F. and Bunk, O.},
  title = {A two-directional approach for grating based differential phase contrast imaging using hard x-rays},
  journal = {Optics Express},
  year = {2007},
  volume = {15},
  number = {3},
  pages = {1175--1181}
}