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Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), Kruit, P. (author)In electron optics, calculation of the electric field plays a major role in all computations and simulations. Accurate field calculation methods such as the finite element method (FEM), boundary element method and finite difference method, have been used for years. However, such methods are computationally very expensive and make the computer...journal article 2024
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Hari, S. (author), van Dorp, Willem F. (author), Mulders, Johannes J.L. (author), Trompenaars, Piet H.F. (author), Kruit, P. (author), Hagen, C.W. (author)Structures fabricated using focused electron beam-induced deposition (FEBID) have sloped sidewalls because of the very nature of the deposition process. For applications this is highly undesirable, especially when neighboring structures are interconnected. A new technique combining FEBID and focused electron beam-induced etching (FEBIE) has...journal article 2024
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Hagen, W.R. (author)The electron–electron, or zero-field interaction (ZFI) in the electron paramagnetic resonance (EPR) of high-spin transition ions in metalloproteins and coordination complexes, is commonly described by a simple spin Hamiltonian that is second-order in the spin S: ℋ=[2−(+1)/3+(2−2). Symmetry considerations, however, allow for fourth-order terms...journal article 2024
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Hagen, W.R. (author)Electron paramagnetic resonance spectroscopy is a long-standing method for the exploration of electronic structures of transition ion complexes. The difficulty of its analysis varies considerably, not only with the nature of the spin system, but more so with the relative magnitudes of the magnetic interactions to which the spin is subject, where...journal article 2023
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Hagen, W.R. (author)A broadband EPR spectrometer is an instrument that can be tuned to many microwave frequencies over several octaves. Its purpose is the collection of multi-frequency data, whose global analysis affords interpretation of complex spectra by means of deconvolution of frequency-dependent and frequency-independent interaction terms. Such spectra...journal article 2023
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Chan, H.W. (author), Prodanovic, V. (author), Theulings, A.M.M.G. (author), Tao, S. (author), Smedley, J. (author), Hagen, C.W. (author), Sarro, Pasqualina M (author), v.d. Graaf, H. (author)In this work we demonstrate that ultra-thin (5 and 15 nm) MgO transmission dynodes with sufficient high transmission electron yield (TEY) can be constructed. These transmission dynodes act as electron amplification stages in a novel vacuum electron multiplier: the Timed Photon Counter. The ultra-thin membranes with a diameter of 30 μm are...journal article 2023
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Hagen, W.R. (author), Louro, Ricardo O. (author)Distances between Fe ions in multiheme cytochromes are sufficiently short to make the intramolecular dipole-dipole interaction between hemes probable. In the analysis of EPR data from cytochromes, this interaction has thus far been ignored under the assumption that spectra are the simple sum of non-interacting components. Here, we use a...journal article 2023
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Theulings, A.M.M.G. (author), Tao, S. X. (author), Hagen, C.W. (author), van der Graaf, H. (author)The effect of doping in Si3N4 membranes on the secondary electron yield is investigated using Monte Carlo simulations of the electron-matter interactions. The effect of the concentration and the distribution of the doping in silicon rich silicon nitride membranes is studied by using the energy loss function as obtained from ab initio density...journal article 2022
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Hagen, W.R. (author)An EPR spectrometer has been developed that can be tuned to many frequencies in the range of ca 0.1–15 GHz. Applicability has been tested on ferrimyoglobin fluoride (MbF) and ferrimyoglobin cyanide (MbCN). MbF has a high-spin (S = 5/2) spectrum with <sup>19</sup>F superhyperfine splitting that is only resolved in X-band along the heme normal....journal article 2022
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Stolk, A.J. (author), van der Enden, K.L. (author), Röhsner, M. (author), Teepe, A. (author), Faes, S. O.F. (author), Bradley, C.E. (author), Cadot, S.P.A. (author), van Rantwijk, J.F. (author), te Raa, I. (author), Hagen, R.A.J. (author), Verlaan, A. L. (author), Biemond, J.J.B. (author), Khorev, A. (author), Vollmer, R. (author), Morits, J.P.J. (author), Taminiau, T.H. (author), van Zwet, E.J. (author), Hanson, R. (author)Entanglement distribution over quantum networks has the promise of realizing fundamentally new technologies. Entanglement between separated quantum processing nodes has been achieved on several experimental platforms in the past decade. To move toward metropolitan-scale quantum network test beds, the creation and transmission of...journal article 2022
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Hari, S. (author), Slotman, Johan A. (author), Vos, Y. (author), Floris, Christian (author), van Cappellen, W.A. (author), Hagen, C.W. (author), Stallinga, S. (author), Houtsmuller, A.B. (author), Hoogenboom, J.P. (author)Super-resolution fluorescence microscopy can be achieved by image reconstruction after spatially patterned illumination or sequential photo-switching and read-out. Reconstruction algorithms and microscope performance are typically tested using simulated image data, due to a lack of strategies to pattern complex fluorescent patterns with...journal article 2022
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Hagen, W.R. (author)Analysis of citation networks in biomedical research has indicated that belief in a specific scientific claim can gain unfounded authority through citation bias (systematic ignoring of papers that contain content conflicting with a claim), amplification (citation to papers that don't contain primary data), and invention (citing content but...journal article 2022
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Hagen, W.R. (author), Mills, Randell L. (author)Quantum mechanics postulates that the hydrogen atom has a stable ground state from which it can be promoted to excited states by capture of electromagnetic radiation, with the energy of all possible states given by E<sub>n</sub> = −13.598/n<sup>2</sup> eV, in which n ≥ 1 is a positive integer. It has been previously proposed that the n = 1...journal article 2022
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- Ji, Yuxuan (author), Wei, Li (author), Da, Anqi (author), Stark, Holger (author), Hagedoorn, P.L. (author), Ciofi-Baffoni, Simone (author), Cowley, Sally A. (author), James, William S. (author), Hagen, W.R. (author) journal article 2022
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Chan, H.W. (author), Prodanovic, V. (author), Theulings, A.M.M.G. (author), ten Bruggencate, T. (author), Hagen, C.W. (author), Sarro, Pasqualina M (author), van der Graaf, H. (author)Large-area transmission dynodes were fabricated by depositing an ultra-thin continuous film on a silicon wafer with a 3-dimensional pattern. After removing the silicon, a corrugated membrane with enhanced mechanical properties was formed. Mechanical metamaterials, such as this corrugated membrane, are engineered to improve its strength and...journal article 2022
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Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Mohammadi Gheidari, A. (author), Kruit, P. (author), Hagen, C.W. (author)The design of an electrostatic electron optical system with five electrodes and two objective functions is optimized using multiobjective genetic algorithms (MOGAs) optimization. The two objective functions considered are minimum probe size of the primary electron beam in a fixed image plane and maximum secondary electron detection efficiency...journal article 2021
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Hagen, W.R. (author)A previously developed spectrometer for broadband electron paramagnetic resonance (EPR) spectroscopy of dilute randomly oriented systems has been considerably modified to extend the frequency reach down to the hundred MHz range and to boost concentration sensitivity by 1 to 2 orders of magnitude. The instrument is now suitable for the study...journal article 2021
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Chan, H.W. (author), Prodanovic, V. (author), Theulings, A.M.M.G. (author), Hagen, C.W. (author), Sarro, Pasqualina M (author), v.d. Graaf, H. (author)The (secondary) electron emission from multilayered Al2O3/TiN membranes has been investigated with a hemispherical collector system in a scanning electron microscope for electrons with energies between 0.3 and 10 keV. These ultra-thin membranes are designed to function as transmission dynodes in novel vacuum electron multipliers. Two...journal article 2021
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Smith, C.S. (author), Slotman, Johan A. (author), Schermelleh, Lothar (author), Chakrova, N. (author), Hari, S. (author), Vos, Y. (author), Hagen, C.W. (author), Houtsmuller, A.B. (author), Hoogenboom, J.P. (author), Stallinga, S. (author)Super-resolution structured illumination microscopy (SIM) has become a widely used method for biological imaging. Standard reconstruction algorithms, however, are prone to generate noise-specific artifacts that limit their applicability for lower signal-to-noise data. Here we present a physically realistic noise model that explains the...journal article 2021
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Puschmann, J. (author), Mahor, D. (author), De Geus, Daniël C. (author), Strampraad, M.J.F. (author), Srour, B. (author), Hagen, W.R. (author), Todorovic, Smilja (author), Hagedoorn, P.L. (author)The heme enzyme chlorite dismutase (Cld) catalyzes O-O bond formation as part of the conversion of the toxic chlorite (ClO2-) to chloride (Cl-) and molecular oxygen (O2). Enzymatic O-O bond formation is rare in nature, and therefore, the reaction mechanism of Cld is of great interest. Microsecond timescale pre-steady-state kinetic experiments...journal article 2021