Dr. Benedikt Rösner

Benedikt Rösner
Profilbild Benedikt Rösner in Anzug mit Krawatte

Scientist for X-ray Optics:

High resolution lenses, free electron laser science, optical elements for specific beams

Paul Scherrer Institute
Forschungsstrasse 111
5232 Villigen PSI
Switzerland

X-ray transient gratings


Scheme of an X-ray Transient grating experiment. a) Experimental geometry at the Alvra endstation of SwissFEL. b) Fresnel simulation of the Talbot carpet: intensity modulation for a 1D diamond phase grating with a 200 nm pitch and 2.985 keV photon energy, resulting in a grating period of 190 nm at the sample (c).
The extension of transient grating spectroscopy to the X-ray regime is very appealing, opening possibilities ranging from the study of thermal transport in the ballistic regime to charge, spin, and energy transfer processes with atomic spatial and femtosecond temporal resolution. Studies involving complicated split-and-delay lines have not yet been successful in achieving this goal. In an experiment at SwissFEL, X-ray transient gratings were prepared using a simple method based on the Talbot effect for converging beams. By analyzing printed interference patterns on polymethyl methacrylate and gold samples using ∼3 keV X-ray pulses, a the experimental feasibility transient gratings in the hard X-ray regime was demonstrated.
Towards X-ray transient grating spectroscopy - Optics Letters

Tackling the timing problem in ultrafast spectroscopy: Simultaneous single shot, time-resolved demagnetization dynamics at two energies


Schematic illustration of the time-streaking principle. In this way, a time window of 3.3 ps can be covered at the iron M-edge (52.7 eV).
Streaking the time information in one dimension on a detector
X-ray free electron lasers exhibit unique capabilities to conduct resonant x-ray spectroscopy techniques on ultrafast time scales. Utilizing diffractive optical elements, the pathway difference inherent to diffraction can be exploited to streak the arrival time of an x-ray probe along a geometric dimension. This concept has been applied in a pioneering experiment in reflection geometry at FLASH with a time resolution of 120 fs: Single-shot Monitoring of Ultrafast Processes via X-ray Streaking at a Free Electron Laser.
Adapting the experiment to a transmission geometry, we investigated demagnetization dynamics of a CoDy film together with collaborators from CNRS, the University Pierre and Marie Curie, and at the FERMI free electron laser, see figure above. The time window reachable with this setup is 1.5 ps, theoratically limited by the wavelenght divided through the speed of light. In practice, the duration of the pump puls of approx. 100 fs is the limiting factor.
Extending the concept to multiple energies
Detector image of a time-streaking experiment using two energies. In this particular example, the sample is removed, and a shadow mask is placed in front of the off-axis zone plate to keep track of the experimental geometry.
Extending this scheme to take advantage of the other spatial dimension, more advanced experiments become possible. In particular, we aim at performing ultrafast spectroscopy. Advancing towards this goal, we have designed a specific optical element, which allows to perform time-streaking experiments at two distinct energies simultaneously. This allows us to investigate multicomponent systems at two different absorption edges, and to compare dynamics of two elements with exactly the same timing (without a different time zero).
Employing this scheme, we investigated the demagnetization dynamics in iron-nickel multilayer systems and alloys. The evaluation of the data is ongoing. In principle, the number of different energies is not limited and can be extended even to a continuous energy range.



Extreme ultraviolet vortices at free electron lasers


Top row: Spiral zone plates with topological charge l=0 (Fresnel zone plate), l=1, l=2 and l=3. Bottom row: Resulting phase at the wavefront.
Creation of EUV vortices
Extreme ultraviolet vortices can be described as radiation which carries an orbital angular momentum. In electromagnetic radiation from free electron laser and synchrotron sources, the electric and magnetic field can rotate uniformly clockwise or counterclockwise with respect to the light propagation, resulting in circular polarization. In vortices, it is the phase of the electromagnetic field that rotates around a circularity in a helical fashion. The vortex can be characterized with an integer-numbered topologic charge, which describes how often the wavefront is shifted around 360°.
To demonstrate optical vortices at free electron lasers, we fabricated spiral zone plates, which yield a diffraction pattern with such a phase singularity. The material of choice for the extremely intense EUV radiation of the FERMI free electron laser is silicon. We thus etched spiral zone plates into ultraflat thin silicon membranes, and characterized the radiation using a Hartmann wavefront sensor in the far field.
Viewpoint in APS Physics :: Wavefront Characterization of Optical Vortices - Phys. Rev. X

Left column: AFM images of the same polymer imprint as ablated (top), after development in a 1:3 mixture (middle), and in a 1:1 mixture of methylisobutylketone and isopropanole (bottom). Middle column: 3D cross sections of the craters. Right column: Reconstructed beam intensity on a logarithmic scale.
Beam profiling with an extended polymer imprint method
Beam profiling of free electron laser radiation in the focus of a Fresnel zone plate is a true challenge. An established method to characterize extremely intense beams in the EUV and soft X-ray regime is to shoot imprint craters into a material with well known damage attenuation length and threshold, and to characterize the form of the imprint crater. However, this method is limited to a dynamical range of approx. 100, with the consequence that the X-ray fluence has to be varied to get the full beam profile from maximum intensity to faint beam tails. We now adapted a method known from grayscale lithography of PMMA and treated imprint craters with organic solvents (or developers). In this way, additional material, which is exposed to radiation but not ablated, can be removed. We are able to show that the adapted method is extremely sensitive and enhances the dynamic range for beam profiling by an order of magnitude to 1000.
Beam Profiling by Development of Polymer Imprints - Opt. Express

Soft X-ray microscopy at the 7 nm level


A Fresnel zone plate for high resolution imaging- D = 240 µm, dr = 8.8 nm
Fresnel zone plates are diffractive lenses widely used in X-ray microscopy. As an intrinsic limit from diffraction, their resolution is approximately in the order of their outermost zone width. This induces a major challenge in nanofabrication to produce smaller and smaller nanostructures striving for better resolution. In recent years, zone dimensions and resolution in X-ray micrscopy have been approaching the 10 nanometre level.
We now aimed for demonstrating resolution beyond 10 nm. While zone plates have been reported on with focal spots well below 10 nm (cp. Mohacsi et al., Sci. Rep. 2017, Döring et al., Opt. Express 2013) reconstructed from the farfield, directly recorded X-ray micrographs have not been obtained so far. We thus fabricated zone plates with iridium zones with 9 nm (see above), and tested their resolution at the Hermes beamline at Soleil and the Pollux beamline at the Swiss Light Source. Indeed, these zone plates prove to be capable of resolving test structures with typical sizes below 10 nm. The following image shows a well-resolved periodic iridium structure with 9 nm line width.
A test structure consisting of periodic iridium lines with 9 nm line width. a) Scanning electron micrograph of a 200 x 200 nm wide field. b) X-ray transmission micrograph of a similar area with 1 nm step size. c) Fourier shell correlation, showing a frequency cut-off value of 7.1 nm.
The results are presented at the X-Ray Microscopy Conference in Saskatoon in August 2018. A publication is in preparation.

A detailed CV can be found here.

2019

B. Rösner, S. Finizio, F. Koch, F. Döring, V. A. Guzenko, A. Kleibert, M. Langer, E. Kirk, M. Meyer, J. L. Ornelas, A. Späth, R. H. Fink, S. Stanescu, S. Swaraj, R. Belkhou, B. Watts, J. Raabe, C. David
7 nm spatial resolution in soft X-ray microscopy and high resolution magnetic imaging
in preparation

G. Brenner, S. Dziarzhytski, P. S. Miedema, B. Rösner, C. David, M. Beye
Normalized single-shot X-ray absorption spectroscopy at a free-electron laser
Optics Letters 44, 2019, 2157-2160
https://doi.org/10.1364/OL.44.002157

E. Jal, M. Makita, B. Rösner, C. David, F. Nolting, J. Raabe, T. Savchenko, A. Kleibert, F. Capotondi, E. Pedersoli, L. Raimondi, M. Manfredda, I. Nikolov, X. Lui, A. Merhe, N. Jaouen, J. Gorchon, G. Malinowski, M. Hehn, B. Vodungbo, J. Lüning
Single-shot time-resolved magnetic x-ray absorption at a free-electron laser
Physical Review B 99, 2019, 144305
https://doi.org/10.1103/PhysRevB.99.144305


F. Döring, M. Risch, B. Rösner, M. Beye, P. Busse, K. Kubiček, L. Glaser, P. S. Miedema, J. Soltau, D. Raiser, V. A. Guzenko, L. Szabadics, L. Kochanneck, M. Baumung, J. Buck, C. Jooss, S. Techert, C. David
A zone plate based two-color spectrometer for indirect X-ray absorption spectroscopy
Journal of Synchrotron Radiation, accepted

B. Rösner, P. Dudin, J. Bosgra, M. Hoesch, C. David
Zone plates for angle-resolved photoelectron spectroscopy providing sub-micrometre resolution in the extreme ultraviolet regime
Journal of Synchrotron Radiation 26, 2019, 467-472
https://doi.org/10.1107/S1600577519000869

C. Sventina, R. Mankowsky, G. Knopp, F. Koch, G. Seniutinas, B. Rösner, A. Kubec, M. Lebugle, I. Mochi, M. Beck, C. Cirelli, J. Krempasky, C. Pradervand, J. Rouxel, G. F. Mancini, S. Zerdane, B. Pedrini, V. Esposito, G. Ingold, U. Wagner, U. Flechsig, R. Follath, M. Chergui, C. Milne, H. T. Lemke, C. David, P. Beaud
Towards X-ray Transient Grating Spectroscopy
Optics Letters 44, 2019, 574-577
https://doi.org/10.1364/OL.44.000574

S. Gottlieb, B. Rösner, L. Evangelio, M. Fernández-Regúlez, A. Nogales, M. C. García-Guitérrez, T. F. Keller, J. Fraxedas, T. A. Ezquerra, C. David, F. Perez-Murano
Self-assembly morphology of block copolymers in sub-10nm topological guiding patterns
Molecular Systems Design & Engineering 2019, Advance Article
https://doi.org/10.1039/C8ME00046H

2018

C. David, B. Rösner, F. Döring, V. A. Guzenko, F. Koch, M. Lebugle, F. Marschall, G. Seniutinas, J. Raabe, B. Watts, D. Grolimund, Z. Yin, M. Beye, S. Techert, J. Viefhaus, G. Falkenberg, C. Schroer
Diffractive X-ray Optics for Synchrotrons and Free-Electron Lasers
Microscopy and Microanalysis 24 (Suppl. 2), 2018, 264-265
https://doi.org/10.1017/S1431927618013673

F. Döring, F. Marschall, Z. Yin, B. Rösner, M. Beye, P. Miedema, K. Kubiček, L. Glaser, D. Raiser, J. Soltau, V. A. Guzenko, J. Viefhaus, J. Buck, M. Risch, S. Techert, C. David
1D-Full Field Microscopy of Elastic and Inelastic Scattering with Transmission off-axis Fresnel Zone Plates
Microscopy and Microanalysis 24 (Suppl. 2), 2018, 182-183
https://doi.org/10.1017/S1431927618013260

J. L. Ornelas, B. Rösner, A. Späth, R. H. Fink
STXM_deconv - a MATLAB Script for the Deconvolution of STXM Images
Microscopy and Microanalysis 24 (Suppl. 2), 2018, 120-121
https://doi.org/10.1017/S1431927618012990

B. Rösner, F. Koch, F. Döring, V. A. Guzenko, M. Meyer, J. L. Ornelas, A. Späth, R. H. Fink, S. Stanescu, S. Swaraj, R. Belkhou, B. Watts, J. Raabe, C. David
7 nm Spatial Resolution in Soft X-ray Microscopy
Microscopy and Microanalysis 24 (Suppl. 2), 2018, 270-271
https://doi.org/10.1017/S1431927618013697

P. R. Ribič, B. Rösner, D. Gauthier, E. Allaria, F. Döring, L. Foglia, L. Gianessi, N. Mahne, M. Manfredda, C. Masciovecchio, R. Mincigrucci, N. Mirian, E. Principi, E. Roussel, A. Simoncig, S. Spampinati, C. David, G. de Ninno
Extreme-Ultraviolet Vortices from a Free-Electron Laser
Microscopy and Microanalysis 24 (Suppl. 2), 2018, 292-293
https://doi.org/10.1017/S1431927618013806

R. H. Fink, B. Rösner, X. Du, A. Späth, M. Johnson, T. Hawly, B. Watts, J. Raabe, L. Gregoratti, M. Amati
In-operando soft X-ray microspectroscopy of organic electronic devices
Microscopy and Microanalysis 24 (Suppl. 2), 2018, 424-425
https://doi.org/10.1017/S143192761801437X

R. Fallica, B. Watts, B. Rösner, G. D. Giustina, L. Brigo, G. Brusatin, Y. Ekinci
NEXAFS study of chemical changes in hybrid organic-inorganic resists upon exposure
Nanotechnology 29, 2018, 36LT03
https://doi.org/10.1088/1361-6528/aaccd4

B. Rösner, F. Koch, F. Döring, J. Bosgra, V. A. Guzenko, E. Kirk, M. Meyer, J. L. Ornelas, R. H. Fink, S. Stanescu, S. Swaraj, R. Belkhou, B. Watts, J. Raabe, C. David
Exploiting Atomic Layer Deposition for Fabricating Sub-10 nm X-ray Lenses
Microelectronic Engineering 191, 2018, 91-96
https://doi.org/10.1016/j.mee.2018.01.033

A. Cattoni, D. Mailly, O. Dalstein, M. Faustini, G. Seniutinas, B. Rösner, C. David
Sub-10 nm Electron and Helium Ion Beam Lithography Using a Recently Developed Alumina Resist
Microelectronic Engineering 193, 2018, 18-22
https://doi.org/10.1016/j.mee.2018.02.015

M. Graczyk, A. Cattoni, B. Rösner, G. Seniutinas, A. Kvennefors, A. Löfstrand, D. Mailly, C. David, I. Maximov
Nanoimprint Stamps with Ultra-High Resolution: Optimal Fabrication Techniques
Microelectronic Engineering 190, 2018, 73-78
https://doi.org/10.1016/j.mee.2018.01.008
 

2017

B. Rösner, F. Döring, P. R. Ribič, D. Gauthier, E. Principi, C. Masciovecchio, M. Zangrando, J. Vila-Comamala, G. de Ninno, C. David
High Resolution Beam Profiling of X-ray Free Electron Laser Radiation by Polymer Imprint Development
Optics Express 25, 2017, 30686-30695
https://doi.org/10.1364/OE.25.030686

P. R. Ribič, B. Rösner, D. Gauthier, E. Allaria, F. Döring, L. Foglia, L. Gianessi, N. Mahne, M. Manfredda, C. Masciovecchio, R. Mincigrucci, N. Mirian, E. Principi, E. Roussel, A. Simoncig, S. Spampinati, C. David, G. de Ninno
Extreme-Ultraviolet Vortices from a Free-Electron Laser
Physical Review X 7, 2017, 031036
https://doi.org/10.1103/PhysRevX.7.031036

F. Marschall, Z. Yin, M. Beye, J. Buck, F. Döring, V. A. Guzenko, K. Kubicek, J. Rehanek, D. Raiser, B. Rösner, A. Rothkirch, S. T. Veedu, J. Viefhaus, C. David, S. Techert
Transmission zone plates as analyzers for efficient parallel 2D RIXS-mapping
Scientific Reports 7, 2017, 8849
https://dx.doi.org/10.1038/s41598-017-09052-0

F. Marschall, D. McNally, V. A. Guzenko, B. Rösner, M. Dantz, X. Lu, L. Nue, V. Strocov, T. Schmitt, C. David
Zone plates as imaging analyzers for resonant inelastic x-ray scattering
Optics Express 25, 2017, 15624
https://dx.doi.org/10.1364/OE.25.015624

I. Mohacsi, I. Vartiainen, B. Rösner, M. Guizar-Sicairos, V. A. Guzenko, I. McNulty, R. Winarski, M. V. Holt, C. David
Interlaced zone plate optics for hard X-ray imaging in the 10 nm range
Scientific Reports 7, 2017, 43624
https://dx.doi.org/10.1038/srep43624
 

2016

B. Rösner, U. Schmidt, R. H. Fink
In-operando studies of Ag-TCNQ nanocrystals using Raman and soft x-ray microspectroscopy
XRM Conference Proceedings 849, 2017, 012016
https://dx.doi.org/10.1088/1742-6596/849/1/012016

K. Ran, B. Rösner, B. Butz, R. H. Fink, E. Spiecker
Switching behaviour of individual Ag-TCNQ nanowires: An in situ transmission electron microscopy study
Nanotechnology 27, 2016, 425703
https://dx.doi.org/10.1088/0957-4484/27/42/425703
 

2015

B. Rösner, M. Milek, A. Witt, B. Gobaut, P. Torelli, R. H. Fink, M. M. Khusniyarov
Reversible Photoswitching of a Spin-Crossover Molecular Complex in the Solid State at Room Temperature
Angewandte Chemie Int. Ed. 54, 2015, 12976-12980
https://dx.doi.org/10.1002/anie.201504192

B. Rösner, K. Ran, B. Butz, U. Schmidt, E. Spiecker, R. H. Fink
A microspectroscopic insight into the resistivity switching of individual Ag-TCNQ nanocrystals
Physical Chemistry Chemical Physics 17, 2015, 18278-18281
https://dx.doi.org/10.1039/c5cp02207j

N. Zeilmann, B. Rösner, A. Späth, U. Schmidt, R. H. Fink
Nanomorphology in thin films of acetamide end-functionalised quaterthiophene
Thin Solid Films 583, 2015, 108-114
https://dx.doi.org/10.1016/j.tsf.2015.03.066
 

2014

B. Rösner, D. M. Guldi, J. Chen, A. I. Minett, R. H. Fink
Dispersion and Characterization of Arc Discharge Singe-Walled Carbon Nanotubes - Towards Conducting Transparent Films
Nanoscale 6, 2014, 3695-3703
https://dx.doi.org/10.1039/C3NR05788G

B. Rösner, N. Zeilmann, U. Schmidt, R. H. Fink
Employing microspectroscopy to track charge trapping in operating pentacene OFETs
Organic Electronics 15, 2014, 435-440
https://dx.doi.org/10.1016/j.orgel.2013.12.002
 

2013

B. Rösner, A. Späth, R. H. Fink
The role of solvation effects in the growth of TCNQ-based charge-transfer salts
Journal of Crystal Growth 380, 2013, 34-38
https://dx.doi.org/10.1016/j.jcrysgro.2013.05.031

J. Forster, B. Rösner, R. H. Fink, L. C. Nye, I. Ivanovic-Burmazovic, K. Kastner, J. Tucher, C. Streb
Oxidation-driven self-assembly gives access to high-nuclearity molecular copper vanadium oxide clusters
Chemical Science 4, 2013, 418-424
https://dx.doi.org/10.1039/C2SC20942J
 

2011

J. Forster, B. Rösner, M. M. Khusniyarov, C. Streb
Tuning the light absorption of vanadium clusters
Chemical Communications 47, 2011, 3114-3116
https://dx.doi.org/10.1039/c0cc05536k


Nanoscience Foundries and Fine Analysis

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