TY - JOUR A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray radiation protection aspects during ultrashort laser processing N2 - Ultrashort pulse laser processing of materials allows for precise machining with high accuracy. By increasing the repetition rate to several 100 kHz, laser machining becomes quick and cost-effective. Ultrafast laser processing at high repetition rates and peak intensities above 10^13 W/cm^2 can cause a potential hazard by generation of unwanted x-ray radiation. Therefore, radiation protection must be considered. For 925 fs pulse duration at a center wavelength of 1030 nm, the x-ray emission in air at a repetition rate of 400 kHz was investigated up to a peak intensity of 2.6 × 10^14 W/cm^2. Based on the presented measurements, the properties of potential shielding materials will be discussed. By extending our previous works, a scaling of the x-ray radiation emission to higher peak intensities up to 10^15 W/cm^2 is described, and emitted x-ray doses are predicted. KW - Laser ablation KW - Ultrashort pulse laser processing KW - Laser-induced x-ray emission KW - Radiation protection PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505677 DO - https://doi.org/10.2351/1.5134778 VL - 32 IS - 2 SP - 022004 AN - OPUS4-50567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kunz, C. A1 - Bonse, Jörn A1 - Spaltmann, Dirk A1 - Neumann, C. A1 - Turchanin, A. A1 - Bartolomé, J. F. A1 - Müller, F. A. A1 - Gräf, S. T1 - Tribological performance of metal-reinforced ceramic composites selectively structured with femtosecond laser-induced periodic surface structures N2 - The impact of femtosecond (fs) laser-induced periodic surface structures (LIPSS) on tribological properties was investigated for metal-reinforced ceramic composites (Al2O3-ZrO2-Nb). For this purpose, the metallic niobium (Nb) phase was selectively structured with LIPSS in an air environment with different values of the fs-laser peak fluence by near-infrared fs-laser radiation (λ = 1025 nm, τ = 300 fs, frep = 1 kHz), taking advantage of the different light absorption behavior of ceramic and metal. The tribological performance was evaluated by reciprocating sliding tests in a ball-on-disc configuration using Ringer's solution as lubricant. The surfaces were characterized before and after laser irradiation by optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and by measuring the contact angle with Ringer's solution. The LIPSS formation resulted in an increased wetting of the surface with the lubricant. Moreover, the selectively structured composite surfaces revealed a coefficient of friction significantly reduced by a factor of ~3 when compared to the non-irradiated surface. Furthermore, the formation of a laser-induced oxidation layer was detected with NbO as the most prominent oxidation state. Selectively structured composites with outstanding mechanical properties and enhanced tribological performance are of particular interest for biomedical applications. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Ceramic matrix composites KW - Tribology PY - 2020 DO - https://doi.org/10.1016/j.apsusc.2019.143917 SN - 0169-4332 SN - 1873-5584 VL - 499 IS - 1 SP - 143917 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-49255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cubero, A. A1 - Martínez, E. A1 - Angurel, L.A. A1 - de la Fuente, G.F. A1 - Navarro, R. A1 - Legall, Herbert A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Surface superconductivity changes of niobium sheets by femtosecond laser-induced periodic nanostructures N2 - Irradiation with ultra-short (femtosecond) laser beams enables the generation of sub-wavelength laser-induced periodic surface structures (LIPSS) over large areas with controlled spatial periodicity, orientation, and depths affecting only a material layer on the sub-micrometer scale. This study reports on how fs-laser irradiation of commercially available Nb foil samples affects their superconducting behavior. DC magnetization and AC susceptibility measurements at cryogenic temperatures and with magnetic fields of different amplitude and orientation are thus analyzed and reported. This study pays special attention to the surface superconducting layer that persists above the upper critical magnetic field strength Hc2, and disappears at a higher nucleation field strength Hc3. Characteristic changes were distinguished between the surface properties of the laser-irradiated samples, as compared to the corresponding reference samples (non-irradiated). Clear correlations have been observed between the surface nanostructures and the nucleation field Hc3, which depends on the relative orientation of the magnetic field and the surface patterns developed by the laser irradiation. KW - Niobium KW - Surface superconductivity KW - Laser-induced periodic surface structures (LIPSS) KW - Nanostructures PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518462 DO - https://doi.org/10.3390/nano10122525 SN - 2079-4991 VL - 10(12) IS - Special issue "Laser-generated periodic nanostructures" SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-51846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Déziel, J.-L. A1 - Kirner, Sabrina V. A1 - Siegel, J. A1 - Bonse, Jörn T1 - The role of the laser-induced oxide layer in the formation of laser-induced periodic surface structures N2 - Laser-induced periodic surface structures (LIPSS) are often present when processing solid targets with linearly polarized ultrashort laser pulses. The different irradiation parameters to produce them on metals, semiconductors and dielectrics have been studied extensively, identifying suitable regimes to tailor its properties for applications in the fields of optics, medicine, fluidics and tribology, to name a few. One important parameter widely present when exposing the samples to the high intensities provided by these laser pulses in air environment, that generally is not considered, is the formation of a superficial laser-induced oxide layer. In this paper, we fabricate LIPSS on a layer of the oxidation prone hard-coating material chromium nitride in order to investigate the impact of the laser-induced oxide layer on its formation. A variety of complementary surface analytic techniques were employed, revealing morphological, chemical and structural characteristics of well-known high-spatial frequency LIPSS (HSFL) together with a new type of low-spatial frequency LIPSS (LSFL) with an anomalous orientation parallel to the laser polarization. Based on this input, we performed finite-difference time-domain calculations considering a layered system resembling the geometry of the HSFL along with the presence of a laser-induced oxide layer. The simulations support a scenario that the new type of LSFL is formed at the interface between the laser-induced oxide layer and the non-altered material underneath. These findings suggest that LSFL structures parallel to the polarization can be easily induced in materials that are prone to oxidation. KW - Laser-induced oxide layer KW - Laser-induced periodic surface structures (LIPSS) KW - Surface chemistry KW - Femtosecond laser processing KW - Nanostructuring PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502530 DO - https://doi.org/10.3390/nano10010147 SN - 2079-4991 VL - 10(1) IS - Special issue "Laser-generated periodic nanostructures" SP - 147-1 EP - 147-18 PB - MDPI CY - Basel AN - OPUS4-50253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cubero, A. A1 - Martínez, E. A1 - Angurel, L.A. A1 - de la Fuente, G.F. A1 - Navarro, R. A1 - Legall, Herbert A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Effects of laser-induced periodic surface structures on the superconducting properties of Niobium N2 - It is well known that the use of ultrashort (fs) pulsed lasers can induce the generation of (quasi-) periodic nanostructures (LIPSS, ripples) on the surface of many materials. Such nanostructures have also been observed in sample’s surfaces irradiated with UV lasers with a pulse duration of 300 ps. In this work, we compare the characteristics of these nanostructures on 1-mm and on 25-μm thick niobium sheets induced by 30 fs n-IR and 300 ps UV pulsed lasers. In addition to conventional continuous or burst mode processing configurations, two-dimensional laser beam and line scanning modes have been investigated in this work. The latter allows the processing of large areas with a more uniform distribution of nanostructures at the surface. The influence of the generated nanostructures on the superconducting properties of niobium has also been explored. For this aim, magnetic hysteresis loops have been measured at different cryogenic temperatures to analyse how these laser treatments affect the flux pinning behaviour and, in consequence, the superconductor’s critical current values. It was observed that laser treatments are able to modify the superconducting properties of niobium samples. T2 - E-MRS Spring Meeting 2019 CY - Nice, France DA - 27.05.2019 KW - Superconductivity KW - Laser-induced periodic surface structures (LIPSS) KW - Niobium PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502541 DO - https://doi.org/10.1016/j.apsusc.2019.145140 SN - 0169-4332 SN - 1873-5584 VL - 508 IS - 1 SP - 145140-1 EP - 145140-7 PB - Elsevier CY - Amsterdam AN - OPUS4-50254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Gräf, S. T1 - Ten Open Questions about Laser-Induced Periodic Surface Structures N2 - Laser-induced periodic surface structures (LIPSS) are a simple and robust route for the nanostructuring of solids that can create various surface functionalities featuring applications in optics, medicine, tribology, energy technologies, etc. While the current laser technologies already allow surface processing rates at the level of m2/min, industrial applications of LIPSS are sometimes hampered by the complex interplay between the nanoscale surface topography and the specific surface chemistry, as well as by limitations in controlling the processing of LIPSS and in the long-term stability of the created surface functions. This Perspective article aims to identify some open questions about LIPSS, discusses the pending technological limitations, and sketches the current state of theoretical modelling. Hereby, we intend to stimulate further research and developments in the field of LIPSS for overcoming these limitations and for supporting the transfer of the LIPSS technology into industry. KW - Laser-induced periodic surface structures (LIPSS) KW - Industrial application KW - Functional properties KW - Surface functionalization KW - Modelling PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539503 DO - https://doi.org/10.3390/nano11123326 SN - 2079-4991 VL - 11 IS - 12 SP - 1 EP - 21 PB - MDPI CY - Basel, Switzerland AN - OPUS4-53950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stolzenberg, U. A1 - Schmitt Rahner, M. A1 - Pullner, B. A1 - Legall, Herbert A1 - Bonse, Jörn A1 - Kluge, M. A1 - Ortner, A. A1 - Hoppe, B. A1 - Krüger, Jörg T1 - X-ray emission hazards from ultrashort pulsed laser material processing in an industrial setting N2 - Interactions between ultrashort laser pulses with intensities larger than 10^13 W/cm^2 and solids during material processing can lead to the emission of X-rays with photon energies above 5 keV, causing radiation hazards to operators. A framework for inspecting X-ray emission hazards during laser material processing has yet to be developed. One requirement for conducting radiation protection inspections is using a reference scenario, i.e., laser settings and process parameters that will lead to an almost constant and high level of X-ray emissions. To study the feasibility of setting up a reference scenario in practice, ambient dose rates and photon energies were measured using traceable measurement equipment in an industrial setting at SCHOTT AG. Ultrashort pulsed (USP) lasers with a maximum average power of 220 W provided the opportunity to measure X-ray emissions at laser peak intensities of up to 3.3 × 10^15 W/cm^2 at pulse durations of ~1 ps. The results indicate that increasing the laser peak intensity is insufficient to generate high dose rates. The investigations were affected by various constraints which prevented measuring high ambient dose rates. In this work, a list of issues which may be encountered when performing measurements at USP-laser machines in industrial settings is identified. KW - X-ray emission hazards KW - Ultrashort pulsed laser KW - Radiation protection KW - Industrial applications KW - Protection housing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538632 DO - https://doi.org/10.3390/ma14237163 SN - 1996-1944 VL - 14 SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-53863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Anja A1 - Buchberger, G. A1 - Stifter, D. A1 - Duchoslav, J. A1 - Hertwig, Andreas A1 - Bonse, Jörn A1 - Heitz, J. A1 - Schwibbert, Karin T1 - Spatial Period of Laser-Induced Surface Nanoripples on PET Determines Escherichia coli Repellence N2 - Bacterial adhesion and biofilm formation on surfaces are associated with persistent microbial contamination, biofouling, and the emergence of resistance, thus, calling for new strategies to impede bacterial surface colonization. Using ns-UV laser treatment (wavelength 248 nm and a pulse duration of 20 ns), laser-induced periodic surface structures (LIPSS) featuring different submicrometric periods ranging from ~210 to ~610 nm were processed on commercial poly(ethylene terephthalate) (PET) foils. Bacterial adhesion tests revealed that these nanorippled surfaces exhibit a repellence for E. coli that decisively depends on the spatial periods of the LIPSS with the strongest reduction (~91%) in cell adhesion observed for LIPSS periods of 214 nm. Although chemical and structural analyses indicated a moderate laser-induced surface oxidation, a significant influence on the bacterial adhesion was ruled out. Scanning electron microscopy and additional biofilm studies using a pili-deficient E. coli TG1 strain revealed the role of extracellular appendages in the bacterial repellence observed here. KW - Laser-induced periodic surface structures (LIPSS) KW - Laser processing KW - Polyethylene terephthalate KW - Biofilm formation KW - Cell appendages KW - Biomimetic KW - F pili PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537431 DO - https://doi.org/10.3390/nano11113000 VL - 11 IS - 11 SP - 3000 PB - MDPI AN - OPUS4-53743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, P. A1 - Ihlemann, J. A1 - Bonse, Jörn T1 - Editorial: Special issue "Laser-generated periodic nanostructures" N2 - The study of laser-fabricated periodic nanostructures is one of the leading topics of today’s photonics research. Such structures on the surface of metals, semiconductors, dielectrics, or polymers can generate new material properties with special functionalities. Depending on the specific material parameters and the morphology of the structures, new devices such as microlasers, optical nanoswitches, optical storage devices, sensors or antifraud features can be realized. Furthermore, laser-generated surface textures can be used to improve the tribological properties of surfaces in contact and in relative motion—to reduce friction losses or wear, to modify the wettability or the cell and biofilm growth properties of surfaces through bioinspired laser engineering, for emerging medical applications, or as decoration elements for the refinement of precious goods. This Special Issue “Laser-Generated Periodic Nanostructures” focuses on the latest experimental and theoretical developments and practical applications of laser-generated periodic structures that can be generated in a “self-organized” way (laser-induced periodic surface structures, LIPSS, ripples) or via laser interference-based direct ablation (often referred to as direct laser interference patterning, DLIP). We aimed to attract both academic and industrial researchers in order to collate the current knowledge of nanomaterials and to present new ideas for future applications and new technologies. By 8 August 2021, 22 scientific articles have been published in the Special Issue, see www.mdpi.com/journal/nanomaterials/special_issues/laser-generated_periodic. KW - Laser-induced periodic surface structures (LIPSS) KW - Direct laser interference patterning (DLIP) KW - Surface functionalization KW - Laser ablation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-530980 DO - https://doi.org/10.3390/nano11082054 SN - 2079-4991 VL - 11 IS - 8 SP - 1 EP - 7 PB - MDPI CY - Basel AN - OPUS4-53098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Review of x-ray exposure and safety issues arising from ultra-short pulse laser material processing N2 - Laser processing with ultra-short laser pulses enables machining of materials with high accuracy and throughput. The development of novel laser Technologies with laser pulse repetition rates up to the MHz range opened the way for industrial manufacturing processes. From a radiological point of view this evolution is important, because x-ray radiation can be generated as an unwanted side effect in laser material processing. Even if the emitted x-ray dose per pulse is comparably low, the x-ray dose can become hazardous to health at high laser repetition rates. Therefore, radiation protection must be considered. This article provides an overview on the generation and detection of x-rays in laser material processing, as well as on the handling of this radiation risk in the framework of radiological protection. KW - Ultra-short pulse laser processing KW - Laser-induced x-ray emission KW - Radiation protection PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522376 DO - https://doi.org/10.1088/1361-6498/abcb16 VL - 41 IS - 1 SP - R28 EP - R42 AN - OPUS4-52237 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ayerdi, J. J. A1 - Aginagalde, A. A1 - Llavori, I. A1 - Bonse, Jörn A1 - Spaltmann, Dirk A1 - Zabala, A. T1 - Ball-on-flat linear reciprocating tests: Critical assessment of wear volume determination methods and suggested improvements for ASTM N2 - In the present work it was shown the importance of the correct selection, implementation, and reporting of wear volume computation method and quanitifies the potential errors. KW - Wear KW - Sliding KW - Surface KW - Analysis KW - ASTM KW - D7755-11 PY - 2021 DO - https://doi.org/10.1016/j.wear.2021.203620 VL - 470-471 SP - 3620 AN - OPUS4-52080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Fischer, Daniel A1 - Freiberg, K. A1 - Duwe, M. A1 - Sahre, Mario A1 - Schneider, S. A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Rettenmayr, M. A1 - Beck, Uwe A1 - Undisz, A. A1 - Bonse, Jörn T1 - Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon N2 - Superficial amorphization and re-crystallization of silicon in <111> and <100> orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn. KW - Femtosecond laser KW - Silicon KW - Amorphization KW - Crystallization KW - Spectroscopic imaging ellipsometry PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523687 UR - https://www.mdpi.com/1996-1944/14/7/1651 DO - https://doi.org/10.3390/ma14071651 SN - 1996-1944 VL - 14 IS - 7 SP - 1651-1 EP - 1651-21 PB - MDPI AG CY - Basel, Switzerland AN - OPUS4-52368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Porta-Velilla, L. A1 - Turan, N. A1 - Cubero, Á. A1 - Shao, W. A1 - Li, H. A1 - de la Fuente, G.F. A1 - Martínez, E. A1 - Larrea, Á. A1 - Castro, M. A1 - Koralay, H. A1 - Çavdar, Ş. A1 - Bonse, Jörn A1 - Angurel, L.A. T1 - Highly Regular Hexagonally-Arranged Nanostructures on Ni-W Alloy Tapes upon Irradiation with Ultrashort UV Laser Pulses N2 - Nickel tungsten alloy tapes (Ni—5 at% W, 10 mm wide, 80 µm thick, biaxially textured) used in second-generation high temperature superconductor (2G-HTS) technology were laser-processed in air with ultraviolet ps-laser pulses (355 nm wavelength, 300 ps pulse duration, 250–800 kHz pulse repetition frequency). By employing optimized surface scan-processing strategies, various laser-generated periodic surface structures were generated on the tapes. Particularly, distinct surface microstructures and nanostructures were formed. These included sub-wavelength-sized highly-regular hexagonally-arranged nano-protrusions, wavelength-sized line-grating-like laser-induced periodic surface structures (LIPSS, ripples), and larger irregular pyramidal microstructures. The induced surface morphology was characterized in depth by electron-based techniques, including scanning electron microscopy (SEM), electron back scatter diffraction (EBSD), cross-sectional transmission electron microscopy (STEM/TEM) and energy dispersive X-ray spectrometry (EDS). The in-depth EBSD crystallographic analyses indicated a significant impact of the material initial grain orientation on the type of surface nanostructure and microstructure formed upon laser irradiation. Special emphasis was laid on high-resolution material analysis of the hexagonally-arranged nano-protrusions. Their formation mechanism is discussed on the basis of the interplay between electromagnetic scattering effects followed by hydrodynamic matter re-organization after the laser exposure. The temperature stability of the hexagonally-arranged nano-protrusion was explored in post-irradiation thermal annealing experiments, in order to qualify their suitability in 2G-HTS fabrication technology with initial steps deposition temperatures in the range of 773–873 K. KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser processing KW - Hexagonally-arranged nano-protrusions KW - Second-generation high temperature superconductor technology KW - Electron microscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552551 DO - https://doi.org/10.3390/nano12142380 SN - 2079-4991 VL - 12 IS - 14 SP - 1 EP - 23 PB - MDPI CY - Basel, Switzerland AN - OPUS4-55255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lifka, S. A1 - Harsányi, K. A1 - Baumgartner, E. A1 - Pichler, L. A1 - Baiko, D. A1 - Wasmuth, Karsten A1 - Heitz, J. A1 - Meyer, M. A1 - Joel, A.-C. A1 - Bonse, Jörn A1 - Baumgartner, W. ED - Mail, M. T1 - Laser-processed antiadhesive bionic combs for handling nanofibers inspired by nanostructures on the legs of cribellate spiders N2 - Nanofibers are drawing the attention of engineers and scientists because their large surface-to-volume ratio is favorable for applications in medicine, filter technology, textile industry, lithium-air batteries, and optical sensors. However, when transferring nanofibers to a technical product in the form of a random network of fibers, referred to as nonwoven fabric, the stickiness of the freshly produced and thus fragile nanofiber nonwoven remains a problem. This is mainly because nanofibers strongly adhere to any surface because of van der Waals forces. In nature, there are animals that are actually able to efficiently produce, process, and handle nanofibers, namely cribellate spiders. For that, the spiders use the calamistrum, a comb-like structure of modified setae on the metatarsus of the hindmost (fourth) legs, to which the 10–30 nm thick silk nanofibers do not stick due to a special fingerprint-like surface nanostructure. In this work, we present a theoretical model of the interaction of linear nanofibers with a sinusoidally corrugated surface. This model allows for a prediction of the adhesive interaction and, thus, the design of a suitable surface structure to prevent sticking of an artificially nonwoven of nanofibers. According to the theoretical prediction, a technical analogon of the nanoripples was produced by ultrashort pulse laser processing on different technically relevant metal surfaces in the form of so-called laser-induced periodic surface structures (LIPSS). Subsequently, by means of a newly established peel-off test, the adhesion of an electrospun polyamide fiber-based nonwoven was quantified on such LIPSS-covered aluminium alloy, steel, and titanium alloy samples, as well as on polished (flat) control samples as reference and, additionally, on samples with randomly rough surfaces. The latter revealed that the adhesion of electrospun nanofiber nonwoven is significantly lowered on the nanostructured surfaces compared with the polished surfaces. KW - Laser-induced periodic surface structures (LIPSS) KW - Cribellate spiders KW - Calamistrum KW - Electrospinning KW - Nanofibers PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-561799 DO - https://doi.org/10.3762/bjnano.13.105 SN - 2190-4286 VL - 13 SP - 1268 EP - 1283 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, M. AN - OPUS4-56179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Katrin A1 - Schmitt Rahner, M. A1 - Stolzenberg, U. A1 - Kraft, Sebastian A1 - Bonse, Jörn A1 - Feist, C. A1 - Albrecht, D. A1 - Pullner, B. A1 - Krüger, Jörg T1 - Worst-case X-ray photon energies in ultrashort pulse laser processing N2 - Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 10^13 W/cm^2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 µm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances ranging from 7.3 × 10^13 W/cm^2 up to 3.0 × 10^14 W/cm^2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 10^14 W/cm^2. KW - Ultrashort pulsed laser KW - X-ray emission KW - X-ray spectrum KW - X-ray energies KW - Radiation protection PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-566176 DO - https://doi.org/10.3390/ma15248996 VL - 15 IS - 24 SP - 1 EP - 17 PB - MDPI AN - OPUS4-56617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Structuring of thin films by ultrashort laser pulses N2 - Modern life and global communication would not be possible without technologically tailored thin films; they are omnipresent in daily life applications. In most cases, the films are deposited entirely at the carrying substrates in a specific processing step of the device or sample. In some cases, however, removal or modification must be performed locally, i.e., site-controlled and material selective through an additional laser processing step. For that ultrashort laser pulses with durations in the femtosecond and picosecond range can provide unique advantages and capabilities in industrially scalable schemes. This article reviews the current state of the research and corresponding industrial transfer related to the structuring of thin films by ultrashort pulsed lasers. It focuses on the pertinent historic developments, reveals the relevant physical and chemical effects, explores the ultimate limits, and discusses selected industrial and scientific applications. KW - Thin films KW - Laser processing KW - Ultrashort lasers KW - Laser damage KW - Femtosecond laser ablation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565732 DO - https://doi.org/10.1007/s00339-022-06229-x SN - 0947-8396 SN - 1432-0630 VL - 129 IS - 1 SP - 1 EP - 38 PB - Springer CY - Berlin AN - OPUS4-56573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolff, M. A1 - Wonneberger, R. A1 - Freiberg, K.E. A1 - Hertwig, Andreas A1 - Bonse, Jörn A1 - Giebeler, L. A1 - Koitzsch, A. A1 - Kunz, C. A1 - Weber, H. A1 - Hufenbach, J.K. A1 - Müller, F.A. A1 - Gräf, S. T1 - Formation of laser-induced periodic surface structures on Zr-based bulk metallic glasses with different chemical composition N2 - Bulk metallic glasses (BMG) are amorphous metal alloys known for their unique physical and mechanical properties. In the present study, the formation of femtosecond (fs) laser-induced periodic surface structures (LIPSS) on the Zr-based BMGs Zr46Cu46Al8, Zr61Cu25Al12Ti2, Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit105) and Zr57Cu15.4Al10Ni12.6Nb5 (Vit106) was investigated as a function of their different chemical composition. For this purpose, LIPSS were generated on the sample surfaces in an air environment by fs-laser irradiation (λ = 1025 nm, τ = 300 fs, frep = 100 kHz). The surface topography was characterized by scanning electron microscopy and atomic force microscopy. Moreover, the impact of LIPSS formation on the structure and chemical surface composition was analyzed before and after fs-laser irradiation by X-ray diffraction and X-ray photoelectron spectroscopy as well as by transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. Despite the different chemical composition of the investigated BMGs, the fs-laser irradiation resulted in almost similar properties of the generated LIPSS patterns. In the case of Zr61Cu25Al12Ti2, Vit105 and Vit106, the surface analysis revealed the preservation of the amorphous state of the materials during fs-laser irradiation. The study demonstrated the presence of a native oxide layer on all pristine BMGs. In addition, fs-laser irradiation results in the formation of laser-induced oxide layers of larger thickness consisting of an amorphous ZrAlCu-oxide. The precise laser-structuring of BMG surfaces on the nanoscale provides a versatile alternative to thermoplastic forming of BMG surfaces and is of particular interest for the engineering of functional material surfaces. KW - Bulk metallic glasses KW - Femtosecond laser KW - Laser-induced periodic surface structures (LIPSS) KW - Chemical analysis KW - Oxidation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581799 DO - https://doi.org/10.1016/j.surfin.2023.103305 SN - 2468-0230 VL - 42 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-58179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwibbert, Karin A1 - Richter, Anja M. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Laser-Textured Surfaces: A Way to Control Biofilm Formation? N2 - Bacterial biofilms pose serious problems in medical and industrial settings. One of the major societal challenges lies in the increasing resistance of bacteria against biocides used in antimicrobial treatments, e.g., via overabundant use in medicine, industry, and agriculture or cleaning and disinfection in private households. Hence, new efficient bacteria-repellent strategies avoiding the use of biocides are strongly desired. One promising route to achieve bacteria-repellent surfaces lies in the contactless and aseptic large-area laser-processing of technical surfaces. Tailored surface textures, enabled by different laser-processing strategies that result in topographic scales ranging from nanometers to micrometers may provide a solution to this challenge. This article presents a current state-of-the-art review of laser-surface subtractive texturing approaches for controlling the biofilm formation for different bacterial strains and in different environments. Based on specific properties of bacteria and laser-processed surfaces, the challenges of anti-microbial surface designs are discussed, and future directions will be outlined. KW - Antibacterial surfaces KW - Biofilms KW - Laser processing KW - Laser-induced periodic surface structures (LIPSS) KW - Microbial adhesions PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588260 DO - https://doi.org/10.1002/lpor.202300753 SN - 1863-8899 SP - 1 EP - 41 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-58826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kraft, Sebastian A1 - Schille, J. A1 - Bonse, Jörn A1 - Löschner, U. A1 - Krüger, Jörg T1 - X‑ray emission during the ablative processing of biological materials by ultrashort laser pulses N2 - The ablative laser processing with ultrashort pulsed laser beams may cause secondary emission of hazardous X-rays. While the effect has recently been proven to be considered in working safety regulations when processing technical materials, such as metals, the X-ray emission rates during the ablative processing of biological tissue materials are widely unexplored yet. Therefore, biological materials like water, isotonic saline solution, pig eyes, and human teeth were ablated with ultrashort laser pulses of 1030 nm wavelength, 600 fs pulse duration and 5 kHz pulse repetition rate, aiming to mimic typical surgery situations. Simultaneously, in-situ X-ray dose rate measurements were performed at a short distance from the plasma to display potential X-ray emission. For all four studied biological materials, our measurements prove the secondary emission of laser-induced X-rays. KW - Ultrashort pulsed laser KW - Laser-induced X-ray emission KW - Ophthalmology KW - Dentistry KW - Secondary hazard PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569960 DO - https://doi.org/10.1007/s00339-023-06440-4 SN - 0947-8396 VL - 129 IS - 3 SP - 1 EP - 8 PB - Springer AN - OPUS4-56996 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Costache, F. A1 - Valette, S. A1 - Bonse, Jörn T1 - Editorial: Special Issue “Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif” N2 - The Special Issue “Dynamics and Processes at Laser-irradiated Surfaces” is dedicated to the 70th birthday of Jürgen Reif, retired full professor, former Chair of Experimental Physics II of the Faculty of Physics of the Brandenburg University of Technology Cottbus—Senftenberg in Germany. KW - Laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Surface functionalization KW - Femtosecond laser PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569482 DO - https://doi.org/10.3390/nano13030611 SN - 2079-4991 VL - 13 IS - 3 SP - 1 EP - 3 PB - MDPI CY - Basel AN - OPUS4-56948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Editorial: Special Issue “Advanced Pulse Laser Machining Technology" N2 - “Advanced Pulse Laser Machining Technology” is a rapidly growing field that can be tailored to special industrial and scientific applications. This is significantly driven by the availability of high-repetition-rate laser sources and novel beam delivery concepts. KW - Editorial KW - Pulse Laser KW - Laser Machining KW - Ultrashort laser pulses PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568410 DO - https://doi.org/10.3390/ma16020819 SN - 1996-1944 VL - 16 IS - 2 SP - 1 EP - 4 PB - MDPI CY - Basel AN - OPUS4-56841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Porta-Velilla, L. A1 - Martínez, E. A1 - Frechilla, A. A1 - Castro, M. A1 - de la Fuente, G. F. A1 - Bonse, Jörn A1 - Angurel, L. A. T1 - Grain orientation, angle of incidence, and beam polarization effects on ultraviolet 300 ps-laser-induced nanostructures on 316L stainless steel N2 - Laser-induced periodic surface structures (LIPSS) represent a unique route for functionalizing materials through the fabrication of surface nanostructures. Commercial AISI 316L stainless steel (SS316L) surfaces are laser treated by ultraviolet 300 ps laser pulses in a laser line scanning (LLS) approach. Processing parameters are optimized (pulse energy of 2.08 µJ, pulse repetition frequency of 300 kHz, and suitable laser scan and sample displacement rates) for the generation of low spatial frequency LIPSS over a large 25 × 25 mm2 area. Different angles of incidence of the laser radiation (0°, 30°, and 45°) and different linear laser beam polarizations (s and p) produce a plethora of rippled surface morphologies at distinct grains. Scanning electron microscopy and 2D Fourier transforms, together with calculations of the optical energy deposited at the treated surfaces using Sipe's first-principles electromagnetic scattering theory, are used to study and analyze in detail these surface morphologies. Combined with electron backscattering diffraction, analyses allow associating site-selectively various laser-induced-surface morphologies with the underlying crystalline grain orientation. Resulting grain orientation maps reveal a strong impact of the grain crystallographic orientation on LIPSS formation and point toward possible strategies, like multi-step processes, for improving the manufacturing of LIPSS and their areal coverage of polycrystalline technical materials. KW - Laser-induced periodic surface structures (LIPSS) KW - Steel KW - Grain orientation KW - Electron backscattering diffraction (EBSD) KW - Laser processing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588929 DO - https://doi.org/10.1002/lpor.202300589 SN - 1863-8899 SP - 1 EP - 21 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-58892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Sokolowski‐Tinten, Klaus T1 - Probing Laser‐Driven Structure Formation at Extreme Scales in Space and Time N2 - Irradiation of solid surfaces with high intensity, ultrashort laser pulses triggers a variety of secondary processes that can lead to the formation of transient and permanent structures over a large range of length scales from mm down to the nano‐range. One of the most prominent examples are LIPSS – Laser‐Induced Periodic Surface Structures. While LIPSS have been a scientific evergreen for of almost 60 years, experimental methods that combine ultrafast temporal with the required nm spatial resolution have become available only recently with the advent of short pulse, short wavelength free electron lasers. Here, the current status and future perspectives in this field are discussed by exploiting the unique possibilities of these 4th‐generation light sources to address by time‐domain experimental techniques the fundamental LIPSS‐question, namely why and how laser irradiation can initiate the transition of a “chaotic” (rough) surface from an aperiodic into a periodic structure. KW - Laser-induced periodic surface structures (LIPSS) KW - Free electron laser KW - Pump-probe experiments KW - Time-resolved scattering KW - Capillary waves PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595048 DO - https://doi.org/10.1002/lpor.202300912 SN - 1863-8899 VL - 18 SP - 1 EP - 11 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-59504 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, Y. A1 - Gruner, A. A1 - Aboud, D. G. K. A1 - Bonse, Jörn A1 - Schille, J. A1 - Loeschner, U. A1 - Kietzig, A.-M. T1 - Polarization effects on laser-inscribed angled micro-structures N2 - The polarization of the laser beam exhibits more substantial differences in laser micromachining as the angle of incidence deviates from zero. In the reported work, our focus was to explore the effects of circularly, p- and s-polarized laser on angled ultrashort pulse laser micromachining of micropillar arrays. The examination encompassed laser process factors, including angles of incidence, microstructure dimensions, and inter-pillar spacing. A comparison between the resulting structures demonstrated that p-polarized laser beam was the most efficient in material removal in angled laser micromachining, followed by circularly polarized laser. While the s-polarized beam exhibited the lowest ablation efficiency among the three. Such distinction is mainly attributed to the distinguishing reflectivity of the three states of polarization on tilted planes. The development of structural heights during ablation processes was examined, and potential defects in laser processing methodologies were interpreted. The dependency of structural heights on inter-pillar spacing was analyzed. This study bridges the gap between existing studies on angled ultrashort pulse laser machining and the influences of polarization on laser machining. The comparison between structures produced using laboratory-scale and industrial-scale laser systems also yielded pertinent recommendations for facilitating a smooth transition of angled laser micromachining from laboratory-scale research to industrial applications. KW - Laser processing KW - Laser-induced periodic surface structures (LIPSS) KW - Microstructures KW - Nanostructures PY - 2024 UR - https://www.sciencedirect.com/science/article/pii/S0169433223028714 DO - https://doi.org/10.1016/j.apsusc.2023.159191 SN - 0169-4332 VL - 649 SP - 1 EP - 15 PB - Elsevier AN - OPUS4-59329 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, Heike A1 - Knigge, Xenia A1 - Knapic, D. A1 - Weise, Matthias A1 - Sahre, Mario A1 - Hertwig, Andreas A1 - Sacco, A. A1 - Rossi, A. M. A1 - Radnik, Jörg A1 - Müller, Kai A1 - Wasmuth, Karsten A1 - Krüger, Jörg A1 - Hassel, A. W. A1 - Hodoroaba, Vasile-Dan A1 - Bonse, Jörn T1 - Picosecond laser processing of hierarchical micro–nanostructures on titanium alloy upon pre- and postanodization: morphological, structural, and chemical effects N2 - Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone-forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre- and postanodization for two different characteristic microspikes covered by nanometric laser-induced periodic surface structures on Ti–6Al–4V upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X-ray diffraction, and micro-Raman spectroscopy, as well as near-surface chemical analyses by X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near-surface oxidation that may affect the different cell growth behavior for pre- or postanodized medical implants. T2 - 2023 E-MRS Spring Meeting, Symposium L "Making light matter: lasers in material sciences and photonics" CY - Strasbourg, France DA - 29.05.2023 KW - Hierarchical micro-nanostructures KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser pulses KW - Ti-6Al-4V alloy KW - X-ray photoelectron spectroscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601962 DO - https://doi.org/10.1002/pssa.202300920 SN - 1862-6319 SP - 1 EP - 11 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-60196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -