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Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor...
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Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 41168

Special Issue Editors

Dr. Florenta Costache

E-Mail Website
Guest Editor
Fraunhofer Institute for Photonic Microsystems, IPMS, Maria-Reiche-Str. 2, 01109 Dresden, Germany
Interests: laser–matter interaction; silicon and silicon-organic-hybrid photonics; femtosecond laser processes; functional nanostructures; micro-optics; actuators; (bio)sensors and surface functionalization; semiconductor technology
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Stéphane Valette

E-Mail Website
Guest Editor
Ecole Centrale de Lyon, LTDS, 36 avenue Guy de Collongue, CEDEX, 69134 Ecully, France
Interests: biomimetics; surface and interface science; surface functionalization; surface texturing; femtosecond laser processes; wettability; super-hydrophobicity; topography; complex surfaces; tribology; Lattice–Boltzmann method
Special Issues, Collections and Topics in MDPI journals
Dr. Jörn Bonse

E-Mail Website
Guest Editor
Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
Interests: laser–matter interaction; femtosecond laser technology; laser ablation; ultrashort laser pulses and applications; micro- and nano-structured surfaces; surface functionalization by of laser-textured surfaces; biomimetics; ultrafast microscopy; time-resolved spectroscopy; plasmonics; laser processes in photovoltaics; laser safety
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue 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.

In recognition of his long-lasting scientific contributions and research lines, the topics of this Themed Special Issue are defined and include nonlinear optics and photonics, semiconductor technology, optical spectroscopy, surface dynamics, in situ measurement techniques, experimental and theoretical investigations of laser–matter interaction, applications of surface functionalization through laser-induced micro- and nanostructures, laser processing of polymers, numerical modeling of surface processes, etc.

For more than 25 years, the work of Prof. Reif has been very actively devoted to the study of fundamental mechanisms, dynamics, and applications of nano- and micrometer-scale laser-induced periodic surface structures (LIPSS), with a focus on self-organization processes. His contributions have revived and strongly stimulated the competition of the two main approaches (“schools”) to explain LIPSS, either via matter reorganization or via coherent electromagnetic scattering effects, and investigated their dynamics and applications in the fields of surface wetting and tribology.

Because these scientific areas lie at the boundaries between nonlinear optics and spectroscopy, surface and solid state physics, materials science and nanotechnology, and in honor and recognition of Prof. Reif’s scientific contributions, this joint Special Issue of the two journals Molecules and Nanomaterials welcomes the submission of original research manuscripts, perspectives articles, or reviews related to "Dynamics and Processes at Laser-irradiated Surfaces".

Accepted papers are published in the joint Special Issue in Nanomaterials or Molecules (https://0-www-mdpi-com.brum.beds.ac.uk/journal/molecules/special_issues/jurgen_reif).

Dr. Florenta Costache
Prof. Dr. Stéphane Valette
Dr. Jörn Bonse
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Laser–matter interaction
  • Nonlinear optics and photonics
  • Surface dynamics
  • Laser-induced periodic surface structures (LIPSS), ripples
  • Self-organization
  • Surface functionalization and applications of laser-textured surfaces
  • Polymer processing
  • Micro- and nanotechnology
  • Semiconductor technology
  • Surface wetting and tribology
  • In situ optical measurement techniques
  • Numerical modeling of surface processes

Published Papers (18 papers)

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Editorial

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3 pages, 223 KiB  
Editorial
Special Issue “Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif”
by Florenta Costache, Stéphane Valette and Jörn Bonse
Nanomaterials 2023, 13(3), 611; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13030611 - 03 Feb 2023
Viewed by 953
Abstract
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 [...] Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)

Research

Jump to: Editorial, Review, Other

20 pages, 7507 KiB  
Article
Effect of Texturing Environment on Wetting of Biomimetic Superhydrophobic Surfaces Designed by Femtosecond Laser Texturing
by Salomé Basset, Guillaume Heisbourg, Alina Pascale-Hamri, Stéphane Benayoun and Stéphane Valette
Nanomaterials 2022, 12(18), 3099; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12183099 - 07 Sep 2022
Cited by 9 | Viewed by 1693
Abstract
Inspired by Euphorbia leaves, micrometric pillars are designed on 316L stainless steel surfaces using a femtosecond laser to achieve superhydrophobicity. In this study, we focus on wetting behavior evolution as a function of time and chemical environment. Two types of texturing designs are [...] Read more.
Inspired by Euphorbia leaves, micrometric pillars are designed on 316L stainless steel surfaces using a femtosecond laser to achieve superhydrophobicity. In this study, we focus on wetting behavior evolution as a function of time and chemical environment. Two types of texturing designs are performed: the laser texturing of micrometric square pillars, and the laser texturing of micrometric square pillars whose tops were irradiated using various fluences to obtain a different topography on the nanometric scale. Two laser texturing environments are considered in both cases: a CO2 flow and ambient air. The main result is that 250 days after laser texturing, steady-state contact angles (SSCA) were above 130° no matter what the environment was. We also study the effect of regular wetting over time. Comparing the results of surfaces for which wetting over time was conducted and that of the undisturbed surfaces for 250 days demonstrates that performing wetting measurements when the surface is not stable led to major changes in droplet behavior. Our surfaces have a unique wettability in which droplets are in an intermediate state. Finally, using a CO2 flow did not help reach higher SSCA, but it limited the effect of regular wetting measurements. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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16 pages, 10763 KiB  
Article
Formation of Nano- and Micro-Scale Surface Features Induced by Long-Range Femtosecond Filament Laser Ablation
by Joerg Schille, Jose R. Chirinos, Xianglei Mao, Lutz Schneider, Matthias Horn, Udo Loeschner and Vassilia Zorba
Nanomaterials 2022, 12(14), 2493; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12142493 - 20 Jul 2022
Cited by 1 | Viewed by 1790
Abstract
In this work, we study the characteristics of femtosecond-filament-laser–matter interactions and laser-induced periodic surface structures (LIPSS) at a beam-propagation distance up to 55 m. The quantification of the periodicity of filament-induced self-organized surface structures was accomplished by SEM and AFM measurements combined with [...] Read more.
In this work, we study the characteristics of femtosecond-filament-laser–matter interactions and laser-induced periodic surface structures (LIPSS) at a beam-propagation distance up to 55 m. The quantification of the periodicity of filament-induced self-organized surface structures was accomplished by SEM and AFM measurements combined with the use of discrete two-dimensional fast Fourier transform (2D-FFT) analysis, at different filament propagation distances. The results show that the size of the nano-scale surface features increased with ongoing laser filament processing and, further, periodic ripples started to form in the ablation-spot center after irradiation with five spatially overlapping pulses. The effective number of irradiating filament pulses per spot area affected the developing surface texture, with the period of the low spatial frequency LIPSS reducing notably at a high pulse number. The high regularity of the filament-induced ripples was verified by the demonstration of the angle-of-incidence-dependent diffraction of sunlight. This work underlines the potential of long-range femtosecond filamentation for energy delivery at remote distances, with suppressed diffraction and long depth focus, which can be used in biomimetic laser surface engineering and remote-sensing applications. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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23 pages, 10523 KiB  
Article
Highly Regular Hexagonally-Arranged Nanostructures on Ni-W Alloy Tapes upon Irradiation with Ultrashort UV Laser Pulses
by Luis Porta-Velilla, Neslihan Turan, Álvaro Cubero, Wei Shao, Hongtao Li, Germán F. de la Fuente, Elena Martínez, Ángel Larrea, Miguel Castro, Haluk Koralay, Şükrü Çavdar, Jörn Bonse and Luis A. Angurel
Nanomaterials 2022, 12(14), 2380; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12142380 - 12 Jul 2022
Cited by 10 | Viewed by 1851
Abstract
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). [...] Read more.
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. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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16 pages, 6869 KiB  
Article
Picosecond Laser-Ablated Nanoparticles Loaded Filter Paper for SERS-Based Trace Detection of Thiram, 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX), and Nile Blue
by Chandu Byram, Jagannath Rathod, Sree Satya Bharati Moram, Akkanaboina Mangababu and Venugopal Rao Soma
Nanomaterials 2022, 12(13), 2150; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12132150 - 22 Jun 2022
Cited by 10 | Viewed by 1947
Abstract
Recently, filter paper (FP)-based surface-enhanced Raman scattering (SERS) substrates have stimulated significant attention owing to their promising advantages such as being low-cost, easy to handle, and practically suitable for real-field applications in comparison to the solid-based substrates. Herein, a simple and versatile approach [...] Read more.
Recently, filter paper (FP)-based surface-enhanced Raman scattering (SERS) substrates have stimulated significant attention owing to their promising advantages such as being low-cost, easy to handle, and practically suitable for real-field applications in comparison to the solid-based substrates. Herein, a simple and versatile approach of laser-ablation in liquid for the fabrication of silver (Ag)-gold (Au) alloy nanoparticles (NPs). Next, the optimization of flexible base substrate (sandpaper, printing paper, and FP) and the FP the soaking time (5–60 min) was studied. Further, the optimized FP with 30 min-soaked SERS sensors were exploited to detect minuscule concentrations of pesticide (thiram-50 nM), dye (Nile blue-5 nM), and an explosive (RDX-1,3,5-Trinitroperhydro-1,3,5-triazine-100 nM) molecule. Interestingly, a prominent SERS effect was observed from the Au NPs exhibiting satisfactory reproducibility in the SERS signals over ~1 cm2 area for all of the molecules inspected with enhancement factors of ~105 and relative standard deviation values of <15%. Furthermore, traces of pesticide residues on the surface of a banana and RDX on the glass slide were swabbed with the optimized FP substrate and successfully recorded the SERS spectra using a portable Raman spectrometer. This signifies the great potential application of such low-cost, flexible substrates in the future real-life fields. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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14 pages, 5181 KiB  
Article
Interface Adhesion Property and Laser Ablation Performance of GAP-PET Double-Layer Tape with Plasma Treatment
by Sibo Wang, Bangdeng Du, Baoyu Xing, Yanji Hong, Ying Wang, Baosheng Du, Yongzan Zheng, Jifei Ye and Chenglin Li
Nanomaterials 2022, 12(11), 1827; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12111827 - 26 May 2022
Cited by 3 | Viewed by 1457
Abstract
In the field of laser ablation micro-propulsion, the property of double-layer tape has significant impact on the propulsion performance. In this paper, low temperature plasma was used to treat the surface of polyethylene terephthalate (PET) to improve its adhesion with energetic polymer. The [...] Read more.
In the field of laser ablation micro-propulsion, the property of double-layer tape has significant impact on the propulsion performance. In this paper, low temperature plasma was used to treat the surface of polyethylene terephthalate (PET) to improve its adhesion with energetic polymer. The PET surface pre- and post-plasma treatment was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the enhancement mechanism of the interface adhesion was discussed. In addition, the ablation performance of the double-layer tape after the plasma treatment was studied. The results showed that the plasma etching effect increased the root mean square roughness of the PET surface from 1.74 nm to 19.10 nm. In addition, after the plasma treatment, the number of C–OH/COOH bonds and O=C–O bonds increased, which also greatly improved the adhesion between the PET and energetic polymers. In the optimization of the ablation performance, the optimal laser pulse width was about 200 μs. The optimal values of the specific impulse (Isp), impulse coupling coefficient (Cm), and ablation efficiency (η) were 390.65 s, 250.82 μN/W, and 48.01%, respectively. The optimization of the adhesion of the double-layer tape and the ablation performance lay the foundation for the engineering application of laser ablation micro-thrusters. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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9 pages, 2072 KiB  
Article
Femtosecond Laser-Assisted Formation of Hybrid Nanoparticles from Bi-Layer Gold–Silicon Films for Microscale White-Light Source
by Sergei Koromyslov, Eduard Ageev, Ekaterina Ponkratova, Artem Larin, Ivan Shishkin, Denis Danilov, Ivan Mukhin, Sergey Makarov and Dmitry Zuev
Nanomaterials 2022, 12(10), 1756; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12101756 - 21 May 2022
Cited by 4 | Viewed by 1970
Abstract
It is very natural to use silicon as a primary material for microelectronics. However, silicon application in nanophotonics is limited due to the indirect gap of its energy band structure. To improve the silicon emission properties, it can be combined with a plasmonic [...] Read more.
It is very natural to use silicon as a primary material for microelectronics. However, silicon application in nanophotonics is limited due to the indirect gap of its energy band structure. To improve the silicon emission properties, it can be combined with a plasmonic part. The resulting metal–dielectric (hybrid) nanostructures have shown their excellence compared to simple metallic dielectric nanostructures. Still, in many cases, the fabrication of such structures is time consuming and quite difficult. Here, for the first time, we demonstrate a single-step and lithography-free laser-induced dewetting of bi-layer nanoscale-thickness gold–silicon films supported by a glass substrate to produce hybrid nanoparticles. For obtaining hybrid nanoparticles, we study nonlinear photoluminescence by mapping their optical response and morphology by scanning electron microscopy. This method can be used for the fabrication of arrays of hybrid nanoparticles providing white-light photoluminescence with a good control of their microscopic sizes and position. The developed approach can be useful for a wide range of photonic applications including the all-optical data processing and storage where miniaturization down to micro- and nanoscale together with an efficiency increase is of high demand. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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15 pages, 589 KiB  
Article
Influence of Electronic Non-Equilibrium on Energy Distribution and Dissipation in Aluminum Studied with an Extended Two-Temperature Model
by Markus Uehlein, Sebastian T. Weber and Baerbel Rethfeld
Nanomaterials 2022, 12(10), 1655; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12101655 - 12 May 2022
Cited by 9 | Viewed by 2129
Abstract
When an ultrashort laser pulse excites a metal surface, only a few of all the free electrons absorb a photon. The resulting non-equilibrium electron energy distribution thermalizes quickly to a hot Fermi distribution. The further energy dissipation is usually described in the framework [...] Read more.
When an ultrashort laser pulse excites a metal surface, only a few of all the free electrons absorb a photon. The resulting non-equilibrium electron energy distribution thermalizes quickly to a hot Fermi distribution. The further energy dissipation is usually described in the framework of a two-temperature model, considering the phonons of the crystal lattice as a second subsystem. Here, we present an extension of the two-temperature model including the non-equilibrium electrons as a third subsystem. The model was proposed initially by E. Carpene and later improved by G.D. Tsibidis. We introduce further refinements, in particular, a temperature-dependent electron–electron thermalization time and an extended energy interval for the excitation function. We show results comparing the transient energy densities as well as the energy-transfer rates of the original equilibrium two-temperature description and the improved extended two-temperature model, respectively. Looking at the energy distribution of all electrons, we find good agreement in the non-equilibrium distribution of the extended two-temperature model with results from a kinetic description solving full Boltzmann collision integrals. The model provides a convenient tool to trace non-equilibrium electrons at small computational effort. As an example, we determine the dynamics of high-energy electrons observable in photo-electron spectroscopy. The comparison of the calculated spectral densities with experimental results demonstrates the necessity of considering electronic non-equilibrium distributions and electron–electron thermalization processes in time- and energy-resolved analyses. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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22 pages, 3415 KiB  
Article
Ultrafast Laser Material Damage Simulation—A New Look at an Old Problem
by Simin Zhang, Carmen Menoni, Vitaly Gruzdev and Enam Chowdhury
Nanomaterials 2022, 12(8), 1259; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12081259 - 08 Apr 2022
Cited by 12 | Viewed by 2234
Abstract
The chirped pulse amplification technique has enabled the generation of pulses of a few femtosecond duration with peak powers multi-Tera and Peta–Watt in the near infrared. Its implementation to realize even shorter pulse duration, higher energy, and higher repetition rate laser systems relies [...] Read more.
The chirped pulse amplification technique has enabled the generation of pulses of a few femtosecond duration with peak powers multi-Tera and Peta–Watt in the near infrared. Its implementation to realize even shorter pulse duration, higher energy, and higher repetition rate laser systems relies on overcoming the limitations imposed by laser damage of critical components. In particular, the laser damage of coatings in the amplifiers and in post-compression optics have become a bottleneck. The robustness of optical coatings is typically evaluated numerically through steady-state simulations of electric field enhancement in multilayer stacks. However, this approach cannot capture crucial characteristics of femtosecond laser induced damage (LID), as it only considers the geometry of the multilayer stack and the optical properties of the materials composing the stack. This approach neglects that in the interaction of an ultrashort pulse and the materials there is plasma generation and associated material modifications. Here, we present a numerical approach to estimate the LID threshold of dielectric multilayer coatings based on strong field electronic dynamics. In this dynamic scheme, the electric field propagation, photoionization, impact ionization, and electron heating are incorporated through a finite-difference time-domain algorithm. We applied our method to simulate the LID threshold of bulk fused silica, and of multilayer dielectric mirrors and gratings. The results are then compared with experimental measurements. The salient aspects of our model, such as the implementation of the Keldysh photoionization model, the impact ionization model, the electron collision model for ‘low’-temperature, dense plasma, and the LID threshold criterion for few-cycle pulses are discussed. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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15 pages, 3708 KiB  
Article
Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal
by Igor Gvozdovskyy, Zoya Kazantseva, Simon Schwarz and Ralf Hellmann
Nanomaterials 2022, 12(3), 508; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12030508 - 01 Feb 2022
Cited by 2 | Viewed by 1860
Abstract
In this study, we report on the alignment properties of nematic liquid crystals on various transparent structured sapphire layers formed by laser-induced periodic surface structures (LIPSS). One-dimensional LIPSS (1D-LSFL) are generated by infrared femtosecond laser pulses along parallel lines covering an area of [...] Read more.
In this study, we report on the alignment properties of nematic liquid crystals on various transparent structured sapphire layers formed by laser-induced periodic surface structures (LIPSS). One-dimensional LIPSS (1D-LSFL) are generated by infrared femtosecond laser pulses along parallel lines covering an area of 5 × 5 mm2, with a line spacing that is varied between 7 and 17 µm. These periodic structures, employed as alignment layers, have a spatial periodicity of about 980 nm, a modulation depth of about 100 nm, and exhibit a high quality due to being characterized by a high degree of homogeneity and parallelism of the structured features. It is found that such alignment layers of the sapphire surface lead to a decreasing azimuthal anchoring energy, when the width of the unstructured gap is increased. Modifying the sapphire surface by an ITO-coating with further deposition of a polyimide film increases the azimuthal anchoring energy by a factor of about four up to Wφ ~ 4.25 × 10−6 J/m2, when the minimum width of the unstructured gap is 7 µm. Comprehensive measurements and comparisons of the azimuthal anchoring energy as well as the pretilt angle for the 1D-LSFL, unstructured gaps, and entire areas depending on the width of unstructured gaps are presented and discussed. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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13 pages, 2149 KiB  
Article
Investigation of Laser-Induced Periodic Surface Structures Using Synthetic Optical Holography
by Krisztian Neutsch, Evgeny L. Gurevich, Martin R. Hofmann and Nils C. Gerhardt
Nanomaterials 2022, 12(3), 505; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12030505 - 01 Feb 2022
Cited by 2 | Viewed by 2044
Abstract
In this paper, the investigation of laser-induced periodic surface structures (LIPSSs) on a polycrystalline diamond substrate using synthetic optical holography (SOH) is demonstrated. While many techniques for LIPSS detection operate with sample contact and/or require preparation or processing of the sample, this novel [...] Read more.
In this paper, the investigation of laser-induced periodic surface structures (LIPSSs) on a polycrystalline diamond substrate using synthetic optical holography (SOH) is demonstrated. While many techniques for LIPSS detection operate with sample contact and/or require preparation or processing of the sample, this novel technique operates entirely non-invasively without any processing of or contact with the LIPSS sample at all. The setup provides holographic amplitude and phase images of the investigated sample with confocally enhanced and diffraction-limited lateral resolution, as well as three-dimensional surface topography images of the periodic structures via phase reconstruction with one single-layer scan only. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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11 pages, 6900 KiB  
Article
Regulating Morphology and Composition of Laser-Induced Periodic Structures on Titanium Films with Femtosecond Laser Wavelength and Ambient Environment
by Kirill Bronnikov, Semyon Gladkikh, Konstantin Okotrub, Andrey Simanchuk, Alexey Zhizhchenko, Aleksandr Kuchmizhak and Alexander Dostovalov
Nanomaterials 2022, 12(3), 306; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12030306 - 18 Jan 2022
Cited by 6 | Viewed by 2036
Abstract
Recently, highly uniform thermochemical laser-induced periodic surface structures (TLIPSS) have attracted significant research attention due to their practical applicability for upscalable fabrication of periodic surface morphologies important for surface functionalization, diffraction optics, sensors, etc. When processed by femtosecond (fs) laser pulses in oxygen-containing [...] Read more.
Recently, highly uniform thermochemical laser-induced periodic surface structures (TLIPSS) have attracted significant research attention due to their practical applicability for upscalable fabrication of periodic surface morphologies important for surface functionalization, diffraction optics, sensors, etc. When processed by femtosecond (fs) laser pulses in oxygen-containing environments, TLIPSS are formed on the material surface as parallel protrusions upon local oxidation in the maxima of the periodic intensity pattern coming from interference of the incident and scattered waves. From an application point of view, it is important to control both the TLIPSS period and nanoscale morphology of the formed protrusions that can be expectedly achieved by scalable shrinkage of the laser-processing wavelength as well as by varying the ambient environment. However, so far, the fabrication of uniform TLIPSS was reported only for near-IR wavelength in air. In this work, TLIPSS formation on the surface of titanium (Ti) films was systematically studied using near-IR (1026 nm), visible (513 nm) and UV (256 nm) wavelengths revealing linear scalability of the protrusion period versus the fs-laser wavelength. By changing the ambient environment from air to vacuum (10−2 atm) and pressurized nitrogen gas (2.5 atm) we demonstrate tunability of the composition and morphology of the Ti TLIPSS protrusions. In particular, Raman spectroscopy revealed formation of TiN together with dominating TiO2 (rutile phase) in the TLIPSS protrusions produced in the nitrogen-rich atmosphere. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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19 pages, 51088 KiB  
Article
The Influence of the Processing Parameters on the Laser-Ablation of Stainless Steel and Brass during the Engraving by Nanosecond Fiber Laser
by Luka Hribar, Peter Gregorčič, Matej Senegačnik and Matija Jezeršek
Nanomaterials 2022, 12(2), 232; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12020232 - 11 Jan 2022
Cited by 19 | Viewed by 2227
Abstract
In this paper, we investigate the influence of the following parameters: pulse duration, pulse repetition rate, line-to-line and pulse-to-pulse overlaps, and scanning strategy on the ablation of AISI 316L steel and CuZn37 brass with a nanosecond, 1064-nm, Yb fiber laser. The results show [...] Read more.
In this paper, we investigate the influence of the following parameters: pulse duration, pulse repetition rate, line-to-line and pulse-to-pulse overlaps, and scanning strategy on the ablation of AISI 316L steel and CuZn37 brass with a nanosecond, 1064-nm, Yb fiber laser. The results show that the material removal rate (MRR) increases monotonically with pulse duration up to the characteristic repetition rate (f0) where pulse energy and average power are maximal. The maximum MRR is reached at a repetition rate that is equal or slightly higher as f0. The exact value depends on the correlation between the fluence of the laser pulses and the pulse repetition rate, as well as on the material properties of the sample. The results show that shielding of the laser beam by plasma and ejected material plays an important role in reducing the MRR. The surface roughness is mainly influenced by the line-to-line and the pulse-to-pulse overlaps, where larger overlap leads to lower roughness. Process optimization indicates that while operating with laser processing parameters resulting in the highest MRR, the best ratio between the MRR and surface roughness appears at ~50% overlap of the laser pulses, regardless of the material being processed. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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19 pages, 8047 KiB  
Article
Superwicking Functionality of Femtosecond Laser Textured Aluminum at High Temperatures
by Ranran Fang, Xianhang Zhang, Jiangen Zheng, Zhonglin Pan, Chen Yang, Lianrui Deng, Rui Li, Chunhong Lai, Wensheng Yan, Valeriy S. Maisotsenko and Anatoliy Y. Vorobyev
Nanomaterials 2021, 11(11), 2964; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11112964 - 04 Nov 2021
Cited by 12 | Viewed by 2305
Abstract
An advanced superwicking aluminum material based on a microgroove surface structure textured with both laser-induced periodic surface structures and fine microholes was produced by direct femtosecond laser nano/microstructuring technology. The created material demonstrates excellent wicking performance in a temperature range of 23 to [...] Read more.
An advanced superwicking aluminum material based on a microgroove surface structure textured with both laser-induced periodic surface structures and fine microholes was produced by direct femtosecond laser nano/microstructuring technology. The created material demonstrates excellent wicking performance in a temperature range of 23 to 120 °C. The experiments on wicking dynamics show a record-high velocity of water spreading that achieves about 450 mm/s at 23 °C and 320 mm/s at 120 °C when the spreading water undergoes intensive boiling. The lifetime of classic Washburn capillary flow dynamics shortens as the temperature increases up to 80 °C. The effects of evaporation and boiling on water spreading become significant above 80 °C, resulting in vanishing of Washburn’s dynamics. Both the inertial and visco-inertial flow regimes are insignificantly affected by evaporation at temperatures below the boiling point of water. The boiling effect on the inertial regime is small at 120 °C; however, its effect on the visco-inertial regime is essential. The created material with effective wicking performance under water boiling conditions can find applications in Maisotsenko cycle (M-cycle) high-temperature heat/mass exchangers for enhancing power generation efficiency that is an important factor in reducing CO2 emissions and mitigation of the global climate change. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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16 pages, 4082 KiB  
Article
In Situ Collection of Nanoparticles during Femtosecond Laser Machining in Air
by Nithin Joy and Anne-Marie Kietzig
Nanomaterials 2021, 11(9), 2264; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11092264 - 31 Aug 2021
Cited by 5 | Viewed by 2153
Abstract
Nanoparticles generated during laser material processing are often seen as annoying side products, yet they might find useful application upon proper collection. We present a parametric study to identify the dominant factors in nanoparticle removal and collection with the goal of establishing an [...] Read more.
Nanoparticles generated during laser material processing are often seen as annoying side products, yet they might find useful application upon proper collection. We present a parametric study to identify the dominant factors in nanoparticle removal and collection with the goal of establishing an in situ removal method during femtosecond laser machining. Several target materials of different electrical resistivity, such as Cu, Ti, and Si were laser machined at a relatively high laser fluence. Machining was performed under three different charge conditions, i.e., machining without an externally applied charge (alike atmospheric pulsed laser deposition (PLD)) was compared to machining with a floating potential and with an applied field. Thereby, we investigated the influence of three different charge conditions on the behavior of laser-generated nanoparticles, in particular considering plume deflection, nanoparticle accumulation on a collector plate and their redeposition onto the target. We found that both strategies, machining under a floating potential or under an applied field, were effective for collecting laser-generated nanoparticles. The applied field condition led to the strongest confinement of the nanoparticle plume and tightest resulting nanoparticle collection pattern. Raster-scanning direction was found to influence the nanoparticle collection pattern and ablation depth. However, the laser-processed target surface remained unaffected by the chosen nanoparticle collection strategy. We conclude that machining under a floating potential or an applied field is a promising setup for removing and collecting nanoparticles during the machining process, and thus provides an outlook to circular waste-free laser process design. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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Graphical abstract

9 pages, 3849 KiB  
Communication
Towards Rapid Fabrication of Superhydrophobic Surfaces by Multi-Beam Nanostructuring with 40,401 Beams
by Petr Hauschwitz, Radka Bičštová, Alexander Brodsky, Natan Kaplan, Martin Cimrman, Jaroslav Huynh, Jan Brajer, Danijela Rostohar, Jaromír Kopeček, Martin Smrž and Tomáš Mocek
Nanomaterials 2021, 11(8), 1987; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11081987 - 02 Aug 2021
Cited by 10 | Viewed by 2714
Abstract
Superhydrophobic surfaces attract a lot of attention due to many potential applications including anti-icing, anti-corrosion, self-cleaning or drag-reduction surfaces. Despite a list of attractive applications of superhydrophobic surfaces and demonstrated capability of lasers to produce them, the speed of laser micro and nanostructuring [...] Read more.
Superhydrophobic surfaces attract a lot of attention due to many potential applications including anti-icing, anti-corrosion, self-cleaning or drag-reduction surfaces. Despite a list of attractive applications of superhydrophobic surfaces and demonstrated capability of lasers to produce them, the speed of laser micro and nanostructuring is still low with respect to many industry standards. Up-to-now, most promising multi-beam solutions can improve processing speed a hundred to a thousand times. However, productive and efficient utilization of a new generation of kW-class ultrashort pulsed lasers for precise nanostructuring requires a much higher number of beams. In this work, we introduce a unique combination of high-energy pulsed ultrashort laser system delivering up to 20 mJ at 1030 nm in 1.7 ps and novel Diffractive Laser-Induced Texturing element (DLITe) capable of producing 201 × 201 sub-beams of 5 µm in diameter on a square area of 1 mm2. Simultaneous nanostructuring with 40,401 sub-beams resulted in a matrix of microcraters covered by nanogratings and ripples with periodicity below 470 nm and 720 nm, respectively. The processed area demonstrated hydrophobic to superhydrophobic properties with a maximum contact angle of 153°. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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Review

Jump to: Editorial, Research, Other

39 pages, 30620 KiB  
Review
Dynamics and Processes on Laser-Irradiated Surfaces
by Juergen Reif
Nanomaterials 2023, 13(3), 379; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13030379 - 17 Jan 2023
Cited by 2 | Viewed by 2056
Abstract
The modification of solid surfaces via the impacts of intense laser pulses and the dynamics of the relevant processes are reviewed. We start with rather weak interactions on dielectric materials, based on non-linear absorption across the bandgap and resulting in low-level local effects [...] Read more.
The modification of solid surfaces via the impacts of intense laser pulses and the dynamics of the relevant processes are reviewed. We start with rather weak interactions on dielectric materials, based on non-linear absorption across the bandgap and resulting in low-level local effects like electron and individual ion emission. The role of such locally induced defects in the cumulative effect of incubation, i.e., the increase in efficiency with the increasing number of laser pulses, is addressed. At higher excitation density levels, due to easier laser–material coupling and higher laser fluence, the energy dissipation is considerable, leading to lattice destabilization, surface relaxation, ablation, and surface modification (e.g., laser-induced periodic surface structures). Finally, a short list of possible applications, namely in the field of wettability, is presented. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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Other

21 pages, 4007 KiB  
Perspective
Ten Open Questions about Laser-Induced Periodic Surface Structures
by Jörn Bonse and Stephan Gräf
Nanomaterials 2021, 11(12), 3326; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11123326 - 07 Dec 2021
Cited by 59 | Viewed by 5402
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)
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