Ionut Balasa - Profile on Academia.edu (original) (raw)
Papers by Ionut Balasa
Data of the publication Optimizing ion implantation to create shallow NV centre ensembles in high-quality CVD diamond
Zenodo (CERN European Organization for Nuclear Research), May 31, 2023
Hot ion implantation to create dense NV center ensembles in diamond
Applied physics letters, Mar 25, 2024
Annals of DAAAM for ... & proceedings of the ... International DAAAM Symposium .., Dec 31, 2022
The present work provides a comprehensive analysis of the implementation of a washout filter in a... more The present work provides a comprehensive analysis of the implementation of a washout filter in an anthropomorphicrobotic flight simulator. It discusses the significance of adding a 7th degree of freedom (DOF) through a linear unit to enhance the pilot's perception within the flight simulator. The primary objective of this research was to develop a flight simulator on an anthropomorphic robot, serving as both a dynamic simulation system for pilot-in-the-loop applications and a pilot training platform. This simulator was designed to faithfully reproduce the sensations a pilot typically experiences during more demanding maneuvers, such as changes in G-forces in aircraft flight tests. A critical requirement for such a simulator is the accurate representation of its motion system, achieved through the proper implementation of the washout filter. This paper presents experimental results that validate the proposed solutions.
arXiv (Cornell University), Nov 8, 2023
Creating dense and shallow nitrogen-vacancy (NV) ensembles with good spin properties, is a prereq... more Creating dense and shallow nitrogen-vacancy (NV) ensembles with good spin properties, is a prerequisite for developing diamond-based quantum sensors exhibiting better performance. Ion implantation is a key enabling tool for precisely controlling spatial localisation and density of NV colour centres in diamond. However, it suffers from a low creation yield, while higher ion fluences significantly damage the crystal lattice. In this work, we realize N2 + ion implantation in the 30-40 keV range at high temperatures. At 800 °C, NV's ensemble photoluminescence emission is three to four times higher than room temperature implanted films, while narrow electron spin resonance linewidths of 1.5 MHz, comparable to well-established implantation techniques, are obtained. In addition, we found that ion fluences above 2×10 14 ions/cm² can be used without graphitization of the diamond film, in contrast to room temperature implantation. This study opens promising perspectives in optimizing diamond films with implanted NV ensembles that could be integrated into quantum sensing devices.
Optimizing ion implantation to create shallow NV centre ensembles in high-quality CVD diamond
Materials for quantum technology, Nov 14, 2022
The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the mos... more The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the most promising systems for applications in quantum technologies because of the possibility to optically manipulate and read out the spin state of this defect, even at room temperature. Nevertheless, obtaining high NV densities (>500 ppb) close to the surface (5–20 nm) while maintaining good spin properties remain challenging. In this work we rely on a versatile ion implantation system allowing both implanting nitrogen using N2 + and creating vacancies with He+ ion bombardment at variable energies and fluence to create shallow NV ensembles. By optimizing the ion irradiation conditions as well as the surface preparation prior to treatment we successfully increase the amount of created colour centres while demonstrating narrow magnetic resonance linewidths.
To Illi and my family Life does not conclude. And life knows nothing of names. This tree, tremulo... more To Illi and my family Life does not conclude. And life knows nothing of names. This tree, tremulous pulse of new leaves. I am this tree. Tree, cloud; tomorrow book or wind: the book I read, the wind I drink. All outside, wandering.
Optimizing ion implantation to create shallow NV centre ensembles in high-quality CVD diamond
Materials for Quantum Technology
The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the mos... more The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the most promising systems for applications in quantum technologies because of the possibility to optically manipulate and read out the spin state of this defect, even at room temperature. Nevertheless, obtaining high NV densities (>500 ppb) close to the surface (5–20 nm) while maintaining good spin properties remain challenging. In this work we rely on a versatile ion implantation system allowing both implanting nitrogen using N2 + and creating vacancies with He+ ion bombardment at variable energies and fluence to create shallow NV ensembles. By optimizing the ion irradiation conditions as well as the surface preparation prior to treatment we successfully increase the amount of created colour centres while demonstrating narrow magnetic resonance linewidths.
The aim of this work is the study, the design and the nanofabrication of innovative plasmonic nan... more The aim of this work is the study, the design and the nanofabrication of innovative plasmonic nanostructured materials to develop label-free optical biosensors. Noble metalbased nanostructures have gained interest in the last years due to their extraordinary optical properties, which allow to develop optical biosensors able to detect very low concentrations of specific biomolecules, called analyte, down to the picomolar range. Such biosensors rely on the Surface Plasmon Resonance (SPR) excitation which occurs under specific conditions that depend both on the morphology of the nanostructure and on the adjacent dielectric medium. Therefore, the binding of the biomolecules to metal surfaces is revealed as a change in the SPR condition. Four kinds of nanostructures are investigated in this work: ordered and disordered nanohole array (o-NHA, d-NHA), nanoprism array (NPA) and nanodisk array (NDA). The o-NHA and d-NHA consist of a thin metallic film (50 - 100 nm) patterned with, respective...
Quasi-BIC Modes in All-Dielectric Slotted Nanoantennas for Enhanced Er3+ Emission
ACS Photonics
Materials
In recent years the quest for novel materials possessing peculiar abilities of manipulating light... more In recent years the quest for novel materials possessing peculiar abilities of manipulating light at the nanoscale has been significantly boosted due to the strict demands of advanced nanophotonics and quantum technologies. In this framework radiative decay engineering of quantum emitters is of paramount importance for developing efficient single-photon sources or nanolasers. Hyperbolic metamaterials stand out among the best cutting-edge candidates for photoluminescence control owing to their potentially unlimited photonic density of states and their ability to sustain high-k modes that allow us to strongly enhance the radiative decay rate of quantum light emitters. The aim of the present paper is to show how Au/Al2O3 hyperbolic multilayers can be used to selectively control the photoluminescence of coupled Eu3+ emitters. We point out an enhancement of the Eu3+ transitions when they are in the hyperbolic regime of the metamaterials and a significant alteration of the ED and MD branc...
Physical Review Applied
Metamaterials with properly engineered linear and nonlinear optical response are of great interes... more Metamaterials with properly engineered linear and nonlinear optical response are of great interest for many advanced applications in nanophotonics and quantum optics. In the present work, we perform a detailed spectral investigation of the third-order nonlinear optical properties (nonlinear refractive index and nonlinear absorption coefficient) of-near-zero Au/Al 2 O 3 multilayer metamaterials in a broad range of the visible spectrum across their-near-zero (ENZ) wavelength, at different incidence angles with TEand TM-polarized light. Multilayers with different gold filling fractions (16 and 33%) are produced by magnetron sputtering to tune the spectral position of the-near-zero wavelength. The results demonstrate that a continuous modulation of the linear and nonlinear optical parameters of these metamaterials can be obtained as a function of the angle of incidence, with a peak of the nonlinear optical coefficients close to the ENZ wavelength. A model is proposed to describe the nonlinear optical response of the metamaterials, and an optimal agreement between experimental and simulated results is obtained in all the configurations explored. This model represents a useful tool to design multilayer metamaterials with tailored nonlinear optical properties, to be used in different experimental configurations.
Tunable optical nonlinearities in epsilon-near-zero Au/Al2O3 multilayer metamaterials
OSA Nonlinear Optics 2021, 2021
We demonstrate the angle, polarization and intensity tunability of the optical Kerr effect in gol... more We demonstrate the angle, polarization and intensity tunability of the optical Kerr effect in gold/alumina metamaterials investigated by the z-scan technique. We propose a model to predict their effective nonlinear refractive index and absorption coefficient.
Ordered arrays of metallic nanoprisms for photonic applications
The linear and nonlinear optical properties of nanostructured materials have been the object of n... more The linear and nonlinear optical properties of nanostructured materials have been the object of numerous studies due to the possibility of tailoring these properties by manipulation of their material structure; composition, particle size, and shape are some of the parameters considered for tuning the nonlinear response. The localized surface plasmon resonances encountered for metallic inclusions in dielectric media have been thoroughly investigated. Most systems consist of randomly placed nanoparticles contained in another medium. Due to the randomness of the system, the response of such a system can be seen as an incoherent addition of the individual response of each nanoparticle. By contrast, an ordered array of nanoelements in principle would allow a response that is the coherent addition of the individual element responses, and hence large effective nonlinear parameters can be expected that will also exhibit the symmetry properties of the structure. In this work, we will present...
Physical Review Applied, 2020
We study, both experimentally and theoretically, the modification of Er 3+ photoluminescence prop... more We study, both experimentally and theoretically, the modification of Er 3+ photoluminescence properties in Si dielectric nanoslots. The ultrathin nanoslot (down to 5-nm thickness), filled with Er in SiO 2 , boosts the electric and magnetic local density of states via coherent near-field interaction. We report an experimental 20-fold enhancement of the radiative decay rate with negligible losses. Moreover, via modifying the geometry of the all-dielectric nanoslot, the outcoupling of the emitted radiation to the far field can be strongly improved, without affecting the strong decay-rate enhancement given by the nanoslot structure. Indeed, for a periodic square array of slotted nanopillars an almost one-order-of-magnitude-higher Er 3+ PL intensity is measured with respect to the unpatterned structures. This has a direct impact on the design of more efficient CMOS-compatible light sources operating at telecom wavelengths.
Double-Langmuir model for optimized nanohole array-based plasmonic biosensors
Applied Surface Science, 2021
Abstract The sensing mechanism of plasmonic nanohole arrays is investigated and a novel model is ... more Abstract The sensing mechanism of plasmonic nanohole arrays is investigated and a novel model is proposed to interpret their optical response over a wide dynamic range of concentrations ( 10 - 13 - 10 - 5 M), based on a double-Langmuir model. This model describes the signal response of the analyte binding as the sum of two independent contributions which are related to two different surface regions of the biosensor, namely the top gold surface of the nanohole array and the lateral gold area inside the nanoholes. Numerical simulations highlight the different near-field behaviour of these two regions and their very different refractive index sensitivities, which both support the double-Langmuir model. This is corroborated by experimental biosensing measurements with gold nanohole arrays with hexagonal symmetry, synthesized by nanosphere lithography. Their sensing performances are optimized by numerical simulations by changing their geometrical parameters (i.e., lattice constant, nanohole diameter and height) in order to achieve a maximum sensitivity. For the biosensing experiments, the biotin-streptavidin complex is used as a benchmark test for the optimized nanohole array and a robust calibration is provided by the double-Langmuir model obtaining a limit of detection of 0.3 ng/mL, which corresponds to an absolute analyte quantity of 0.02 fmol.
Nanoscale Advances, 2020
Non-interacting, disordered plasmonic nanodisk arrays have competitive performances for local and... more Non-interacting, disordered plasmonic nanodisk arrays have competitive performances for local and bulk sensing and a large stability basin around the maximum sensitivities.
Structural modification of Au-Co thin films induced by annealing in oxidizing atmosphere
Surface and Coatings Technology, 2020
Abstract The stability upon air-annealing of uncapped Au-Co thin films is investigated. The analy... more Abstract The stability upon air-annealing of uncapped Au-Co thin films is investigated. The analysis focuses on the modifications of the crystalline fraction of the films produced by physical vapor deposition. The film with the highest Au concentration exhibits the strongest diffraction signal, corresponding to a Au-rich fcc AuxCo1−x solid solution alloy, with nanocrystals which have a rod-like shape. Air annealing induces a progressive de-alloying which is complete at 500 °C, as shown by X-ray Absorption Spectroscopy and X-ray diffraction. The film, that is directly exposed to the oxidizing atmosphere, undergoes a de-wetting process, likely triggered by Au. X-ray nanoimaging mapping enlightens the presence of interpenetrating sub-μm Au and Co3O4 domains. This peculiar annealed nanostructured system can have interesting applications in the field of catalysis.
Applied Surface Science, 2019
We evaluate the performance of an adhesion buffer layer between ordered metal nanoparticle arrays... more We evaluate the performance of an adhesion buffer layer between ordered metal nanoparticle arrays and dielectric substrates on the particles' morphological manipulation by pulsed laser irradiation. The experiments are performed irradiating with only one nanosecond pulse at 355 nm, triangular nanoprism arrays fabricated by nanosphere lithography (polystyrene spheres with 1030 nm in diameter), followed by film deposition by magnetron sputtering. The reshaping of the nanoprisms into spheres as result of laser-induced melting is investigated for three different materials: prisms made of Cr, Au and Au with a buffer layer made of Cr (Au/Cr). These elements are chosen because their interfacial interaction with the substrates (soda-lime glass and fused silica) is quite different. Our results show that single pulse irradiation at fluences above the metal melting threshold allows the formation of disorder spheres for the case of Au, but ordered spheres for the cases of Cr and Cr/Au. Therefore, the function of the buffer layer is to improve the adhesion between the prisms and the substrate, thus allowing their reshaping by laser-induced melting but preserving their position. The strong interaction between Cr and the substrate is also exploited for the nanostructuration of the substrate by the formation of ordered holes with submicrometer dimensions. These findings reboot laser postprocessing of ordered structures fabricated by nanosphere lithography exploit to explore new capacities of nanostructuration.
Data of the publication Optimizing ion implantation to create shallow NV centre ensembles in high-quality CVD diamond
Zenodo (CERN European Organization for Nuclear Research), May 31, 2023
Hot ion implantation to create dense NV center ensembles in diamond
Applied physics letters, Mar 25, 2024
Annals of DAAAM for ... & proceedings of the ... International DAAAM Symposium .., Dec 31, 2022
The present work provides a comprehensive analysis of the implementation of a washout filter in a... more The present work provides a comprehensive analysis of the implementation of a washout filter in an anthropomorphicrobotic flight simulator. It discusses the significance of adding a 7th degree of freedom (DOF) through a linear unit to enhance the pilot's perception within the flight simulator. The primary objective of this research was to develop a flight simulator on an anthropomorphic robot, serving as both a dynamic simulation system for pilot-in-the-loop applications and a pilot training platform. This simulator was designed to faithfully reproduce the sensations a pilot typically experiences during more demanding maneuvers, such as changes in G-forces in aircraft flight tests. A critical requirement for such a simulator is the accurate representation of its motion system, achieved through the proper implementation of the washout filter. This paper presents experimental results that validate the proposed solutions.
arXiv (Cornell University), Nov 8, 2023
Creating dense and shallow nitrogen-vacancy (NV) ensembles with good spin properties, is a prereq... more Creating dense and shallow nitrogen-vacancy (NV) ensembles with good spin properties, is a prerequisite for developing diamond-based quantum sensors exhibiting better performance. Ion implantation is a key enabling tool for precisely controlling spatial localisation and density of NV colour centres in diamond. However, it suffers from a low creation yield, while higher ion fluences significantly damage the crystal lattice. In this work, we realize N2 + ion implantation in the 30-40 keV range at high temperatures. At 800 °C, NV's ensemble photoluminescence emission is three to four times higher than room temperature implanted films, while narrow electron spin resonance linewidths of 1.5 MHz, comparable to well-established implantation techniques, are obtained. In addition, we found that ion fluences above 2×10 14 ions/cm² can be used without graphitization of the diamond film, in contrast to room temperature implantation. This study opens promising perspectives in optimizing diamond films with implanted NV ensembles that could be integrated into quantum sensing devices.
Optimizing ion implantation to create shallow NV centre ensembles in high-quality CVD diamond
Materials for quantum technology, Nov 14, 2022
The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the mos... more The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the most promising systems for applications in quantum technologies because of the possibility to optically manipulate and read out the spin state of this defect, even at room temperature. Nevertheless, obtaining high NV densities (>500 ppb) close to the surface (5–20 nm) while maintaining good spin properties remain challenging. In this work we rely on a versatile ion implantation system allowing both implanting nitrogen using N2 + and creating vacancies with He+ ion bombardment at variable energies and fluence to create shallow NV ensembles. By optimizing the ion irradiation conditions as well as the surface preparation prior to treatment we successfully increase the amount of created colour centres while demonstrating narrow magnetic resonance linewidths.
To Illi and my family Life does not conclude. And life knows nothing of names. This tree, tremulo... more To Illi and my family Life does not conclude. And life knows nothing of names. This tree, tremulous pulse of new leaves. I am this tree. Tree, cloud; tomorrow book or wind: the book I read, the wind I drink. All outside, wandering.
Optimizing ion implantation to create shallow NV centre ensembles in high-quality CVD diamond
Materials for Quantum Technology
The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the mos... more The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the most promising systems for applications in quantum technologies because of the possibility to optically manipulate and read out the spin state of this defect, even at room temperature. Nevertheless, obtaining high NV densities (>500 ppb) close to the surface (5–20 nm) while maintaining good spin properties remain challenging. In this work we rely on a versatile ion implantation system allowing both implanting nitrogen using N2 + and creating vacancies with He+ ion bombardment at variable energies and fluence to create shallow NV ensembles. By optimizing the ion irradiation conditions as well as the surface preparation prior to treatment we successfully increase the amount of created colour centres while demonstrating narrow magnetic resonance linewidths.
The aim of this work is the study, the design and the nanofabrication of innovative plasmonic nan... more The aim of this work is the study, the design and the nanofabrication of innovative plasmonic nanostructured materials to develop label-free optical biosensors. Noble metalbased nanostructures have gained interest in the last years due to their extraordinary optical properties, which allow to develop optical biosensors able to detect very low concentrations of specific biomolecules, called analyte, down to the picomolar range. Such biosensors rely on the Surface Plasmon Resonance (SPR) excitation which occurs under specific conditions that depend both on the morphology of the nanostructure and on the adjacent dielectric medium. Therefore, the binding of the biomolecules to metal surfaces is revealed as a change in the SPR condition. Four kinds of nanostructures are investigated in this work: ordered and disordered nanohole array (o-NHA, d-NHA), nanoprism array (NPA) and nanodisk array (NDA). The o-NHA and d-NHA consist of a thin metallic film (50 - 100 nm) patterned with, respective...
Quasi-BIC Modes in All-Dielectric Slotted Nanoantennas for Enhanced Er3+ Emission
ACS Photonics
Materials
In recent years the quest for novel materials possessing peculiar abilities of manipulating light... more In recent years the quest for novel materials possessing peculiar abilities of manipulating light at the nanoscale has been significantly boosted due to the strict demands of advanced nanophotonics and quantum technologies. In this framework radiative decay engineering of quantum emitters is of paramount importance for developing efficient single-photon sources or nanolasers. Hyperbolic metamaterials stand out among the best cutting-edge candidates for photoluminescence control owing to their potentially unlimited photonic density of states and their ability to sustain high-k modes that allow us to strongly enhance the radiative decay rate of quantum light emitters. The aim of the present paper is to show how Au/Al2O3 hyperbolic multilayers can be used to selectively control the photoluminescence of coupled Eu3+ emitters. We point out an enhancement of the Eu3+ transitions when they are in the hyperbolic regime of the metamaterials and a significant alteration of the ED and MD branc...
Physical Review Applied
Metamaterials with properly engineered linear and nonlinear optical response are of great interes... more Metamaterials with properly engineered linear and nonlinear optical response are of great interest for many advanced applications in nanophotonics and quantum optics. In the present work, we perform a detailed spectral investigation of the third-order nonlinear optical properties (nonlinear refractive index and nonlinear absorption coefficient) of-near-zero Au/Al 2 O 3 multilayer metamaterials in a broad range of the visible spectrum across their-near-zero (ENZ) wavelength, at different incidence angles with TEand TM-polarized light. Multilayers with different gold filling fractions (16 and 33%) are produced by magnetron sputtering to tune the spectral position of the-near-zero wavelength. The results demonstrate that a continuous modulation of the linear and nonlinear optical parameters of these metamaterials can be obtained as a function of the angle of incidence, with a peak of the nonlinear optical coefficients close to the ENZ wavelength. A model is proposed to describe the nonlinear optical response of the metamaterials, and an optimal agreement between experimental and simulated results is obtained in all the configurations explored. This model represents a useful tool to design multilayer metamaterials with tailored nonlinear optical properties, to be used in different experimental configurations.
Tunable optical nonlinearities in epsilon-near-zero Au/Al2O3 multilayer metamaterials
OSA Nonlinear Optics 2021, 2021
We demonstrate the angle, polarization and intensity tunability of the optical Kerr effect in gol... more We demonstrate the angle, polarization and intensity tunability of the optical Kerr effect in gold/alumina metamaterials investigated by the z-scan technique. We propose a model to predict their effective nonlinear refractive index and absorption coefficient.
Ordered arrays of metallic nanoprisms for photonic applications
The linear and nonlinear optical properties of nanostructured materials have been the object of n... more The linear and nonlinear optical properties of nanostructured materials have been the object of numerous studies due to the possibility of tailoring these properties by manipulation of their material structure; composition, particle size, and shape are some of the parameters considered for tuning the nonlinear response. The localized surface plasmon resonances encountered for metallic inclusions in dielectric media have been thoroughly investigated. Most systems consist of randomly placed nanoparticles contained in another medium. Due to the randomness of the system, the response of such a system can be seen as an incoherent addition of the individual response of each nanoparticle. By contrast, an ordered array of nanoelements in principle would allow a response that is the coherent addition of the individual element responses, and hence large effective nonlinear parameters can be expected that will also exhibit the symmetry properties of the structure. In this work, we will present...
Physical Review Applied, 2020
We study, both experimentally and theoretically, the modification of Er 3+ photoluminescence prop... more We study, both experimentally and theoretically, the modification of Er 3+ photoluminescence properties in Si dielectric nanoslots. The ultrathin nanoslot (down to 5-nm thickness), filled with Er in SiO 2 , boosts the electric and magnetic local density of states via coherent near-field interaction. We report an experimental 20-fold enhancement of the radiative decay rate with negligible losses. Moreover, via modifying the geometry of the all-dielectric nanoslot, the outcoupling of the emitted radiation to the far field can be strongly improved, without affecting the strong decay-rate enhancement given by the nanoslot structure. Indeed, for a periodic square array of slotted nanopillars an almost one-order-of-magnitude-higher Er 3+ PL intensity is measured with respect to the unpatterned structures. This has a direct impact on the design of more efficient CMOS-compatible light sources operating at telecom wavelengths.
Double-Langmuir model for optimized nanohole array-based plasmonic biosensors
Applied Surface Science, 2021
Abstract The sensing mechanism of plasmonic nanohole arrays is investigated and a novel model is ... more Abstract The sensing mechanism of plasmonic nanohole arrays is investigated and a novel model is proposed to interpret their optical response over a wide dynamic range of concentrations ( 10 - 13 - 10 - 5 M), based on a double-Langmuir model. This model describes the signal response of the analyte binding as the sum of two independent contributions which are related to two different surface regions of the biosensor, namely the top gold surface of the nanohole array and the lateral gold area inside the nanoholes. Numerical simulations highlight the different near-field behaviour of these two regions and their very different refractive index sensitivities, which both support the double-Langmuir model. This is corroborated by experimental biosensing measurements with gold nanohole arrays with hexagonal symmetry, synthesized by nanosphere lithography. Their sensing performances are optimized by numerical simulations by changing their geometrical parameters (i.e., lattice constant, nanohole diameter and height) in order to achieve a maximum sensitivity. For the biosensing experiments, the biotin-streptavidin complex is used as a benchmark test for the optimized nanohole array and a robust calibration is provided by the double-Langmuir model obtaining a limit of detection of 0.3 ng/mL, which corresponds to an absolute analyte quantity of 0.02 fmol.
Nanoscale Advances, 2020
Non-interacting, disordered plasmonic nanodisk arrays have competitive performances for local and... more Non-interacting, disordered plasmonic nanodisk arrays have competitive performances for local and bulk sensing and a large stability basin around the maximum sensitivities.
Structural modification of Au-Co thin films induced by annealing in oxidizing atmosphere
Surface and Coatings Technology, 2020
Abstract The stability upon air-annealing of uncapped Au-Co thin films is investigated. The analy... more Abstract The stability upon air-annealing of uncapped Au-Co thin films is investigated. The analysis focuses on the modifications of the crystalline fraction of the films produced by physical vapor deposition. The film with the highest Au concentration exhibits the strongest diffraction signal, corresponding to a Au-rich fcc AuxCo1−x solid solution alloy, with nanocrystals which have a rod-like shape. Air annealing induces a progressive de-alloying which is complete at 500 °C, as shown by X-ray Absorption Spectroscopy and X-ray diffraction. The film, that is directly exposed to the oxidizing atmosphere, undergoes a de-wetting process, likely triggered by Au. X-ray nanoimaging mapping enlightens the presence of interpenetrating sub-μm Au and Co3O4 domains. This peculiar annealed nanostructured system can have interesting applications in the field of catalysis.
Applied Surface Science, 2019
We evaluate the performance of an adhesion buffer layer between ordered metal nanoparticle arrays... more We evaluate the performance of an adhesion buffer layer between ordered metal nanoparticle arrays and dielectric substrates on the particles' morphological manipulation by pulsed laser irradiation. The experiments are performed irradiating with only one nanosecond pulse at 355 nm, triangular nanoprism arrays fabricated by nanosphere lithography (polystyrene spheres with 1030 nm in diameter), followed by film deposition by magnetron sputtering. The reshaping of the nanoprisms into spheres as result of laser-induced melting is investigated for three different materials: prisms made of Cr, Au and Au with a buffer layer made of Cr (Au/Cr). These elements are chosen because their interfacial interaction with the substrates (soda-lime glass and fused silica) is quite different. Our results show that single pulse irradiation at fluences above the metal melting threshold allows the formation of disorder spheres for the case of Au, but ordered spheres for the cases of Cr and Cr/Au. Therefore, the function of the buffer layer is to improve the adhesion between the prisms and the substrate, thus allowing their reshaping by laser-induced melting but preserving their position. The strong interaction between Cr and the substrate is also exploited for the nanostructuration of the substrate by the formation of ordered holes with submicrometer dimensions. These findings reboot laser postprocessing of ordered structures fabricated by nanosphere lithography exploit to explore new capacities of nanostructuration.