We introduce a novel method to create mid-infrared(MIR)thermal emitters using fully epitaxial,metal-free structures.Through the strategic use of epsilon-near-zero(ENZ)thin films in InAs layers,we achieve a narrow-band...We introduce a novel method to create mid-infrared(MIR)thermal emitters using fully epitaxial,metal-free structures.Through the strategic use of epsilon-near-zero(ENZ)thin films in InAs layers,we achieve a narrow-band,wide-angle,and p-polarized thermal emission spectra.This approach,employing molecular beam epitaxy,circumvents the complexities associated with current layered structures and yields temperature-resistant emission wavelengths.Our findings contribute a promising route towards simpler,more efficient MIR optoelectronic devices.展开更多
The photovoltaic(PV)market is currently dominated by silicon based solar cells.However technological diversification is essential to promote competition,which is the driving force for technological growth.Historically...The photovoltaic(PV)market is currently dominated by silicon based solar cells.However technological diversification is essential to promote competition,which is the driving force for technological growth.Historically,the choice of PV materials has been limited to the three-dimensional(3D)compounds with a high crystal symmetry and direct band gap.However,to meet the strict demands for sustainable PV applications,material space has been expanded beyond 3D compounds.In this perspective we discuss the potential of low-dimensional materials(2D,1D)for application in PVs.We present unique features of low-dimensional materials in context of their suitability in the solar cells.The band gap,absorption,carrier dynamics,mobility,defects,surface states and growth kinetics are discussed and compared to 3D counterparts,providing a comprehensive view of prospects of low-dimensional materials.Structural dimensionality leads to a highly anisotropic carrier transport,complex defect chemistry and peculiar growth dynamics.By providing fundamental insights into these challenges we aim to deepen the understanding of low-dimensional materials and expand the scope of their application.Finally,we discuss the current research status and development trend of solar cell devices made of low-dimensional materials.展开更多
The growth of the microscopic fungi on the solid surface has a great influence on technical materials destruction. The aim of this study was to determine the influence of two strains of micromycetesPenicillium palitan...The growth of the microscopic fungi on the solid surface has a great influence on technical materials destruction. The aim of this study was to determine the influence of two strains of micromycetesPenicillium palitansstrain6 andArthrinium phaeospermumstrain 10 on morphological and structural properties of carbon steel surfaces in the nutrient medium. The difference in consumption of chlorine byP. palitans6(0.07 wt%) andA. phaeospermum10(0.04 wt%) and the difference in accumulation of a newly formed elementmanganese forP. palitans6(0.01 wt%) andA. phaeospermum10(0.03 wt%) has been observed. A relation between the surface and interface fungal stimulated processes, the biotic oxidation of steel surface as well as formation of the mixed oxides on the biomodified steel surface has been determined. The morphology of surfaces was characterized by scanning electron microscopy, the structure—by the X-ray diffraction method, Fourier transformation infrared and X-ray fluorescence spectroscopy.展开更多
The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials wit...The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.展开更多
Surface morphology and deuterium retention in ultrafine-grained tungsten fabricated by equal-channel angular pressing(ECAP) have been examined after exposure to a low energy,high-flux deuterium(D) plasma at fluences o...Surface morphology and deuterium retention in ultrafine-grained tungsten fabricated by equal-channel angular pressing(ECAP) have been examined after exposure to a low energy,high-flux deuterium(D) plasma at fluences of 3×10^(24) D/m^2 and 1×10^(25) D/m^2 in a temperature range of 100 ℃-150 ℃.The methods used were scanning electron microscopy(SEM) and thermal desorption spectroscopy(TDS).Sparse and small blisters(~0.1 μm) were observed by SEM after D plasma irradiation on every irradiated surface;yet they did not exhibit significant structure or plasma fluence dependence.Larger blisters or protrusions appeared after subsequent TDS heating up to 1000 ℃.The TDS results showed a single D desorption peak at ~220℃ for all samples and the D retention increased with increasing numbers of extrusion passes,i.e.,the decrease of grain sizes.The increased D retention in this low temperature range should be attributed to the faster diffusion of D along the larger volume fraction of grain boundaries introduced by ECAP.展开更多
A solution containing Cr(VI), Cr(NO3)3 and its complex with an organic acid as well as several commercial solutions containing Cr(III) complexes with an organic acid and additionally CO2+, F-, SO42- ions were used for...A solution containing Cr(VI), Cr(NO3)3 and its complex with an organic acid as well as several commercial solutions containing Cr(III) complexes with an organic acid and additionally CO2+, F-, SO42- ions were used for the studies. Results of the studies obtained in the following commercial solutions: Likonda 2AT, Cr(NO3)3 + malonic acid;Likonda 3Cr5 and Likonda 3CrMC are discussed. Steel coated with chromated Zn coatings was contaminated by some microscopic fungi. The variety of fungi on chromated plates diminished, however the propagules of fungi did not disappear completely. The Likonda 3Cr5 solution diminishes fungi contamination on chromated steel most effectively. In water used to rinse the surface of chromated plates the number of fungi propagules was detected to be higher as compared to that on the plate surface. The least quantity of fungi propagules was detected in water used to rinse plates coated in the Likonda 3Cr5 solution. The main part of fungi detected on chromated plates treated in the Likonda 3Cr5 solution were the fungi of Cladosporium species (C.herbarum, C.cladosporioides). The latter species also dominated on chromated plates coated with zinc and treated with the other solution. It should be mentioned, that on these plates chromated in this solution, Actinomycetes of the Streptomyces group were abundant. After comparison of surfaces of the plates treated in four solutions it has been determined that the surface of the plates treated in the Likonda 3Cr5 passivation solution and exposed to modelling conditions changed least of all. It has been noticed that on the subject studied white porous rust accumulates, the intensity of this process on the surface studied determines both the probability of corrosion and the resistance of the used safety means to the external factors.展开更多
Cadmium selenide(CdSe)belongs to the binary II-VI group semiconductor with a direct bandgap of~1.7 eV.The suitable bandgap,high stability,and low manufacturing cost make CdSe an extraordinary candidate as the top cell...Cadmium selenide(CdSe)belongs to the binary II-VI group semiconductor with a direct bandgap of~1.7 eV.The suitable bandgap,high stability,and low manufacturing cost make CdSe an extraordinary candidate as the top cell material in silicon-based tandem solar cells.However,only a few studies have focused on CdSe thin-film solar cells in the past decades.With the advantages of a high deposition rate(~2µm/min)and high uniformity,rapid thermal evaporation(RTE)was used to maximize the use efficiency of CdSe source material.A stable and pure hexagonal phase CdSe thin film with a large grain size was achieved.The CdSe film demonstrated a 1.72 eV bandgap,narrow photoluminescence peak,and fast photoresponse.With the optimal device structure and film thickness,we finally achieved a preliminary efficiency of 1.88%for CdSe thin-film solar cells,suggesting the applicability of CdSe thin-film solar cells.展开更多
Background:The growing public health concern caused by non-communicable diseases in urban surroundings cannot be solved by health care alone;therefore a multidisciplinary approach is mandatory.This study aimed to eval...Background:The growing public health concern caused by non-communicable diseases in urban surroundings cannot be solved by health care alone;therefore a multidisciplinary approach is mandatory.This study aimed to evaluate the airborne aerosol pollution level in primary schools as possible factor influencing origin and course of the diseases in children.Methods:Seasonal aerosol particle number concentration(PNC)and mass concentration(PMC)were studied in the randomly selected eleven primary schools in the Lithuanian capital,Vilnius,as model of a middle-size Eastern European city.Total PNC in the size range from 0.01 to>1.0μm in diameter was measured using a condensation particle counter.Using an optical particle sizer,PNC was measured and PMC estimated for particles from 0.3 to 10.0μm.A descriptive statistics was used to estimate the aerosol pollution levels.Results:During all seasons,local cafeterias in the absence of ventilation were the main sources of the elevated levels of indoor PMC and PNC(up to 97,500 particles/cm3).The other sources of airborne particulates were the children’s activity during the lesson breaks with PMC up to 586μg/m3.Soft furniture,carpets in the classrooms and corridors were responsible for PMC up to 200μg/m3.Outdoor aerosol pollution(up to 18,170 particles/cm3)was higher for schools in city center.Elevated air pollution in classrooms also resulted from intermittent sources,such as construction work during classes(200-1000μg/m3)and petrol-powered lawn trimmers(up to 66,400 particles/cm3).Conclusion:The results of our survey show that even in a relatively low polluted region of Eastern Europe there are big differences in aerosol pollution within middle-sized city.Additional efforts are needed to improve air quality in schools:more frequent wet cleaning,monitoring the operation of ventilation systems,a ban on construction works during school year,on a use of sandblasting mechanisms in the neighborhood of schools.展开更多
We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15μm.An affordable two-stage ytterbium-doped yttrium aluminum garnet(Yb:YAG)chirped pulse ...We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15μm.An affordable two-stage ytterbium-doped yttrium aluminum garnet(Yb:YAG)chirped pulse amplifier provides more than 10 mJ,approximately 1.2 ps pulses at 1030 nm to pump a three-stage optical parametric chirped pulse amplifier(OPCPA)based on bismuth borate crystals and to drive the supercontinuum seed in the YAG crystal.The energy of the amplified pulses in the wavelength range of 1.95–2.4μm reached 2.25 mJ with a pump-tosignal conversion efficiency of approximately 25%in the last OPCPA stage.These pulses were compressed to 38 fs in a pair of Suprasil 300 glass prisms.展开更多
Controlling the spatial distribution of functional groups on two-dimensional(2D)materials on a micrometer scale and below represents a fascinating opportunity to achieve anisotropic(opto)electronic properties of these...Controlling the spatial distribution of functional groups on two-dimensional(2D)materials on a micrometer scale and below represents a fascinating opportunity to achieve anisotropic(opto)electronic properties of these materials.Periodic patterns of covalent functionalization can lead to pericxJic potentials in the monolayer;however,creating such superstructures is very challenging.Here,we describe an original approach to the periodic functionalization of graphene induced by substrate patterning using a pulsed laser.Laser-induced periodic surface structures(LIPSS)are produced on silicon wafers with thermally-grown oxide layers.The irradiation conditions for the formation of UPSS confined at the SiO2/Si interface have been unravelled.LIPSS imprint their periodicity to the reactivity of the monolayer graphene placed on the substrate via modulation of its local doping level.This method is clean,straightforward and scalable with high spatial resolution.展开更多
Structured light–electromagnetic waves with a strong spatial inhomogeneity of amplitude,phase,and polarization–has occupied far-reaching positions in both optical research and applications.Terahertz(THz)waves,due to...Structured light–electromagnetic waves with a strong spatial inhomogeneity of amplitude,phase,and polarization–has occupied far-reaching positions in both optical research and applications.Terahertz(THz)waves,due to recent innovations in photonics and nanotechnology,became so robust that it was not only implemented in a wide variety of applications such as communications,spectroscopic analysis,and non-destructive imaging,but also served as a low-cost and easily implementable experimental platform for novel concept illustration.In this work,we show that structured nonparaxial THz light in the form of Airy,Bessel,and Gaussian beams can be generated in a compact way using exclusively silicon diffractive optics prepared by femtosecond laser ablation technology.The accelerating nature of the generated structured light is demonstrated via THz imaging of objects partially obscured by an opaque beam block.Unlike conventional paraxial approaches,when a combination of a lens and a cubic phase(or amplitude)mask creates a nondiffracting Airy beam,we demonstrate simultaneous lensless nonparaxial THz Airy beam generation and its application in imaging system.Images of single objects,imaging with a controllable placed obstacle,and imaging of stacked graphene layers are presented,revealing hence potential of the approach to inspect quality of 2D materials.Structured nonparaxial THz illumination is investigated both theoretically and experimentally with appropriate extensive benchmarks.The structured THz illumination consistently outperforms the conventional one in resolution and contrast,thus opening new frontiers of structured light applications in imaging and inverse scattering problems,as it enables sophisticated estimates of optical properties of the investigated structures.展开更多
文摘We introduce a novel method to create mid-infrared(MIR)thermal emitters using fully epitaxial,metal-free structures.Through the strategic use of epsilon-near-zero(ENZ)thin films in InAs layers,we achieve a narrow-band,wide-angle,and p-polarized thermal emission spectra.This approach,employing molecular beam epitaxy,circumvents the complexities associated with current layered structures and yields temperature-resistant emission wavelengths.Our findings contribute a promising route towards simpler,more efficient MIR optoelectronic devices.
基金supported by the National Natural Science Foundation of China(61725401,61904058,61904058)the National Key R&D Program of China(2016YFA0204000)+1 种基金China Postdoctoral Science Foundation Project(2019M662623)the National Postdoctoral Program for Innovative Talent(BX20190127).
文摘The photovoltaic(PV)market is currently dominated by silicon based solar cells.However technological diversification is essential to promote competition,which is the driving force for technological growth.Historically,the choice of PV materials has been limited to the three-dimensional(3D)compounds with a high crystal symmetry and direct band gap.However,to meet the strict demands for sustainable PV applications,material space has been expanded beyond 3D compounds.In this perspective we discuss the potential of low-dimensional materials(2D,1D)for application in PVs.We present unique features of low-dimensional materials in context of their suitability in the solar cells.The band gap,absorption,carrier dynamics,mobility,defects,surface states and growth kinetics are discussed and compared to 3D counterparts,providing a comprehensive view of prospects of low-dimensional materials.Structural dimensionality leads to a highly anisotropic carrier transport,complex defect chemistry and peculiar growth dynamics.By providing fundamental insights into these challenges we aim to deepen the understanding of low-dimensional materials and expand the scope of their application.Finally,we discuss the current research status and development trend of solar cell devices made of low-dimensional materials.
文摘The growth of the microscopic fungi on the solid surface has a great influence on technical materials destruction. The aim of this study was to determine the influence of two strains of micromycetesPenicillium palitansstrain6 andArthrinium phaeospermumstrain 10 on morphological and structural properties of carbon steel surfaces in the nutrient medium. The difference in consumption of chlorine byP. palitans6(0.07 wt%) andA. phaeospermum10(0.04 wt%) and the difference in accumulation of a newly formed elementmanganese forP. palitans6(0.01 wt%) andA. phaeospermum10(0.03 wt%) has been observed. A relation between the surface and interface fungal stimulated processes, the biotic oxidation of steel surface as well as formation of the mixed oxides on the biomodified steel surface has been determined. The morphology of surfaces was characterized by scanning electron microscopy, the structure—by the X-ray diffraction method, Fourier transformation infrared and X-ray fluorescence spectroscopy.
基金The US AMRDEC grant No.W911NF-16-2-0069“Enhanced Absorption in Stopped-Light Photonic Nanostructures:Applications to Efficient Sensing”EU LASERLAB-EUROPE(grant agreement No.871124Horizon 2020 research and innovation programme)projects are acknowleged for the financial support.D.G.acknowledges the financial support from the European Social Fund(project No 09.3.3-LMT-K712-17-0016)under grant agreement with the Research Council of Lithuania(LMTLT).
文摘The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB105001,2013GB105002,2015GB109001)National Natural Science Foundation of China(Nos.11305213,11405201)+1 种基金Technological Development Grant of Hefei Science Center of CAS(No.2014TDG-HSC003)China National Funds for Distinguished Young Scientists(No.51325103)
文摘Surface morphology and deuterium retention in ultrafine-grained tungsten fabricated by equal-channel angular pressing(ECAP) have been examined after exposure to a low energy,high-flux deuterium(D) plasma at fluences of 3×10^(24) D/m^2 and 1×10^(25) D/m^2 in a temperature range of 100 ℃-150 ℃.The methods used were scanning electron microscopy(SEM) and thermal desorption spectroscopy(TDS).Sparse and small blisters(~0.1 μm) were observed by SEM after D plasma irradiation on every irradiated surface;yet they did not exhibit significant structure or plasma fluence dependence.Larger blisters or protrusions appeared after subsequent TDS heating up to 1000 ℃.The TDS results showed a single D desorption peak at ~220℃ for all samples and the D retention increased with increasing numbers of extrusion passes,i.e.,the decrease of grain sizes.The increased D retention in this low temperature range should be attributed to the faster diffusion of D along the larger volume fraction of grain boundaries introduced by ECAP.
文摘A solution containing Cr(VI), Cr(NO3)3 and its complex with an organic acid as well as several commercial solutions containing Cr(III) complexes with an organic acid and additionally CO2+, F-, SO42- ions were used for the studies. Results of the studies obtained in the following commercial solutions: Likonda 2AT, Cr(NO3)3 + malonic acid;Likonda 3Cr5 and Likonda 3CrMC are discussed. Steel coated with chromated Zn coatings was contaminated by some microscopic fungi. The variety of fungi on chromated plates diminished, however the propagules of fungi did not disappear completely. The Likonda 3Cr5 solution diminishes fungi contamination on chromated steel most effectively. In water used to rinse the surface of chromated plates the number of fungi propagules was detected to be higher as compared to that on the plate surface. The least quantity of fungi propagules was detected in water used to rinse plates coated in the Likonda 3Cr5 solution. The main part of fungi detected on chromated plates treated in the Likonda 3Cr5 solution were the fungi of Cladosporium species (C.herbarum, C.cladosporioides). The latter species also dominated on chromated plates coated with zinc and treated with the other solution. It should be mentioned, that on these plates chromated in this solution, Actinomycetes of the Streptomyces group were abundant. After comparison of surfaces of the plates treated in four solutions it has been determined that the surface of the plates treated in the Likonda 3Cr5 passivation solution and exposed to modelling conditions changed least of all. It has been noticed that on the subject studied white porous rust accumulates, the intensity of this process on the surface studied determines both the probability of corrosion and the resistance of the used safety means to the external factors.
基金the National NaturalScience Foundation of China (Grant Nos. 61725401, 61904058,and 62050039)the National Key R&D Program of China (No.2016YFA0204000)+2 种基金the Innovation Fund of WNLO, National PostdoctoralProgram for Innovative Talent (No. BX20190127)the Graduates’ InnovationFund of Huazhong University of Science and Technology (No.2020yjsCXCY003)China Postdoctoral Science Foundation Project(Nos. 2019M662623 and 2020M680101).
文摘Cadmium selenide(CdSe)belongs to the binary II-VI group semiconductor with a direct bandgap of~1.7 eV.The suitable bandgap,high stability,and low manufacturing cost make CdSe an extraordinary candidate as the top cell material in silicon-based tandem solar cells.However,only a few studies have focused on CdSe thin-film solar cells in the past decades.With the advantages of a high deposition rate(~2µm/min)and high uniformity,rapid thermal evaporation(RTE)was used to maximize the use efficiency of CdSe source material.A stable and pure hexagonal phase CdSe thin film with a large grain size was achieved.The CdSe film demonstrated a 1.72 eV bandgap,narrow photoluminescence peak,and fast photoresponse.With the optimal device structure and film thickness,we finally achieved a preliminary efficiency of 1.88%for CdSe thin-film solar cells,suggesting the applicability of CdSe thin-film solar cells.
文摘Background:The growing public health concern caused by non-communicable diseases in urban surroundings cannot be solved by health care alone;therefore a multidisciplinary approach is mandatory.This study aimed to evaluate the airborne aerosol pollution level in primary schools as possible factor influencing origin and course of the diseases in children.Methods:Seasonal aerosol particle number concentration(PNC)and mass concentration(PMC)were studied in the randomly selected eleven primary schools in the Lithuanian capital,Vilnius,as model of a middle-size Eastern European city.Total PNC in the size range from 0.01 to>1.0μm in diameter was measured using a condensation particle counter.Using an optical particle sizer,PNC was measured and PMC estimated for particles from 0.3 to 10.0μm.A descriptive statistics was used to estimate the aerosol pollution levels.Results:During all seasons,local cafeterias in the absence of ventilation were the main sources of the elevated levels of indoor PMC and PNC(up to 97,500 particles/cm3).The other sources of airborne particulates were the children’s activity during the lesson breaks with PMC up to 586μg/m3.Soft furniture,carpets in the classrooms and corridors were responsible for PMC up to 200μg/m3.Outdoor aerosol pollution(up to 18,170 particles/cm3)was higher for schools in city center.Elevated air pollution in classrooms also resulted from intermittent sources,such as construction work during classes(200-1000μg/m3)and petrol-powered lawn trimmers(up to 66,400 particles/cm3).Conclusion:The results of our survey show that even in a relatively low polluted region of Eastern Europe there are big differences in aerosol pollution within middle-sized city.Additional efforts are needed to improve air quality in schools:more frequent wet cleaning,monitoring the operation of ventilation systems,a ban on construction works during school year,on a use of sandblasting mechanisms in the neighborhood of schools.
基金This research was sponsored by the Research Council of Lithuania under contract S-MIP-21-30.Two of the authors are grateful for NATO SPS G5734 fellowships.
文摘We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15μm.An affordable two-stage ytterbium-doped yttrium aluminum garnet(Yb:YAG)chirped pulse amplifier provides more than 10 mJ,approximately 1.2 ps pulses at 1030 nm to pump a three-stage optical parametric chirped pulse amplifier(OPCPA)based on bismuth borate crystals and to drive the supercontinuum seed in the YAG crystal.The energy of the amplified pulses in the wavelength range of 1.95–2.4μm reached 2.25 mJ with a pump-tosignal conversion efficiency of approximately 25%in the last OPCPA stage.These pulses were compressed to 38 fs in a pair of Suprasil 300 glass prisms.
基金The work was supported by project No.18-09055Y and 20-08633X awarded by Czech Science FoundationThe research of I.M.,J.S.,T.J.-Y.D.,and N.M.B.is financed by the European Regional Development Fund and the state budget of the Czech Republic(project BIATRI,No.CZ.02.1.01/0.0/0.0/15_003/0000445,project HiLASE CoE,No.CZ.02.1.01/0.0/0.0/15_006/0000674,programme NPU I,project No.LO1602)+3 种基金The work was further supported by European Regional Development Fund,OP RDE,Project:“Carbon allotropes with rationalized nanointerfaces and nanolinks for environmental and biomedical applications”(No.CZ.02.1.01/0.0/0.0/16_026/0008382)The authors also acknowledge the assistance provided by the Research Infrastructures NanoEnviCz(No.LM2015073)supported by the Ministry of EducationYouth and Sports of the Czech Republic and the project Pro-NanoEnviCz(No.CZ.02.1.01/0.0/0.0/16_013/0001821)supported by the Ministry of EducationYouth and Sports of the Czech Republic and the European Union-European Structural and Investments Funds in the frame of Operational Programme Research Development and Education.
文摘Controlling the spatial distribution of functional groups on two-dimensional(2D)materials on a micrometer scale and below represents a fascinating opportunity to achieve anisotropic(opto)electronic properties of these materials.Periodic patterns of covalent functionalization can lead to pericxJic potentials in the monolayer;however,creating such superstructures is very challenging.Here,we describe an original approach to the periodic functionalization of graphene induced by substrate patterning using a pulsed laser.Laser-induced periodic surface structures(LIPSS)are produced on silicon wafers with thermally-grown oxide layers.The irradiation conditions for the formation of UPSS confined at the SiO2/Si interface have been unravelled.LIPSS imprint their periodicity to the reactivity of the monolayer graphene placed on the substrate via modulation of its local doping level.This method is clean,straightforward and scalable with high spatial resolution.
基金funding from European Social Fund(project No.09.3.3-LMT-K-712-01-0167)under a grant agreement with the Research Council of Lithuania(LMT)the funding by the Foundation For Polish Science,grant number MAB/2018/9.
文摘Structured light–electromagnetic waves with a strong spatial inhomogeneity of amplitude,phase,and polarization–has occupied far-reaching positions in both optical research and applications.Terahertz(THz)waves,due to recent innovations in photonics and nanotechnology,became so robust that it was not only implemented in a wide variety of applications such as communications,spectroscopic analysis,and non-destructive imaging,but also served as a low-cost and easily implementable experimental platform for novel concept illustration.In this work,we show that structured nonparaxial THz light in the form of Airy,Bessel,and Gaussian beams can be generated in a compact way using exclusively silicon diffractive optics prepared by femtosecond laser ablation technology.The accelerating nature of the generated structured light is demonstrated via THz imaging of objects partially obscured by an opaque beam block.Unlike conventional paraxial approaches,when a combination of a lens and a cubic phase(or amplitude)mask creates a nondiffracting Airy beam,we demonstrate simultaneous lensless nonparaxial THz Airy beam generation and its application in imaging system.Images of single objects,imaging with a controllable placed obstacle,and imaging of stacked graphene layers are presented,revealing hence potential of the approach to inspect quality of 2D materials.Structured nonparaxial THz illumination is investigated both theoretically and experimentally with appropriate extensive benchmarks.The structured THz illumination consistently outperforms the conventional one in resolution and contrast,thus opening new frontiers of structured light applications in imaging and inverse scattering problems,as it enables sophisticated estimates of optical properties of the investigated structures.
