The acidity of atmospheric aerosols influences fundamental physicochemical processes that affect climate and human health.We recently developed a novel and facilewater-probebased method for directly measuring of the p...The acidity of atmospheric aerosols influences fundamental physicochemical processes that affect climate and human health.We recently developed a novel and facilewater-probebased method for directly measuring of the pH for micrometer-size droplets,providing a promising technique to better understand aerosol acidity in the atmosphere.The complex chemical composition of fine particles in the ambient air,however,poses certain challenges to using a water-probe for pH measurement,including interference from interactions between compositions and the influence of similar compositions on water structure.To explore the universality of our method,it was employed to measure the pH of ammonium,nitrate,carbonate,sulfate,and chloride particles.The pH of particles covering a broad range(0–14)were accurately determined,thereby demonstrating that our method can be generally applied,even to alkaline particles.Furthermore,a standard spectral library was developed by integrating the standard spectra of common hydrated ions extracted through the waterprobe.The library can be employed to identify particle composition and overcome the spectral overlap problem resulting from similar effects.Using the spectral library,all ions were identified and their concentrations were determined,in turn allowing successful pH measurement of multicomponent(ammonium-sulfate-nitrate-chloride)particles.Insights into the synergistic effect of Cl^(–),NO_(3)^(–),and NH_(4)^(+)depletion obtained with our approach revealed the interplay between pH and volatile partitioning.Given the ubiquity of component partitioning and pH variation in particles,the water probemay provide a new perspective on the underlying mechanisms of aerosol aging and aerosol–cloud interaction.展开更多
Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface e...Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy（SEM）, micro-Raman spectroscopy（MRS）, and transmission electron microscopy（TEM） were applied to measure the geometric parameters of the multilayer structure. The relationship between the Raman spectrum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and crosssection residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was successfully obtained.展开更多
We developed a set of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus because of the scientific significance of in-situ Micro-Raman spectroscopy system under the high-pressure hydrothermal...We developed a set of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus because of the scientific significance of in-situ Micro-Raman spectroscopy system under the high-pressure hydrothermal condition.We used this system to measure the Raman spectrum of water-fluid and quartz crystal at the temperature ranging from 125 to 420℃.The signal-tonoise ratio of the Raman signal is good.展开更多
Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogen...Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography（XCT） and micro-Raman spectrometry to measure individual CaCO_3 particle morphology, with sizes ranging from 3.5–6.5 μm. Particle surface area and volume were calculated using a reconstruction method based on software threedimensional（3-D） rendering. The XCT was first validated with high-resolution fieldemission scanning electron microscopy（FE-SEM） to acquire accurate CaCO_3 particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual Ca CO3 particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.展开更多
It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and mi...It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.展开更多
To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices,Raman characterization and electrical transport measurement of 40-keV-proton irradiated...To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices,Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa_(2)Cu_(3)O_(7-x)(YBCO)thin films are carried out.From micro-Raman spectroscopy and x-ray diffraction studies,the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase.The results indicate that the defects induced in the conducting CuO_(2) planes,such as increased oxygen vacancies and interstitials,can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation,which is confirmed in the electrical transport measurements.Especially,zero-resistance temperature TC_(0) is not observed at a fluence of 10^(15)p/cm^(2).Furthermore,the variation of activation energy U_(0) can be explained by the plastic-flux creep theory,which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects.Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films.These disorders are likely to cause flux creep by thermally assisted flux flow,which may increase noise and reduce the precision of superconducting devices.展开更多
In this work, we are interesting in the measurement of thermal conductivity (on the surface and in-depth) of Porous silicon by the micro-Raman spectroscopy. This direct method (micro-Raman spectroscopy) enabled us to ...In this work, we are interesting in the measurement of thermal conductivity (on the surface and in-depth) of Porous silicon by the micro-Raman spectroscopy. This direct method (micro-Raman spectroscopy) enabled us to develop a systematic means of investigation of the morphology and the thermal conductivity of Porous silicon oxidized or no. The thermal conductivity is studied according to the parameters of anodization and fraction of silicon oxidized. Thermal transport in the porous silicon layers is limited by its porous nature and the blocking of transport in the silicon skeleton what supports its use in the thermal sensors.展开更多
Polarized micro-Raman spectra of a 0.65PbMgl/3Nb2/303 0.35PbTiO3 （0.65PMN-0.35PT） single crystal poled in the [001] direction are obtained in a wide frequency range （50 2000 cm^-1） at different temperatures. The b...Polarized micro-Raman spectra of a 0.65PbMgl/3Nb2/303 0.35PbTiO3 （0.65PMN-0.35PT） single crystal poled in the [001] direction are obtained in a wide frequency range （50 2000 cm^-1） at different temperatures. The best fit to the Raman spectrum at 77 K is achieved using 17 Lorenzians to convolute into it, and this is proved to be a reasonable fit. According to the group theory and selection rules of overtone and combinational modes, apart from the seven Raman modes that are from first-order Raman scattering, the remaining ones are attributed to being from second-order Raman scattering. A comparison between the experimental results and theoretical predictions shows that they are in satisfactory agreement with each other. Our results indicate that at 77 K the sample belongs to the rhombohedral symmetry with the C^53v（R3m） space group （Z = 1）. In our study, on heating, the 0.65PMN 0.35PT single crystal undergoes a rhombohedral → tetragonal → cubic phase transition sequence. The two phase transitions occur at 340 and 440 K, which correspond to the disappearance of the soft mode near 106 cm-1 recorded in VV polarization and the vanishing of the band around 780 cm^-1 in VH polarization, respectively.展开更多
The Darhib mine is one of the several talc deposits in the Hamata area of southeastern Egypt. Several specimens of minerals coming from this mine were subjected to complementary investigation by micro-Raman spectromet...The Darhib mine is one of the several talc deposits in the Hamata area of southeastern Egypt. Several specimens of minerals coming from this mine were subjected to complementary investigation by micro-Raman spectrometry and scanning electron microscopy. The difficulty in their identification is the appearance of most of them: they are all very small and only visible under the mineral binocular microscope(×10 - ×40). They appear as small crystals in fissures and holes and a visual determination on colour and crystal gives only a guess of what kind of mineral it could be. Therefore, only after analyzing them by micro-Raman and scanning electron microscopy it was possible to identify their structure and they can be divided in three main groups: one is quite generic and several minerals of different species were identified, such as quartz, talc, mottramite and chrysocolla, very common in the talc mine (these ones are Si-based minerals);the other one is constituted by four samples which are Zn and/or Cu rich, which means minerals of the rosasite or aurichalcite groups;the last group is constituted by two samples containing mainly Pb..展开更多
In the present work,we have synthesized samarium doped zinc oxide nanostructures(Zn1-xSmxO;x=0.00,0.02,0.04 and 0.06) via chemical precipitation method and studied their structural,morphological,optical and photocatal...In the present work,we have synthesized samarium doped zinc oxide nanostructures(Zn1-xSmxO;x=0.00,0.02,0.04 and 0.06) via chemical precipitation method and studied their structural,morphological,optical and photocatalytic properties.X-ray diffraction(XRD) patterns,PL and Raman spectra results indicate that the undoped and Sm-doped ZnO nanostructures are crystallized in a hexagonal wurtzite structure.FESEM images show that the morphology of the sample changes from cubical to hexagonal nanostructures with increase in Sm3+doping concentration.The EDX spectra confirm the incorporation of Sm3+ion in ZnO.The influence of Sm3+doping on the structure,morphology,absorption,emission and photocatalytic activity of ZnO nanostructures were investigated systematically.The addition of Sm3+ion leads to a red shift in the optical energy band gap from 3.19 to 2.67 eV and hence,increases the visible light absorption ability.The presence of E2(H) and E1(LO) modes in microRaman spectra confirms the crystallinity and defects in the samples.The detailed photocatalytic experiments reveal that Sm-doped ZnO nanostructures show the maximum photodegradation efficiency for Methylene blue(MB) dye for x=0.04,i,e.,94.94%,under visible light irradiation.The photocatalytic efficiency improves by 6.98 times when ZnO is doped with rare earth metal ion(Sm3+) and is a potential candidate for practical applications.The investigation demonstrates that as-synthesized nano-sized photocatalysts act as an efficient photocatalyst for the degradation of MB dye.展开更多
This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)we...This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)were loaded with cationic corrosion inhibitors Ce 3+/Zr 4+.These nanocontainers were dispersed in hybrid organic-inorganic sol-gel matrix sol.Coating was applied on magnesium alloy AZ91D using the sols containing modified and unmodified nanocontainers employing the dip coating method and cured at 130℃for 1 h in air.Corrosion resistance of coated/uncoated substrates were analyzed using electrochemical impedance spectroscopy,potentiodynamic polarization and weight loss measurements after exposure to 3.5 wt%NaCl solution for varying time durations between 24 h to 120 h.Self-healing ability of coatings was evaluated by micro-Raman spectroscopy after 120 h exposure to 3.5 wt%NaCl solution.Coatings generated after dispersion of corrosion inhibitor loaded clay in hybrid sol-gel matrix have shown more promising corrosion resistance when compared to just the sol-gel matrix coatings,after prolonged exposure to corrosive environment.展开更多
During the winter period（January–March 2016）, the total suspended particles（TSP） and particulate matter smaller than 2.5 μm（PM2.5） were characterized by the application of various analytical techniques in four...During the winter period（January–March 2016）, the total suspended particles（TSP） and particulate matter smaller than 2.5 μm（PM2.5） were characterized by the application of various analytical techniques in four zones of the Metropolitan Area of Monterrey in Mexico. To evaluate the seasonal variation of some elements in the particulate matter, the results of this study were compared with those obtained during the summer season（July–September 2015）. The speciation of the C_（1s） signal by X-ray photoelectron spectroscopy revealed the contribution of aromatic and aliphatic hydrocarbons as the main components in both seasons. Conversely, carboxylic groups associated with biogenic emissions were detected only in winter. The percentages of SO_4^（2-） ions were lower in winter, possibly caused by the decrease in the solar radiation, and relative humidity recorded. The results of the ICP analysis revealed that Fe, Zn and Cu were the most abundant metals in both TSP and PM2.5 in the two seasons. There were significant seasonal variations for concentrations of As, Ni and Zn in the urban area and for Fe, As, Cd, Ni and Zn in the industrial zone. This was attributed to the greater burning of fuels as well as to an increase in vehicular traffic, the effect of thermal inversion and changes in some meteorological parameters. The results of the sequential microanalysis by Raman spectroscopy and SEM/EDS allowed observation of deposits of carbonaceous material on the particles and to perform the speciation of particles rich in Fe and Pb, which helped infer their possible emission sources.展开更多
We propose an experimental approach for investigation of the polycrystalline deformation behaviour at a grain scale. The technique is characterized by the joint application of micro material testing systems and the in...We propose an experimental approach for investigation of the polycrystalline deformation behaviour at a grain scale. The technique is characterized by the joint application of micro material testing systems and the intragranular deformation analysis methods, It is attempting to map the deformation evolution at grain scale during the elastic and plastic deformations of polycrystalline specimens.展开更多
Residual stress evolution regularity in thermal barrier ceramic coatings （TBCs） under different cycles of thermal shock loading of 1 100℃ was investi- gated by the microscopic digital image correlation （DIC） and ...Residual stress evolution regularity in thermal barrier ceramic coatings （TBCs） under different cycles of thermal shock loading of 1 100℃ was investi- gated by the microscopic digital image correlation （DIC） and micro-Raman spec- troscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress under- goes three distinct stages： a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1 100℃, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide （TGO） layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.展开更多
Rock fragments from the deepest parts of a buried hydrothermal system belonging to the Mesozoic Tethys Ocean entered as xenoliths in a Miocenic diatreme,hence brought to the surface,in the Hyblean Plateau(Sicily).Some...Rock fragments from the deepest parts of a buried hydrothermal system belonging to the Mesozoic Tethys Ocean entered as xenoliths in a Miocenic diatreme,hence brought to the surface,in the Hyblean Plateau(Sicily).Some xenoliths consist of strongly serpentinized ultramafic rocks bearing blebs of abiotic organic matter,where clusters of amorphous carbon nanoparticles,including nanodiamonds,are immersed.Such an occurrence conjures up established hypotheses that diamond surfaces are suitable catalytic platforms stimulating the assemblage of complex bio-organic molecules relevant to the emergence of life on Earth.The appearance of bio-organic molecules under primitive Earth conditions is one of the major unsolved questions on the origin of life.Here we report new micro-Raman spectra on blebs of abiotic organic matter from a selected xenolith.Diamond bands were related to hydrogenated nanocrystalline diamonds,with size of nearly 1-1.6 nm,formed from organics at low pressures and temperatures.In particular,diamond surfaces can give rise to crystalline interfacial water layers that may have played a fundamental role in the early biosphere evolution as a good medium for rapidly transporting positive charges in the form of hydrated protons.Nowadays,proton gradients in alkaline hydrothermal vents along oceanic ridges are generally viewed as key pre-biotic factors.In general,serpentinites span the entire geological record,including prebiotic times.These hydrous ultramafic rocks often display evidence of abiotic carbon species,both organic and inorganic,including nanodiamonds,being also capable to give rise to chemiosmotic processes and proton gradients necessary to the organisms,such as the"Last Universal Common Ancestor"(LUCA),in the prebiotic Earth.展开更多
Mechanical properties of micro-structured porous silicon film （PS） were studied combining X-ray diffraction with micro-Raman spectroscopy. The micro-structured porous silicon samples with different porosities rangin...Mechanical properties of micro-structured porous silicon film （PS） were studied combining X-ray diffraction with micro-Raman spectroscopy. The micro-structured porous silicon samples with different porosities ranging from 30.7700 to 96.2500 were obtained by chemical etching. Lattice parameters of the samples were measured using X-ray diffraction and its maximal change is up to （1.000.） This lattice mismatch with the bulk silicon substrate may introduce residual stress to the porous film. The residual stress measurement by micro-Raman spectroscopy reveals that the maximum of tensile residual stress has reached GPa level in the porous film. Moreover, the lattice mismatch and its corresponding residual stress are increasing with the porosity of PS, but average （elastic） modulus is about 14.5 GPa, one order of magnitude lower than that of substrate Si. The mechanical properties of PS have a close relation with its micro-pore structure.展开更多
The potential of Confocal micro Raman spectroscopy in the quantitative analysis of pesticide(Chlorpyrifos,Omethoate)residues on orange surface is investigated in this work.Quantitative analysis models were established...The potential of Confocal micro Raman spectroscopy in the quantitative analysis of pesticide(Chlorpyrifos,Omethoate)residues on orange surface is investigated in this work.Quantitative analysis models were established by partial least squares(PLS)using different preprocessing methods(Smoothing,First derivative,MSC,Baseline)for pesticide residues.For pesticide resi-dues,the higher correlation coefficients(r)is 0.972 and 0.943,the root mean square error of prediction(RMSEP)is 2.05%and 2.36%,respectively.It is therefore clear that Confocal micro-Raman spectroscopy techniques enable rapid,nondestructive and reliable measurements,so Raman spectrometry appears to be a prormising tool for pesticide residues.展开更多
In this paper, TitaiJum dioxide （TiO2） rutile single crystal was irradiated by infrared femtosecond laser pulses with repetition rate of 250 kHz. For a P-polarized femtosecond laser, the periodic nanograting structu...In this paper, TitaiJum dioxide （TiO2） rutile single crystal was irradiated by infrared femtosecond laser pulses with repetition rate of 250 kHz. For a P-polarized femtosecond laser, the periodic nanograting structure on the ablation crater surface was formed . The periodicity is much less than the laser wavelength. The direction of nanograting alignment depends on the polarization laser beam. Micro-Raman spectra show that the intensity of Eg Raman vibrating mode of rutile phase increases and that of Alg Raman vibrating mode decreases apparently within the ablation crater. With the increase of irradiation time and laser average power, the Raman vibrating modes of anatase phase emerged. Rutile phase of TiO2 single crystal is partly transformed into anatase phase.展开更多
The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallo...The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallographic observation results showed that the carbon steel was constituted of ferrite and some pearlite. The tensile test results indicated that the corroded rebar presented low strength and elongation. In addition, the fracture surface of the rebar in the tensile test displayed dimple fracture behavior. The Raman spectroscopy results indicated that corrosion products at the general corrosion zone were obviously different from those at the localized corrosion zone. The rust layer at the general corrosion zone was composed of goethite （α-FeOOH）, magnetite （Fe304）, and hematite （α-Fe203）, while that of the pitting zone was made of feroxyhyte （δ-FeOOH）, goethite （α-FeOOH）, and hematite （α-Fe203）. However, the general tendencies that the corrosion products were constituted of a mix of oxides and hydroxides, the oxides mainly existed in the internal part and the hydroxides more presented in the external layer were observed.展开更多
基金supported by the National Natural Science Foundation of China(No.91844000)China Postdoctoral Science Foundation(No.2020M670048).
文摘The acidity of atmospheric aerosols influences fundamental physicochemical processes that affect climate and human health.We recently developed a novel and facilewater-probebased method for directly measuring of the pH for micrometer-size droplets,providing a promising technique to better understand aerosol acidity in the atmosphere.The complex chemical composition of fine particles in the ambient air,however,poses certain challenges to using a water-probe for pH measurement,including interference from interactions between compositions and the influence of similar compositions on water structure.To explore the universality of our method,it was employed to measure the pH of ammonium,nitrate,carbonate,sulfate,and chloride particles.The pH of particles covering a broad range(0–14)were accurately determined,thereby demonstrating that our method can be generally applied,even to alkaline particles.Furthermore,a standard spectral library was developed by integrating the standard spectra of common hydrated ions extracted through the waterprobe.The library can be employed to identify particle composition and overcome the spectral overlap problem resulting from similar effects.Using the spectral library,all ions were identified and their concentrations were determined,in turn allowing successful pH measurement of multicomponent(ammonium-sulfate-nitrate-chloride)particles.Insights into the synergistic effect of Cl^(–),NO_(3)^(–),and NH_(4)^(+)depletion obtained with our approach revealed the interplay between pH and volatile partitioning.Given the ubiquity of component partitioning and pH variation in particles,the water probemay provide a new perspective on the underlying mechanisms of aerosol aging and aerosol–cloud interaction.
基金supported by the National Basic Research Program of China (Grant 2012CB937500)the National Natural Science Foundation of China (Grants 11422219, 11227202, 11372217, 11272232)+1 种基金the Program for New Century Excellent Talents in University (Grant NCET-13)China Scholarship Council (201308120092)
文摘Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy（SEM）, micro-Raman spectroscopy（MRS）, and transmission electron microscopy（TEM） were applied to measure the geometric parameters of the multilayer structure. The relationship between the Raman spectrum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and crosssection residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was successfully obtained.
基金supported by the National Key R&D Program of China(Grant No.2016YFC0600104)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB 18010401)。
文摘We developed a set of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus because of the scientific significance of in-situ Micro-Raman spectroscopy system under the high-pressure hydrothermal condition.We used this system to measure the Raman spectrum of water-fluid and quartz crystal at the temperature ranging from 125 to 420℃.The signal-tonoise ratio of the Raman signal is good.
基金supported by the Chinese Ministry of Science and Technology(No.2008AA062503)the National Natural Science Foundation Committee of China(Nos.41421064,20637020)the China Postdoctoral Science Foundation(No.20100470166)
文摘Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography（XCT） and micro-Raman spectrometry to measure individual CaCO_3 particle morphology, with sizes ranging from 3.5–6.5 μm. Particle surface area and volume were calculated using a reconstruction method based on software threedimensional（3-D） rendering. The XCT was first validated with high-resolution fieldemission scanning electron microscopy（FE-SEM） to acquire accurate CaCO_3 particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual Ca CO3 particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.
基金This work is supported by the National Natural Science Foundation of China （Grant Nos. 60336010 ＆ 90401001）973 Program （Grant No. TG 2000036603）the Student Innovation Program of CAS （No. 1731000500010）.
文摘It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.
基金Project supported by the National Natural Science Foundation of China(Grant No.61473023)the Aerospace Science and Technology Innovation Fund,CASCInternational S&T Cooperation Program of China(ISTCP)(Grant No.2015DFR80190)
文摘To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices,Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa_(2)Cu_(3)O_(7-x)(YBCO)thin films are carried out.From micro-Raman spectroscopy and x-ray diffraction studies,the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase.The results indicate that the defects induced in the conducting CuO_(2) planes,such as increased oxygen vacancies and interstitials,can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation,which is confirmed in the electrical transport measurements.Especially,zero-resistance temperature TC_(0) is not observed at a fluence of 10^(15)p/cm^(2).Furthermore,the variation of activation energy U_(0) can be explained by the plastic-flux creep theory,which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects.Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films.These disorders are likely to cause flux creep by thermally assisted flux flow,which may increase noise and reduce the precision of superconducting devices.
文摘In this work, we are interesting in the measurement of thermal conductivity (on the surface and in-depth) of Porous silicon by the micro-Raman spectroscopy. This direct method (micro-Raman spectroscopy) enabled us to develop a systematic means of investigation of the morphology and the thermal conductivity of Porous silicon oxidized or no. The thermal conductivity is studied according to the parameters of anodization and fraction of silicon oxidized. Thermal transport in the porous silicon layers is limited by its porous nature and the blocking of transport in the silicon skeleton what supports its use in the thermal sensors.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10674171 and 10874236)
文摘Polarized micro-Raman spectra of a 0.65PbMgl/3Nb2/303 0.35PbTiO3 （0.65PMN-0.35PT） single crystal poled in the [001] direction are obtained in a wide frequency range （50 2000 cm^-1） at different temperatures. The best fit to the Raman spectrum at 77 K is achieved using 17 Lorenzians to convolute into it, and this is proved to be a reasonable fit. According to the group theory and selection rules of overtone and combinational modes, apart from the seven Raman modes that are from first-order Raman scattering, the remaining ones are attributed to being from second-order Raman scattering. A comparison between the experimental results and theoretical predictions shows that they are in satisfactory agreement with each other. Our results indicate that at 77 K the sample belongs to the rhombohedral symmetry with the C^53v（R3m） space group （Z = 1）. In our study, on heating, the 0.65PMN 0.35PT single crystal undergoes a rhombohedral → tetragonal → cubic phase transition sequence. The two phase transitions occur at 340 and 440 K, which correspond to the disappearance of the soft mode near 106 cm-1 recorded in VV polarization and the vanishing of the band around 780 cm^-1 in VH polarization, respectively.
文摘The Darhib mine is one of the several talc deposits in the Hamata area of southeastern Egypt. Several specimens of minerals coming from this mine were subjected to complementary investigation by micro-Raman spectrometry and scanning electron microscopy. The difficulty in their identification is the appearance of most of them: they are all very small and only visible under the mineral binocular microscope(×10 - ×40). They appear as small crystals in fissures and holes and a visual determination on colour and crystal gives only a guess of what kind of mineral it could be. Therefore, only after analyzing them by micro-Raman and scanning electron microscopy it was possible to identify their structure and they can be divided in three main groups: one is quite generic and several minerals of different species were identified, such as quartz, talc, mottramite and chrysocolla, very common in the talc mine (these ones are Si-based minerals);the other one is constituted by four samples which are Zn and/or Cu rich, which means minerals of the rosasite or aurichalcite groups;the last group is constituted by two samples containing mainly Pb..
文摘In the present work,we have synthesized samarium doped zinc oxide nanostructures(Zn1-xSmxO;x=0.00,0.02,0.04 and 0.06) via chemical precipitation method and studied their structural,morphological,optical and photocatalytic properties.X-ray diffraction(XRD) patterns,PL and Raman spectra results indicate that the undoped and Sm-doped ZnO nanostructures are crystallized in a hexagonal wurtzite structure.FESEM images show that the morphology of the sample changes from cubical to hexagonal nanostructures with increase in Sm3+doping concentration.The EDX spectra confirm the incorporation of Sm3+ion in ZnO.The influence of Sm3+doping on the structure,morphology,absorption,emission and photocatalytic activity of ZnO nanostructures were investigated systematically.The addition of Sm3+ion leads to a red shift in the optical energy band gap from 3.19 to 2.67 eV and hence,increases the visible light absorption ability.The presence of E2(H) and E1(LO) modes in microRaman spectra confirms the crystallinity and defects in the samples.The detailed photocatalytic experiments reveal that Sm-doped ZnO nanostructures show the maximum photodegradation efficiency for Methylene blue(MB) dye for x=0.04,i,e.,94.94%,under visible light irradiation.The photocatalytic efficiency improves by 6.98 times when ZnO is doped with rare earth metal ion(Sm3+) and is a potential candidate for practical applications.The investigation demonstrates that as-synthesized nano-sized photocatalysts act as an efficient photocatalyst for the degradation of MB dye.
基金financial sup-port from SERB,DST for the funding provided through grant number SB/S3/ME/007/2014.
文摘This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)were loaded with cationic corrosion inhibitors Ce 3+/Zr 4+.These nanocontainers were dispersed in hybrid organic-inorganic sol-gel matrix sol.Coating was applied on magnesium alloy AZ91D using the sols containing modified and unmodified nanocontainers employing the dip coating method and cured at 130℃for 1 h in air.Corrosion resistance of coated/uncoated substrates were analyzed using electrochemical impedance spectroscopy,potentiodynamic polarization and weight loss measurements after exposure to 3.5 wt%NaCl solution for varying time durations between 24 h to 120 h.Self-healing ability of coatings was evaluated by micro-Raman spectroscopy after 120 h exposure to 3.5 wt%NaCl solution.Coatings generated after dispersion of corrosion inhibitor loaded clay in hybrid sol-gel matrix have shown more promising corrosion resistance when compared to just the sol-gel matrix coatings,after prolonged exposure to corrosive environment.
基金the Consejo Nacional de Ciencia y Tecnología(CONACyT)for the scholarship provided(No.573607)
文摘During the winter period（January–March 2016）, the total suspended particles（TSP） and particulate matter smaller than 2.5 μm（PM2.5） were characterized by the application of various analytical techniques in four zones of the Metropolitan Area of Monterrey in Mexico. To evaluate the seasonal variation of some elements in the particulate matter, the results of this study were compared with those obtained during the summer season（July–September 2015）. The speciation of the C_（1s） signal by X-ray photoelectron spectroscopy revealed the contribution of aromatic and aliphatic hydrocarbons as the main components in both seasons. Conversely, carboxylic groups associated with biogenic emissions were detected only in winter. The percentages of SO_4^（2-） ions were lower in winter, possibly caused by the decrease in the solar radiation, and relative humidity recorded. The results of the ICP analysis revealed that Fe, Zn and Cu were the most abundant metals in both TSP and PM2.5 in the two seasons. There were significant seasonal variations for concentrations of As, Ni and Zn in the urban area and for Fe, As, Cd, Ni and Zn in the industrial zone. This was attributed to the greater burning of fuels as well as to an increase in vehicular traffic, the effect of thermal inversion and changes in some meteorological parameters. The results of the sequential microanalysis by Raman spectroscopy and SEM/EDS allowed observation of deposits of carbonaceous material on the particles and to perform the speciation of particles rich in Fe and Pb, which helped infer their possible emission sources.
基金Supported by National Natural Science Foundation of China under Grant Nos 10072031, 10372049 and 10232030, the National Basic Research and Development Programme of China Grant No 2004CB619304, and the Central Laboratory of Strength and Vibration of Tsinghua University.
文摘We propose an experimental approach for investigation of the polycrystalline deformation behaviour at a grain scale. The technique is characterized by the joint application of micro material testing systems and the intragranular deformation analysis methods, It is attempting to map the deformation evolution at grain scale during the elastic and plastic deformations of polycrystalline specimens.
基金supported by the National Natural Science Foundation of China(91216301,11072033,11232008,and 11372037)the Program for New Century Excellent Talents in University(NCET-12-0036)the Natural Science Foundation of Beijing,China(3122027)
文摘Residual stress evolution regularity in thermal barrier ceramic coatings （TBCs） under different cycles of thermal shock loading of 1 100℃ was investi- gated by the microscopic digital image correlation （DIC） and micro-Raman spec- troscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress under- goes three distinct stages： a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1 100℃, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide （TGO） layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.
文摘Rock fragments from the deepest parts of a buried hydrothermal system belonging to the Mesozoic Tethys Ocean entered as xenoliths in a Miocenic diatreme,hence brought to the surface,in the Hyblean Plateau(Sicily).Some xenoliths consist of strongly serpentinized ultramafic rocks bearing blebs of abiotic organic matter,where clusters of amorphous carbon nanoparticles,including nanodiamonds,are immersed.Such an occurrence conjures up established hypotheses that diamond surfaces are suitable catalytic platforms stimulating the assemblage of complex bio-organic molecules relevant to the emergence of life on Earth.The appearance of bio-organic molecules under primitive Earth conditions is one of the major unsolved questions on the origin of life.Here we report new micro-Raman spectra on blebs of abiotic organic matter from a selected xenolith.Diamond bands were related to hydrogenated nanocrystalline diamonds,with size of nearly 1-1.6 nm,formed from organics at low pressures and temperatures.In particular,diamond surfaces can give rise to crystalline interfacial water layers that may have played a fundamental role in the early biosphere evolution as a good medium for rapidly transporting positive charges in the form of hydrated protons.Nowadays,proton gradients in alkaline hydrothermal vents along oceanic ridges are generally viewed as key pre-biotic factors.In general,serpentinites span the entire geological record,including prebiotic times.These hydrous ultramafic rocks often display evidence of abiotic carbon species,both organic and inorganic,including nanodiamonds,being also capable to give rise to chemiosmotic processes and proton gradients necessary to the organisms,such as the"Last Universal Common Ancestor"(LUCA),in the prebiotic Earth.
文摘Mechanical properties of micro-structured porous silicon film （PS） were studied combining X-ray diffraction with micro-Raman spectroscopy. The micro-structured porous silicon samples with different porosities ranging from 30.7700 to 96.2500 were obtained by chemical etching. Lattice parameters of the samples were measured using X-ray diffraction and its maximal change is up to （1.000.） This lattice mismatch with the bulk silicon substrate may introduce residual stress to the porous film. The residual stress measurement by micro-Raman spectroscopy reveals that the maximum of tensile residual stress has reached GPa level in the porous film. Moreover, the lattice mismatch and its corresponding residual stress are increasing with the porosity of PS, but average （elastic） modulus is about 14.5 GPa, one order of magnitude lower than that of substrate Si. The mechanical properties of PS have a close relation with its micro-pore structure.
基金supported by National Science and Technology Support Program of China (31160250,61178036)Ganpo excellence project 555 Talent Plan of Jiangxi Province (2011-64)Center of Photoelctric Detection Technology Engineering of Jiangxi Province (2012-155).
文摘The potential of Confocal micro Raman spectroscopy in the quantitative analysis of pesticide(Chlorpyrifos,Omethoate)residues on orange surface is investigated in this work.Quantitative analysis models were established by partial least squares(PLS)using different preprocessing methods(Smoothing,First derivative,MSC,Baseline)for pesticide residues.For pesticide resi-dues,the higher correlation coefficients(r)is 0.972 and 0.943,the root mean square error of prediction(RMSEP)is 2.05%and 2.36%,respectively.It is therefore clear that Confocal micro-Raman spectroscopy techniques enable rapid,nondestructive and reliable measurements,so Raman spectrometry appears to be a prormising tool for pesticide residues.
基金Project supported by Shanghai Leading Academic Discipline Project, China （Grant No T0104）, the Shanghai Nano-technology Promotion Center and Science ＆ Technology of Shanghai Municipality, China （Grant No 0652nm005）, Science Foundation of Shanghai Municipal Commission Education and Science and Technology Commission of Shanghai Municipal, China （Grant No 06PJ14042）.
文摘In this paper, TitaiJum dioxide （TiO2） rutile single crystal was irradiated by infrared femtosecond laser pulses with repetition rate of 250 kHz. For a P-polarized femtosecond laser, the periodic nanograting structure on the ablation crater surface was formed . The periodicity is much less than the laser wavelength. The direction of nanograting alignment depends on the polarization laser beam. Micro-Raman spectra show that the intensity of Eg Raman vibrating mode of rutile phase increases and that of Alg Raman vibrating mode decreases apparently within the ablation crater. With the increase of irradiation time and laser average power, the Raman vibrating modes of anatase phase emerged. Rutile phase of TiO2 single crystal is partly transformed into anatase phase.
基金Funded by the National Natural Science Foundation of China(51301060,51210001)the 111 Project(B12032)+1 种基金the Key Laboratory of Advanced Civil Engineering Materials(Tongji University),Ministry of Educationthe Fundamental Research Funds for the Central Universities(No.2013B03514)
文摘The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallographic observation results showed that the carbon steel was constituted of ferrite and some pearlite. The tensile test results indicated that the corroded rebar presented low strength and elongation. In addition, the fracture surface of the rebar in the tensile test displayed dimple fracture behavior. The Raman spectroscopy results indicated that corrosion products at the general corrosion zone were obviously different from those at the localized corrosion zone. The rust layer at the general corrosion zone was composed of goethite （α-FeOOH）, magnetite （Fe304）, and hematite （α-Fe203）, while that of the pitting zone was made of feroxyhyte （δ-FeOOH）, goethite （α-FeOOH）, and hematite （α-Fe203）. However, the general tendencies that the corrosion products were constituted of a mix of oxides and hydroxides, the oxides mainly existed in the internal part and the hydroxides more presented in the external layer were observed.
