In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural a...In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.展开更多
Over the past several decades,much research effort has been dedicated to the study of optical windows,with two primary themes emerging as key focuses.The first of these centers on investigating the optical properties ...Over the past several decades,much research effort has been dedicated to the study of optical windows,with two primary themes emerging as key focuses.The first of these centers on investigating the optical properties of typical transparent single crystals under shock or ramp compression,which helps in the selection of appropriate optical windows for high-pressure experiments.The second involves the exploration of novel optical windows,particularly transparent polycrystalline ceramics,which not only match the shock impedance of the samples,but also preserve transparency under dynamic compression.In this study,we first integrate existing research on the evolution of optical properties in transparent single crystals and polycrystalline ceramics subjected to shock or ramp loading,proposing a mechanism that links mesoscopic damage to macroscopic optical transparency.Subsequently,through a systematic integration of experiments and computational analyses on polycrystalline transparent ceramics,we demonstrate that shock transparency can be enhanced by optimizing grain size and that shock impedance can be designed via compositional tuning.Notably,our results reveal that nano-grained MgAl_(2)O_(4) ceramics exhibit outstanding optical transparency under high shock pressures,highlighting a promising strategy for designing optical windows that retain transparency under extreme dynamic loading conditions.展开更多
Density functional theory(DFT)studies were performed on the lattice parameters,electronic band structure,and optical constants under pressure up to 20 GPa in order to obtain insight into the electronic and optical pro...Density functional theory(DFT)studies were performed on the lattice parameters,electronic band structure,and optical constants under pressure up to 20 GPa in order to obtain insight into the electronic and optical properties of LiZnAs.The calculated results show LiZnAs is a semiconductor with a direct gap of 0.86 eV,which is smaller than the experimental value 1.1 eV.It also indicates that the structural parameters such as lattice parameters and cell volume show inverse relation to the pressure and shows smooth decreasing behavior from 0 to 20 GPa.Meanwhile,the pressure dependence of the electronic band structure,density of states and partial density of states of LiZnAs up to 20 GPa were presented.And we found that the band gap increased with the pressure.Moreover,the evolution of the dielectric function,absorption coefficient a(w),reflectivity R(w),the refractive index n(w),and the extinction coefficient k(w)of LiZnAs under pressure were presented.According to our work,we found that the optical properties of LiZnAs undergo a blue shift with increasing pressure.These results suggest technological applications of such materials in extreme environments.展开更多
Pyrochlore structure La2Sn2O7：Eu3＋ microcrystals with uniform octahedron shape were successfully synthesized via a hydrothermal route at 180 °C for 36 h. The crystal structure, particle size, morphologies, and ...Pyrochlore structure La2Sn2O7：Eu3＋ microcrystals with uniform octahedron shape were successfully synthesized via a hydrothermal route at 180 °C for 36 h. The crystal structure, particle size, morphologies, and optical properties of the as-synthesized products were investigated by XRD, TEM, SEM, EDS, FT-IR, Raman spectroscopy and PL. The effects of pH of precursor solution, precursor concentration, reaction temperature, and time were investigated. The results reveal that pH of the precursor solution not only plays an important role in determining the phase of the as-synthesized products, but also has a significant influence on the morphologies of the samples. High-quality and uniform octahedrons with an average size of about 700 nm could be easily obtained at the pH value of 12. The possible formation mechanism of octahedral-like La2Sn2O7：Eu3＋ microcrystals was briefly proposed. The photoluminescence spectra show that La2Sn2O7：Eu3＋ micro-octahedra display stronger emission in the range of 582-592 nm compared with the samples with other shapes.展开更多
Monodisperse zinc phosphate microspheres were synthesized by a facile solvothermal method in the presence of oleic acid.X-ray powder diffraction（XRD）,Fourier transform infrared spectrum（FT-IR）,emission scanning el...Monodisperse zinc phosphate microspheres were synthesized by a facile solvothermal method in the presence of oleic acid.X-ray powder diffraction（XRD）,Fourier transform infrared spectrum（FT-IR）,emission scanning electron microscopy（SEM）,and energy dispersive X-ray spectrum（EDX） were used to characterize the microstructures and morphologies of the as-obtained zinc phosphate samples.The experimental results indicate that the zinc phosphate products are well crystallized,and the morphologies of the samples can be easily controlled by the elaborate choice of oleic acid addition and the content of NaOH.Furthermore,self-activated luminescent properties of the products are observed.The as-obtained samples show an intense blue emission under a long-wavelength UV light excitation of 400 nm.The possible luminescent mechanism may be ascribed to the carbon-related surface impurities or defects.展开更多
The optical absorption of large molecular compounds HULIS(humic-like substances)can significantly impact the aerosol light absorption and radiative forcing,influencing cloud condensation nuclei formation and thus the ...The optical absorption of large molecular compounds HULIS(humic-like substances)can significantly impact the aerosol light absorption and radiative forcing,influencing cloud condensation nuclei formation and thus the climate and atmospheric environment.This study collected aerosol(PM_(2.5))samples from the summit of Mount Tai in North China to investigate the concentration,molecular composition,and optical properties of HULIS.The average concentration of HULIS in the PM_(2.5) in this study was 1.26±0.54μg/m^(3),comprising for 56%of the water-soluble organic carbon(WSOC),with levels lower than urban areas but higher than other mountainous regions.Mass spectrometry revealed that CHO and CHON components,with high aromaticity and phenolic groups,are major contributors to absorption and fluorescence.These results indicate that HULIS is mainly composed of lignin and proteins/amino sugars,derived from combustion and secondary formation,and possesses a high light absorption capacity(withMAE365(mass absorption efficiency)and AAE(A˚ngstrom exponent)indices of 0.62m^(2)/g and 4.99,respectively).Parallel factor analysis identified three fluorescence components of HULIS,with proportions of 60.8%for less oxygen humic-like substances,21.0%for high oxygen humic-like substances,and 18.2%for protein-like substances.Our study highlights the significance of the light-absorbing capacity and secondary formation of HULIS at Mount Tai,laying the groundwork for investigation into the climate effects,formation mechanisms,and sources of HULIS generation.展开更多
ZnS ∶Cu nanoparticles were prepared by using microemulsion method at room temperature. The size of the particles is 2-8 nm by transmission electron microscopy (TEM) and dynamic light scattering (DLS) technique. X-ray...ZnS ∶Cu nanoparticles were prepared by using microemulsion method at room temperature. The size of the particles is 2-8 nm by transmission electron microscopy (TEM) and dynamic light scattering (DLS) technique. X-ray diffraction analysis shows that the particles are cubic crystal structure, the same structure as the bulk ZnS materials. Ultraviolet absorption demonstrates an increased bandgap due to quantum confinement effect. Photoluminescence spectrum shows there is a single green emission band at 482 nm.展开更多
ZnO films grown by metal organic chemical vapor deposition at atmospheric pressure are annealed at 850℃ ,with the film surfaces exposed to air or covered by a sapphire wafer. The optical properties of the as-grown an...ZnO films grown by metal organic chemical vapor deposition at atmospheric pressure are annealed at 850℃ ,with the film surfaces exposed to air or covered by a sapphire wafer. The optical properties of the as-grown and the annealed samples are studied by photoluminescence （PL） spectroscopy. It is found that the air-exposure annealing effectively removes the hydrogen impurities from the ZnO films but greatly increases the deep-level emission. In the surface-covered annealed sample, an elimination of the hydrogen impurities is also observed, and the deep-level emission disappears completely. The free exciton emission is significantly enhanced in the ZnO film after surface-covered annealing.展开更多
Aerosol observational data at 8 ground-based observation sites in the Chinese Sun Hazemeter Network （CSHNET） were analyzed to characterize the optical properties of aerosol particles during the strong dust storm of ...Aerosol observational data at 8 ground-based observation sites in the Chinese Sun Hazemeter Network （CSHNET） were analyzed to characterize the optical properties of aerosol particles during the strong dust storm of 16-21 April 2005. The observational aerosol optical depth （AOD） increased significantly during this dust storm at sites in Beijing city （86%）, Beijing forest （84%）, Xianghe （13%）, Shapotou （27%）, Shenyang （47%）, Shanghai （23%）, and Jiaozhou Bay （24%）. The API （air pollution index） in Beijing and Tianjin also had a similar rise during the dust storm, while the Angstrhm exponent （a） declined evidently at sites in Beijing city （21%）, Beijing forest （39%）, Xianghe （19%）, Ordos （77%）, Shapotou （50%）, Shanghai （12%）, and Jiaozhou Bay （21%）, respectively. Furthermore, The observational AOD and a demonstrated contrary trends during M1 storm stages （pre-dust storm, dust storm, and post-dust storm）, with the AOD indicating an obvious ＂Valley Peak-Valley＂ pattern of variation, while a demonstrated a ＂Peak-Valley- Peak＂ pattern. In addition, the dust module in a regional climate model （RegCM3） simulated the dust storm occurrence and track accurately and RegCM3 was able to basically simulate the trends in AOD. The simulation results for the North China stations were the best, and the simulation for dust-source stations was on the high side, while the simulation was on the low side for coastal sites.展开更多
The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China, acquired through a CE318 sunphotometer of the ground-based Aerosol Robotic Network （AERONET）, are analyzed. The se...The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China, acquired through a CE318 sunphotometer of the ground-based Aerosol Robotic Network （AERONET）, are analyzed. The seasonal variations in the aerosol optical properties are examined. The effect of meteorological elements （pressure, temperature, water vapor pressure, relative humidity and wind speed） on the aerosol optical properties is also studied. Then, the sources and optical properties under two different cases, a dust event and a pollution event, are compared. The results show that the high aerosol optical depth （AOD） found in Yulin was mostly attributed to the occurrence of dust events in spring from the Mu Us desert and deserts of West China and Mongolia, as well as the impacts of anthropogenic pollutant particles from the middle part of China in the other seasons. The seasonal variation and the probability distribution of the radiative forcing and the radiative forcing efficiency at the surface and the top of the atmosphere are analyzed and regressed using the linear and Gaussian regression methods.展开更多
There are large uncertainties in the quantitative assessment of radiative effects due to atmospheric dust aerosol. The optical properties contribute much to those uncertainties. The authors perform several sensitivity...There are large uncertainties in the quantitative assessment of radiative effects due to atmospheric dust aerosol. The optical properties contribute much to those uncertainties. The authors perform several sensitivity experiments to estimate the impacts of optical characteristics on regional radiative forcing in this paper. The experiments involve in refractive indices, single scattering aibedo, asymmetry factor and optical depth. An updated dataset of refractive indices representing East Asian dust and the one recommended by the World Meteorology Organization （WMO） are contrastively analyzed and used. A radiative transfer code for solar and thermal infrared radiation with detailed aerosol parameterization is employed. The strongest emphasis is on the refractive indices since other optical parameters strongly depend on it, and the authors found a strong sensitivity of radiative forcing on refractive indices. Studies show stronger scattering, weaker absorption and forward scattering of the East Asian dust particles at solar wavelengths, which leads to higher negative forcing, lower positive forcing and bigger net forcing at the top of the atmosphere （TOA） than that of the WMO dust model. It is also found that the TOA forcings resulting from these two dust models have opposite signs in certain regions, which implies the importance of accurate measurements of optical properties in the quantitative estimation of radiative forcing.展开更多
Al and F co-doped ZnO(ZnO:(Al,F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents.The structural,electrical and optical properties of the deposited films are...Al and F co-doped ZnO(ZnO:(Al,F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents.The structural,electrical and optical properties of the deposited films are sensitive to the F doping content.The X-ray analysis shows that the films are c-axis orientated along the(002) plane with the grain size ranging from 9 nm to 13 nm.Micrographs obtained by the scanning electron microscope(SEM) show a uniform surface.The best films obtained have a resistivity of 2.16×10-3Ω·cm,while the high optical transmission is 92.0% at the F content of 2.46 wt.%.展开更多
Zinc oxide （ZnO） thin films were deposited on sapphire （0001） substrates at room temperature by radiofrequency （RF） magnetron sputtering at oxygen gas contents of 0%, 25%, 50% and 75%, respectively. The influenc...Zinc oxide （ZnO） thin films were deposited on sapphire （0001） substrates at room temperature by radiofrequency （RF） magnetron sputtering at oxygen gas contents of 0%, 25%, 50% and 75%, respectively. The influence of oxygen gas content on the structural and optical properties of ZnO thin films was studied by a surface profile measuring system, X-ray diffraction analysis, atomic force microscopy, and UV spectro- photometry. It is found that the size of ZnO crystalline grains increases first and then decreases with the increase of oxygen gas content, and the maximum grain size locates at the 25% oxygen gas content. The crystalline quality and average optical transmittance （〉90%） in the visi- ble-light region of the ZnO film prepared at an oxygen gas content of 25% are better than those of ZnO films at the other contents. The obtained results can be attributed to the resputtefing by energetic oxygen anions in the growing process.展开更多
The direct radiative forcing （DRF） of sulfate aerosols depends highly on the atmospheric sulfate loading and the meteorology, both of which undergo strong regional and seasonal variations. Because the optical proper...The direct radiative forcing （DRF） of sulfate aerosols depends highly on the atmospheric sulfate loading and the meteorology, both of which undergo strong regional and seasonal variations. Because the optical properties of sulfate aerosols are also sensitive to atmospheric relative humidity, in this study we first examine the scheme for optical properties that considers hydroscopic growth. Next, we investigate the seasonal and regional distributions of sulfate DRF using the sulfate loading simulated from NCAR CAM-Chem together with the meteorology modeled from a spectral atmospheric general circulation model （AGCM） developed by LASG-IAP. The global annual-mean sulfate loading of 3.44 mg m-2 is calculated to yield the DRF of -1.03 and -0.57 W m-2 for clear-sky and all-sky conditions, respectively. However, much larger values occur on regional bases. For example, the maximum all-sky sulfate DRF over Europe, East Asia, and North America can be up to -4.0 W m-2. The strongest all-sky sulfate DRF occurs in the Northern Hemispheric July, with a hemispheric average of -1.26 W m-2. The study results also indicate that the regional DRF are strongly affected by cloud and relative humidity, which vary considerably among the regions during different seasons. This certainly raises the issue that the biases in model-sinmlated regional meteorology can introduce biases into the sulfate DRF. Hence, the model processes associated with atmospheric humidity and cloud physics should be modified in great depth to improve the simulations of the LASG-IAP AGCM and to reduce the uncertainty of sulfate direct effects on global and regional climate in these simulations.展开更多
Aerosol optical properties over Beijing and Xianghe under several typical weather conditions （clear sky, light haze, heavy pollution and dust storm） are derived from POLDER （POLarization and Directionality of the E...Aerosol optical properties over Beijing and Xianghe under several typical weather conditions （clear sky, light haze, heavy pollution and dust storm） are derived from POLDER （POLarization and Directionality of the Earth＇s Reflectances）/PARASOL （Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar） multi-directional, multi-spectral polarized signals using a more reliable retrieval algorithm as proposed in this paper. The results are compared with those of the operational retrieval algorithm of POLDER/PARASOL group and the ground-based AERONET （AErosol RObotic NETwork）/PHOTONS （PHOtometrie pour le Traitement Operational de Normalisation Satellitaire） measurements. It is shown that the aerosol optical parameters derived from the improved algorithm agree well with AERONET/PHOTONS measurement. The retrieval accuracies of aerosol optical thickness （AOT） and effective radius are 0.06 and 0.05 μm respectively, which are close to or better than the required accuracies （0.04 for AOT and 0.1 μm for effective radius） for estimating aerosol direct forcing.展开更多
The optical properties of aerosol as well as their impacting factors were investigated at a suburb site in Nanjing during autumn from 14 to 28 November 2012. More severe pollution was found together with lower visibil...The optical properties of aerosol as well as their impacting factors were investigated at a suburb site in Nanjing during autumn from 14 to 28 November 2012. More severe pollution was found together with lower visibility. The average scattering and absorption coefficients（B sca and B abs） were 375.7 ± 209.5 and 41.6 ± 18.7 Mm^（-1）, respectively. Higher ？ngstr？m absorption and scattering exponents were attributed to the presence of more aged aerosol with smaller particles. Relative humidity（RH） was a key factor affecting aerosol extinction. High RH resulted in the impairment of visibility, with hygroscopic growth being independent of the dry extinction coefficient. The hygroscopic growth factor was 1.8 ± 1.2 with RH from 19% to 85%.Light absorption was enhanced by organic carbon（OC）, elemental carbon（EC） and EC coatings,with contributions of 26%, 44% and 75%（532 nm）, respectively. The B sca and B abs increased with increasing N_（100）（number concentration of PM_（2.5）with diameter above 100 nm）, PM_1 surface concentration and PM_（2.5）mass concentration with good correlation.展开更多
Nanomaterials possess intriguing optical properties that depend sensitively on size, shape, and material content of the structures. Controlling such structural characteristics of the nanostructures allows the tailorin...Nanomaterials possess intriguing optical properties that depend sensitively on size, shape, and material content of the structures. Controlling such structural characteristics of the nanostructures allows the tailoring of their physical and chemical properties, e.g. optical, electronic, and catalytic, to achieve what is desired lot specific applications of interest. This review will cover the development of various shapes for silver and gold nanomaterials with emphasis on their relation to optical properties. Examples of various modern synthetic methods and characterization techniques are highlighted. The influence of the metal nanomaterial＇s shape and optical absorption on surface enhanced Raman scattering （SERS） and a final note on new emerging applications of metal nanostructures are also discussed.展开更多
An algorithm to retrieve aerosol optical properties using multi-angular,multi-spectral,and polarized data without a priori knowledge of the land surface was developed.In the algorithm,the surface polarized reflectance...An algorithm to retrieve aerosol optical properties using multi-angular,multi-spectral,and polarized data without a priori knowledge of the land surface was developed.In the algorithm,the surface polarized reflectance was estimated by eliminating the atmospheric scattering from measured polarized reflectance at 1640 nm.A lookup table （LUT） and an iterative method were adopted in the algorithm to retrieve the aerosol optical thickness （AOT,at 665 nm） and the （A）ngstr（o）m exponent （computed between the AOTs at 665 and 865 nm）.Experiments were performed in Tianjin to verify the algorithm.Data were provided by a newly developed airborne instrument,the Advanced Atmosphere Multi-angle Polarization Radiometer （AMPR）.The AMPR measurements over the target field agreed well with the nearby ground-based sun photometer.An algorithm based on Research Scanning Polarimeter （RSP） measurements was introduced to validate the observational measurements along a flight path over Tianjin.The retrievals were consistent between the two algorithms.The AMPR algorithm shows potential in retrieving aerosol optical properties over a vegetation surface.展开更多
We tested and modified the quasi-analytical algorithm （QAA） using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coef...We tested and modified the quasi-analytical algorithm （QAA） using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coefficients of typical coastal waters. The average percentage difference （APD） is in a range of 13.9%-38.5% for the total absorption coefficient （13.9% at 440 nm）, and differences in particle backscattering coefficient bbp（2） are less than 50% （in the case of the updated QAA）. To obtain improved results, we modified the QAA by adjusting the empirical relationships. The modified algorithm is then applied to the field data to test its performance. The APDs were 44.7%-46.6% for bbp（λ） and 9.9%-32.8% （9.9% at 555 nm） for the total absorption coefficient. This indicates that the modified QAA derives better results. We also used the modified model to derive phytoplankton pigment absorption （aph） and detritus and CDOM absorption （aug） coefficients. The APDs for aph and a dg at 440 nm are 37.1% and 19.8%. In this paper, we discuss error sources using the measured dataset. More independent field data can improve this algorithm and derive better results.展开更多
To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The ...To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The concentrations and chemical compositions of PM2.5,aerosol optical properties and meteorological parameters were measured.The mean value of PM2.5 increased from less than 35(excellent)to 35-75μg/m^3(good)and then to greater than 75μg/m^3(pollution),corresponding to mean PM2.5 values of 24.9,51.2,and 93.3μg/m^3,respectively.The aerosol scattering hygroscopic growth factor(f(RH=80%))values were 2.0,2.12,and 2.18 for the excellent,good,and pollution levels,respectively.The atmospheric extinction coefficient(σext)and the absorption coefficient of aerosols(σap)increased,and the single scattering albedo(SSA)decreased from the excellent to the pollution levels.For different air mass sources,under excellent and good levels,the land air mass from northern Heshan had lower f(RH)andσsp values.In addition,the mixed aerosol from the sea and coastal cities had lower f(RH)and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.展开更多
基金supported by the CAS Strategic Priority Research Program(No.XDB0760102),the Ministry of Science and Technology of China(No.2022YFF0802501)the Major Science and Technology Infrastructure Maintenance and Transformation Project of the Chinese Academy of Sciences,Shanghai Science and Technology Innovation Action Plan-Phospherus Project(No.23YF1426200)the National Key Research and Development Program of China(No.2024YFE0212200).
文摘In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.
基金financially supported by the National Natural Science Foundation of China(Grant No.11872344)the Innovatory Development Foundation of the China Academy of Engineering Physics(Grant No.CX20210026).
文摘Over the past several decades,much research effort has been dedicated to the study of optical windows,with two primary themes emerging as key focuses.The first of these centers on investigating the optical properties of typical transparent single crystals under shock or ramp compression,which helps in the selection of appropriate optical windows for high-pressure experiments.The second involves the exploration of novel optical windows,particularly transparent polycrystalline ceramics,which not only match the shock impedance of the samples,but also preserve transparency under dynamic compression.In this study,we first integrate existing research on the evolution of optical properties in transparent single crystals and polycrystalline ceramics subjected to shock or ramp loading,proposing a mechanism that links mesoscopic damage to macroscopic optical transparency.Subsequently,through a systematic integration of experiments and computational analyses on polycrystalline transparent ceramics,we demonstrate that shock transparency can be enhanced by optimizing grain size and that shock impedance can be designed via compositional tuning.Notably,our results reveal that nano-grained MgAl_(2)O_(4) ceramics exhibit outstanding optical transparency under high shock pressures,highlighting a promising strategy for designing optical windows that retain transparency under extreme dynamic loading conditions.
文摘Density functional theory(DFT)studies were performed on the lattice parameters,electronic band structure,and optical constants under pressure up to 20 GPa in order to obtain insight into the electronic and optical properties of LiZnAs.The calculated results show LiZnAs is a semiconductor with a direct gap of 0.86 eV,which is smaller than the experimental value 1.1 eV.It also indicates that the structural parameters such as lattice parameters and cell volume show inverse relation to the pressure and shows smooth decreasing behavior from 0 to 20 GPa.Meanwhile,the pressure dependence of the electronic band structure,density of states and partial density of states of LiZnAs up to 20 GPa were presented.And we found that the band gap increased with the pressure.Moreover,the evolution of the dielectric function,absorption coefficient a(w),reflectivity R(w),the refractive index n(w),and the extinction coefficient k(w)of LiZnAs under pressure were presented.According to our work,we found that the optical properties of LiZnAs undergo a blue shift with increasing pressure.These results suggest technological applications of such materials in extreme environments.
基金Project (07C26214301746) supported by Innovation Foundation of Ministry of Science and Technology, ChinaProject (2010GXNSFB013008) supported by Guangxi Natural Science Foundation, ChinaProject (2009bsxt001) supported by the Graduate Degree Thesis Innovation Foundation of Central South University, China
文摘Pyrochlore structure La2Sn2O7：Eu3＋ microcrystals with uniform octahedron shape were successfully synthesized via a hydrothermal route at 180 °C for 36 h. The crystal structure, particle size, morphologies, and optical properties of the as-synthesized products were investigated by XRD, TEM, SEM, EDS, FT-IR, Raman spectroscopy and PL. The effects of pH of precursor solution, precursor concentration, reaction temperature, and time were investigated. The results reveal that pH of the precursor solution not only plays an important role in determining the phase of the as-synthesized products, but also has a significant influence on the morphologies of the samples. High-quality and uniform octahedrons with an average size of about 700 nm could be easily obtained at the pH value of 12. The possible formation mechanism of octahedral-like La2Sn2O7：Eu3＋ microcrystals was briefly proposed. The photoluminescence spectra show that La2Sn2O7：Eu3＋ micro-octahedra display stronger emission in the range of 582-592 nm compared with the samples with other shapes.
基金Project(21101013) supported by the National Natural Science Foundation of ChinaProjects(FRF-SD-13-002B,FRF-BR-09-004A) supported by the Fundamental Research Funds for the Central Universities,China
文摘Monodisperse zinc phosphate microspheres were synthesized by a facile solvothermal method in the presence of oleic acid.X-ray powder diffraction（XRD）,Fourier transform infrared spectrum（FT-IR）,emission scanning electron microscopy（SEM）,and energy dispersive X-ray spectrum（EDX） were used to characterize the microstructures and morphologies of the as-obtained zinc phosphate samples.The experimental results indicate that the zinc phosphate products are well crystallized,and the morphologies of the samples can be easily controlled by the elaborate choice of oleic acid addition and the content of NaOH.Furthermore,self-activated luminescent properties of the products are observed.The as-obtained samples show an intense blue emission under a long-wavelength UV light excitation of 400 nm.The possible luminescent mechanism may be ascribed to the carbon-related surface impurities or defects.
基金supported by the National Natural Science Foundation of China(Nos.22176112 and 42307134)the Natural Science Foundation of Shandong Province(No.ZR2021MD028)the Natural Science Foundation of Qingdao(No.23–2-1–74-zyyd-jch).
文摘The optical absorption of large molecular compounds HULIS(humic-like substances)can significantly impact the aerosol light absorption and radiative forcing,influencing cloud condensation nuclei formation and thus the climate and atmospheric environment.This study collected aerosol(PM_(2.5))samples from the summit of Mount Tai in North China to investigate the concentration,molecular composition,and optical properties of HULIS.The average concentration of HULIS in the PM_(2.5) in this study was 1.26±0.54μg/m^(3),comprising for 56%of the water-soluble organic carbon(WSOC),with levels lower than urban areas but higher than other mountainous regions.Mass spectrometry revealed that CHO and CHON components,with high aromaticity and phenolic groups,are major contributors to absorption and fluorescence.These results indicate that HULIS is mainly composed of lignin and proteins/amino sugars,derived from combustion and secondary formation,and possesses a high light absorption capacity(withMAE365(mass absorption efficiency)and AAE(A˚ngstrom exponent)indices of 0.62m^(2)/g and 4.99,respectively).Parallel factor analysis identified three fluorescence components of HULIS,with proportions of 60.8%for less oxygen humic-like substances,21.0%for high oxygen humic-like substances,and 18.2%for protein-like substances.Our study highlights the significance of the light-absorbing capacity and secondary formation of HULIS at Mount Tai,laying the groundwork for investigation into the climate effects,formation mechanisms,and sources of HULIS generation.
文摘ZnS ∶Cu nanoparticles were prepared by using microemulsion method at room temperature. The size of the particles is 2-8 nm by transmission electron microscopy (TEM) and dynamic light scattering (DLS) technique. X-ray diffraction analysis shows that the particles are cubic crystal structure, the same structure as the bulk ZnS materials. Ultraviolet absorption demonstrates an increased bandgap due to quantum confinement effect. Photoluminescence spectrum shows there is a single green emission band at 482 nm.
文摘ZnO films grown by metal organic chemical vapor deposition at atmospheric pressure are annealed at 850℃ ,with the film surfaces exposed to air or covered by a sapphire wafer. The optical properties of the as-grown and the annealed samples are studied by photoluminescence （PL） spectroscopy. It is found that the air-exposure annealing effectively removes the hydrogen impurities from the ZnO films but greatly increases the deep-level emission. In the surface-covered annealed sample, an elimination of the hydrogen impurities is also observed, and the deep-level emission disappears completely. The free exciton emission is significantly enhanced in the ZnO film after surface-covered annealing.
基金supported by the National Basic Research Program(No.2007CB407303)National Natural Science Foundation of China(No.40675073)the 863 Program (No.2006AA06A303)
文摘Aerosol observational data at 8 ground-based observation sites in the Chinese Sun Hazemeter Network （CSHNET） were analyzed to characterize the optical properties of aerosol particles during the strong dust storm of 16-21 April 2005. The observational aerosol optical depth （AOD） increased significantly during this dust storm at sites in Beijing city （86%）, Beijing forest （84%）, Xianghe （13%）, Shapotou （27%）, Shenyang （47%）, Shanghai （23%）, and Jiaozhou Bay （24%）. The API （air pollution index） in Beijing and Tianjin also had a similar rise during the dust storm, while the Angstrhm exponent （a） declined evidently at sites in Beijing city （21%）, Beijing forest （39%）, Xianghe （19%）, Ordos （77%）, Shapotou （50%）, Shanghai （12%）, and Jiaozhou Bay （21%）, respectively. Furthermore, The observational AOD and a demonstrated contrary trends during M1 storm stages （pre-dust storm, dust storm, and post-dust storm）, with the AOD indicating an obvious ＂Valley Peak-Valley＂ pattern of variation, while a demonstrated a ＂Peak-Valley- Peak＂ pattern. In addition, the dust module in a regional climate model （RegCM3） simulated the dust storm occurrence and track accurately and RegCM3 was able to basically simulate the trends in AOD. The simulation results for the North China stations were the best, and the simulation for dust-source stations was on the high side, while the simulation was on the low side for coastal sites.
基金supported by grants from the National Key Project of Basic Research (2006CB403702 and 2006CB403701)the CAMS Basis Research Project and National Natural Science Foundation of China under Grant No. 40405001
文摘The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China, acquired through a CE318 sunphotometer of the ground-based Aerosol Robotic Network （AERONET）, are analyzed. The seasonal variations in the aerosol optical properties are examined. The effect of meteorological elements （pressure, temperature, water vapor pressure, relative humidity and wind speed） on the aerosol optical properties is also studied. Then, the sources and optical properties under two different cases, a dust event and a pollution event, are compared. The results show that the high aerosol optical depth （AOD） found in Yulin was mostly attributed to the occurrence of dust events in spring from the Mu Us desert and deserts of West China and Mongolia, as well as the impacts of anthropogenic pollutant particles from the middle part of China in the other seasons. The seasonal variation and the probability distribution of the radiative forcing and the radiative forcing efficiency at the surface and the top of the atmosphere are analyzed and regressed using the linear and Gaussian regression methods.
文摘There are large uncertainties in the quantitative assessment of radiative effects due to atmospheric dust aerosol. The optical properties contribute much to those uncertainties. The authors perform several sensitivity experiments to estimate the impacts of optical characteristics on regional radiative forcing in this paper. The experiments involve in refractive indices, single scattering aibedo, asymmetry factor and optical depth. An updated dataset of refractive indices representing East Asian dust and the one recommended by the World Meteorology Organization （WMO） are contrastively analyzed and used. A radiative transfer code for solar and thermal infrared radiation with detailed aerosol parameterization is employed. The strongest emphasis is on the refractive indices since other optical parameters strongly depend on it, and the authors found a strong sensitivity of radiative forcing on refractive indices. Studies show stronger scattering, weaker absorption and forward scattering of the East Asian dust particles at solar wavelengths, which leads to higher negative forcing, lower positive forcing and bigger net forcing at the top of the atmosphere （TOA） than that of the WMO dust model. It is also found that the TOA forcings resulting from these two dust models have opposite signs in certain regions, which implies the importance of accurate measurements of optical properties in the quantitative estimation of radiative forcing.
文摘Al and F co-doped ZnO(ZnO:(Al,F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents.The structural,electrical and optical properties of the deposited films are sensitive to the F doping content.The X-ray analysis shows that the films are c-axis orientated along the(002) plane with the grain size ranging from 9 nm to 13 nm.Micrographs obtained by the scanning electron microscope(SEM) show a uniform surface.The best films obtained have a resistivity of 2.16×10-3Ω·cm,while the high optical transmission is 92.0% at the F content of 2.46 wt.%.
基金supported by the National Natural Science Foundation of China (Nos. 60876055 and11074063)the Natural Science foundation of Hebei Province,China (Nos. E2008000620 and E2009000207)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20091301110002)the Key Basic Research Program of Hebei Provincial Applied Basic Research Plan (No. 10963525D)
文摘Zinc oxide （ZnO） thin films were deposited on sapphire （0001） substrates at room temperature by radiofrequency （RF） magnetron sputtering at oxygen gas contents of 0%, 25%, 50% and 75%, respectively. The influence of oxygen gas content on the structural and optical properties of ZnO thin films was studied by a surface profile measuring system, X-ray diffraction analysis, atomic force microscopy, and UV spectro- photometry. It is found that the size of ZnO crystalline grains increases first and then decreases with the increase of oxygen gas content, and the maximum grain size locates at the 25% oxygen gas content. The crystalline quality and average optical transmittance （〉90%） in the visi- ble-light region of the ZnO film prepared at an oxygen gas content of 25% are better than those of ZnO films at the other contents. The obtained results can be attributed to the resputtefing by energetic oxygen anions in the growing process.
基金supported jointly by the grant from National Basic Research Program of China(Grant No.2012CB955303)and from the Office of Biological and Environmental Sciences,US Department of Energy
文摘The direct radiative forcing （DRF） of sulfate aerosols depends highly on the atmospheric sulfate loading and the meteorology, both of which undergo strong regional and seasonal variations. Because the optical properties of sulfate aerosols are also sensitive to atmospheric relative humidity, in this study we first examine the scheme for optical properties that considers hydroscopic growth. Next, we investigate the seasonal and regional distributions of sulfate DRF using the sulfate loading simulated from NCAR CAM-Chem together with the meteorology modeled from a spectral atmospheric general circulation model （AGCM） developed by LASG-IAP. The global annual-mean sulfate loading of 3.44 mg m-2 is calculated to yield the DRF of -1.03 and -0.57 W m-2 for clear-sky and all-sky conditions, respectively. However, much larger values occur on regional bases. For example, the maximum all-sky sulfate DRF over Europe, East Asia, and North America can be up to -4.0 W m-2. The strongest all-sky sulfate DRF occurs in the Northern Hemispheric July, with a hemispheric average of -1.26 W m-2. The study results also indicate that the regional DRF are strongly affected by cloud and relative humidity, which vary considerably among the regions during different seasons. This certainly raises the issue that the biases in model-sinmlated regional meteorology can introduce biases into the sulfate DRF. Hence, the model processes associated with atmospheric humidity and cloud physics should be modified in great depth to improve the simulations of the LASG-IAP AGCM and to reduce the uncertainty of sulfate direct effects on global and regional climate in these simulations.
基金supported by National Natural Science Foundation of China(Grant No.40805010)the 973 Program of China under Grant No.2006CB403702
文摘Aerosol optical properties over Beijing and Xianghe under several typical weather conditions （clear sky, light haze, heavy pollution and dust storm） are derived from POLDER （POLarization and Directionality of the Earth＇s Reflectances）/PARASOL （Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar） multi-directional, multi-spectral polarized signals using a more reliable retrieval algorithm as proposed in this paper. The results are compared with those of the operational retrieval algorithm of POLDER/PARASOL group and the ground-based AERONET （AErosol RObotic NETwork）/PHOTONS （PHOtometrie pour le Traitement Operational de Normalisation Satellitaire） measurements. It is shown that the aerosol optical parameters derived from the improved algorithm agree well with AERONET/PHOTONS measurement. The retrieval accuracies of aerosol optical thickness （AOT） and effective radius are 0.06 and 0.05 μm respectively, which are close to or better than the required accuracies （0.04 for AOT and 0.1 μm for effective radius） for estimating aerosol direct forcing.
基金supported by the Commonwealth Program of Environment Protection Department of China (No.201409027-05)the National Natural Science Foundation of China (No.21577065)+2 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Postgraduate Innovation Foundation of Jiangsu Province (No.CXZZ11_0611)the International ST Cooperation Program of China (ISTCP) (No.2014DFA90780)
文摘The optical properties of aerosol as well as their impacting factors were investigated at a suburb site in Nanjing during autumn from 14 to 28 November 2012. More severe pollution was found together with lower visibility. The average scattering and absorption coefficients（B sca and B abs） were 375.7 ± 209.5 and 41.6 ± 18.7 Mm^（-1）, respectively. Higher ？ngstr？m absorption and scattering exponents were attributed to the presence of more aged aerosol with smaller particles. Relative humidity（RH） was a key factor affecting aerosol extinction. High RH resulted in the impairment of visibility, with hygroscopic growth being independent of the dry extinction coefficient. The hygroscopic growth factor was 1.8 ± 1.2 with RH from 19% to 85%.Light absorption was enhanced by organic carbon（OC）, elemental carbon（EC） and EC coatings,with contributions of 26%, 44% and 75%（532 nm）, respectively. The B sca and B abs increased with increasing N_（100）（number concentration of PM_（2.5）with diameter above 100 nm）, PM_1 surface concentration and PM_（2.5）mass concentration with good correlation.
基金the National Science Foundation,NASA-UARC,US Armythe Lawrence Scholar Program(formerly known as Student Employee Graduate Research Fellowship).
文摘Nanomaterials possess intriguing optical properties that depend sensitively on size, shape, and material content of the structures. Controlling such structural characteristics of the nanostructures allows the tailoring of their physical and chemical properties, e.g. optical, electronic, and catalytic, to achieve what is desired lot specific applications of interest. This review will cover the development of various shapes for silver and gold nanomaterials with emphasis on their relation to optical properties. Examples of various modern synthetic methods and characterization techniques are highlighted. The influence of the metal nanomaterial＇s shape and optical absorption on surface enhanced Raman scattering （SERS） and a final note on new emerging applications of metal nanostructures are also discussed.
基金supported by the Chinese Airborne Remote Sensing System, the Major National Science and Technology Infrastructure Construction Projectsthe Key Programs of the Chinese Academy of Sciences (Grant No. KGFZD125-13-006)
文摘An algorithm to retrieve aerosol optical properties using multi-angular,multi-spectral,and polarized data without a priori knowledge of the land surface was developed.In the algorithm,the surface polarized reflectance was estimated by eliminating the atmospheric scattering from measured polarized reflectance at 1640 nm.A lookup table （LUT） and an iterative method were adopted in the algorithm to retrieve the aerosol optical thickness （AOT,at 665 nm） and the （A）ngstr（o）m exponent （computed between the AOTs at 665 and 865 nm）.Experiments were performed in Tianjin to verify the algorithm.Data were provided by a newly developed airborne instrument,the Advanced Atmosphere Multi-angle Polarization Radiometer （AMPR）.The AMPR measurements over the target field agreed well with the nearby ground-based sun photometer.An algorithm based on Research Scanning Polarimeter （RSP） measurements was introduced to validate the observational measurements along a flight path over Tianjin.The retrievals were consistent between the two algorithms.The AMPR algorithm shows potential in retrieving aerosol optical properties over a vegetation surface.
基金Supported by the National Natural Science Foundation of China (Nos.40706060,60802089)the National High Technology Research and Development Program of China (863 Program) (No.2007AA092102)the Dragon Project (No.5292)
文摘We tested and modified the quasi-analytical algorithm （QAA） using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coefficients of typical coastal waters. The average percentage difference （APD） is in a range of 13.9%-38.5% for the total absorption coefficient （13.9% at 440 nm）, and differences in particle backscattering coefficient bbp（2） are less than 50% （in the case of the updated QAA）. To obtain improved results, we modified the QAA by adjusting the empirical relationships. The modified algorithm is then applied to the field data to test its performance. The APDs were 44.7%-46.6% for bbp（λ） and 9.9%-32.8% （9.9% at 555 nm） for the total absorption coefficient. This indicates that the modified QAA derives better results. We also used the modified model to derive phytoplankton pigment absorption （aph） and detritus and CDOM absorption （aug） coefficients. The APDs for aph and a dg at 440 nm are 37.1% and 19.8%. In this paper, we discuss error sources using the measured dataset. More independent field data can improve this algorithm and derive better results.
基金supported by the National Natural Science Foundation of China(No.91544221)the People’s Republic of China Science and Technology Department(No.2016YFC0202004)
文摘To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The concentrations and chemical compositions of PM2.5,aerosol optical properties and meteorological parameters were measured.The mean value of PM2.5 increased from less than 35(excellent)to 35-75μg/m^3(good)and then to greater than 75μg/m^3(pollution),corresponding to mean PM2.5 values of 24.9,51.2,and 93.3μg/m^3,respectively.The aerosol scattering hygroscopic growth factor(f(RH=80%))values were 2.0,2.12,and 2.18 for the excellent,good,and pollution levels,respectively.The atmospheric extinction coefficient(σext)and the absorption coefficient of aerosols(σap)increased,and the single scattering albedo(SSA)decreased from the excellent to the pollution levels.For different air mass sources,under excellent and good levels,the land air mass from northern Heshan had lower f(RH)andσsp values.In addition,the mixed aerosol from the sea and coastal cities had lower f(RH)and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.
