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Water-soluble brown carbon in atmospheric aerosols from the resource-dependent cities:optical properties,chemical compositions and sources

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Journal of Environmental Sciences 2024年第4期138卷 74-87页

作者： Haoji Wang Yue Su Yangzheng Liu Fei Xie Xingjun Zhou Ruihong Yu Changwei Lü Jiang He School of Ecology and Environment Inner Mongolia UniversityHohhot 010021China Institute of Environmental Geology Inner Mongolia UniversityHohhot 010021China Environmental Monitoring Center of Inner Mongolia Hohhot 010011China

As a vital type of light-absorbing aerosol,brown carbon(BrC)presents inherent associations with atmospheric photochemistry and climate change.However,the understanding of the chemical and optical properties of BrC is limited,especially in some resource-dependent cities with long heating periods in northwest China.This study showed that the annual average abundances of Water-soluble BrC(WS-BrC)were 9.33±7.42 and 8.69±6.29μg/m^(3)in Baotou and Wuhai and the concentrations,absorption coefficient(Abs_(365)),and mass absorption efficiency(MAE365)of WS-BrC presented significant seasonal patterns,with high values in the heating season and low values in the non-heating season;while showing opposite seasonal trends for the Absorption Angstr?m exponent(AAE_(300-400)).Comparatively,the levels of WS-BrC in developing regions(such as cities in Asia)were higher than those in developed regions(such as cities in Europe and Australia),indicating the significant differences in energy consumption in these regions.By combining fluorescence excitation-emission matrix(EEM)spectra with the parallel factor(PARAFAC)model,humic-like(C1 and C2)and proteinlike(C3)substances were identified,and accounted for 61.40%±4.66%and 38.6%±3.78%at Baotou,and 60.33%±6.29%and 39.67%±4.17%at Wuhai,respectively.The results of source apportionment suggested that the potential source regions of WS-BrC varied in heating vs.non-heating seasons and that the properties of WS-BrC significantly depended on primary emissions(e.g.,combustion emissions)and secondary formation.

关键词： Water-soluble brown carbon Atmospheric aerosols optical properties PARAFAC Source apportionment

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Incorporation sodium ions into monodisperse lead-free double perovskite Cs_(2)AgBiCl_(6) nanocrystals to improve optical properties

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Chinese Chemical Letters 2024年第3期35卷 549-553页

作者： Song Wang Ying Xie Wenchao Jiang Binghang Liu Keying Shi Kai Pan Key Laboratory of Functional Inorganic Material Chemistry Ministry of EducationHeilongjiang UniversityHarbin 150080China School of Materials Science and Engineering Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and ApplicationsChangzhou UniversityChangzhou 213164China State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China

Lead-free double perovskite nanocrystals(NCs)have emerged as a promising candidate in the optical field,owing to their non-toxic,good moist heat and chemical stability.However,their poor optical properties limited their application.To improve the optical properties of lead-free double perovskite NCs,metal ion doping or alloying had been suggested as a promising strategy.Here,we prepared monodisperse,uniformly sized,cubic morphology of Cs_(2)AgBiCl_(6)NCs with different Na^(+)incorporation amounts via a simple hot-injection method.The Na^(+)incorporation broke the parity-forbidden transition by reducing the inversion symmetry of the electron wave function at the Ag site,which changed the parity of the self-trapped exciton wave function and thus allowed radiative recombination.As a result,the photoluminescence quantum yield(PLQY)of Na^(+)-alloyed Cs_(2)AgBiCl_(6)NCs(12.1%)was higher than that of Cs_(2)AgBiCl_(6)NCs(2.4%),and the exciton lifetime of Na^(+)-alloyed Cs_(2)AgBiCl_(6)NCs increased to 36.98 ns from 17.58 ns for Cs_(2)AgBiCl_(6)NCs.By adjusting the amount of Na^(+)incorporation,the band gap of Cs_(2)AgBiCl_(6)NCs can be significantly tuned from~2.90 eV to~3.50 eV.Furthermore,the temperature-dependent photoluminescence spectra indicated that the Na^(+)-alloyed Cs_(2)AgBiCl_(6)NCs possessed higher longitudinal optical phonon energy and exciton binding energy compared to Cs_(2)AgBiCl_(6)NCs.This suggested that there were strong exciton-phonon interactions during exciton recombination,a reduced probability of non-radiative processes,and excellent thermal stability.It offers a promising strategy for improving the optical properties of lead-free double perovskite NCs,and have the potential to replace traditional lead halide perovskite NCs in future optoelectronic applications.

关键词： Nanocrystals Alloy Double perovskites optical properties Exciton binding energy

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GGA + U Study of the optical properties of α-BeH2

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Open Journal of Applied Sciences 2024年第6期14卷 1507-1511页

作者： Uko Ofe Department of Pure and Applied Physics Veritas University Abuja Nigeria

The optical properties of α-BeH2 in an Orthorhombic crystal structure with the space group (Ibam) are investigated. We have calculated the optical properties including dielelectric function, refractive index and extinction coefficient, using density functional approach. A theoretical explanation of the relationship between the dielectric function and other optical constants has been provided. Furthermore, the real and imaginary components of the dielectric function have been examined. The effects of the exchange-correlation potentials (GGA and GGA + U) applied on this compound’s absorption peaks and edges have also been investigated. It was found that using the GGA + U approximation caused the conduction band to shift, which in turn caused the initial absorption peak to shift.

关键词： Dielectric Function optical properties GGA and GGA + U Approximations

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optical properties of two-dimensional perovskites

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Frontiers of physics 2023年第3期18卷 1-26页

作者： Junchao Hu Xinglin Wen Dehui Li School of optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

The optical properties of two-dimensional(2D)perovskites recently receive numerous research focus thanks to the strong quantum and dielectric confinement effects.In addition to the strong excitonic effect at room temperature,2D perovskites also have appealing features that their optical properties can be flexibly tuned by alternating organic or inorganic layers.Particularly,2D chiral perovskites and 2D perovskites based heterostructures are emerging as new platforms to extend their functionalities.To optimize performance of 2D perovskites-based optoelectronic devices,it is critical to understand the fundamentals and explore the strategies to engineer their optical properties.This review begins with an introduction to the excitons and self-trapped excitons of 2D perovskites.Subsequently,inorganic/organic layer effects on optical properties and 2D perovskites based heterostructures are discussed.We also discussed the nonlinear optical properties of 2D perovskite.We are looking forward to that this review can stimulate more efforts to understand and optimize the optical properties of 2D perovskites.

关键词： optical properties two-dimensional perovskite heterostructures self-trapped excitons

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optical properties of Al_(x)Ga_(1-x)As/GaAs Woods-Saxon quantum well in the presence of hydrostatic pressure and applied electric field

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Communications in Theoretical Physics 2022年第6期74卷 143-151页

作者： Zhi-Hai Zhang Yi-Sheng Shi Jian-Hui Yuan School of Physics and Electronics Yancheng Teachers UniversityYancheng 224002China Intelligent photoelectric device and measurement engineering research center Yancheng Teachers UniversityYancheng 224002China The Laboratory of Biomedical Photonics and Engineering Guangxi Medical UniversityNanning 530021China

The third harmonic generation(THG),linear and nonlinear optical absorption coefficients(OACs),and refractive index changes(RICs)are investigated in a Woods-Saxon quantum well(QW)modulated by the hydrostatic pressure and applied electric field.The effect of non-uniform aluminum doping(position-dependent effective mass(PDEM))on the mass of the system is discussed,and further to explore the influence of PDEM on the nonlinear THG,OACs,and RICs of the Woods-Saxon QW.These nonlinear optical properties above are obtained using the compact-density matrix formalism.The electron states in a Woods-Saxon QW under the constant effective mass(CEM)and PDEM are calculated by solving the Schr?dinger equation via the finite difference technique.The contributions from competing effects of the hydrostatic pressure and applied electric field to the nonlinear optical properties with CEM and PDEM are reported,as well as the comparison with each other.The observations reveal that the regulation of external fields and the influence of PDEM play an important role in the photoelectric properties of QW.

关键词： optical properties position dependent effective mass hydrostatic pressure electric field

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Water-soluble matter in PM_(2.5)in a coastal city over China:Chemical components,optical properties,and source analysis

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Journal of Environmental Sciences 2022年第4期34卷 21-36页

作者： Yanan Zhan Narcisse T.Tsona Jianlong Li Qingcai Chen Lin Du Environment Research Institute Shandong UniversityQingdao 266237China School of Environmental Science and Engineering Shaanxi University of Science and TechnologyXi’an 710021China

Although marine and terrestrial emissions simultaneously affect the formation of atmospheric fine particles in coastal areas,knowledge on the optical properties and sources of water-soluble matter in these areas is still scarce.In this work,taking Qingdao,China as a typical coastal location,the chemical composition of PM_(2.5)duringwinter 2019was analyzed.Excitation-emission matrix fluorescence spectroscopy was combined with parallel factor analysis model to explain the components of water-soluble atmospheric chromophores of PM_(2.5).Our analysis indicated that NO_(3)^(-),NH_(4)^(+)and SO_(4)^(2-)ions accounted for 86.80%of the total ion mass,dominated by NO_(3)^(-).The ratio of[NO_(3)^(-)]/[SO_(4)^(2-)]was up to 2.42±0.84,suggesting thatmobile sources play an important role in local pollutants emission.The result of positive correlation between Abs_(365)with K^(+)suggests that biomass burning is an important source of water-soluble organic compounds(WSOC).Six types of fluorophores(C1-C6),all humic-like substances,were identified in WSOC.Humification index,biological index and fluorescence index in winter were 1.66±0.34,0.51±0.44 and 1.09±0.78,respectively,indicating that WSOC in Qingdao were mainly terrestrial organic matters.Overall,although the study area is close to the ocean,the contribution of terrestrial sources to PM_(2.5),especially vehicle exhaust and coal combustion,is still much higher than that of marine sources.Our study provides a more comprehensive understanding of chemical and optical properties of WSOC based on PM_(2.5)in coastal areas,and may provide ground for improving local air quality.

关键词： Excitation-emission matrix spectroscopy Chemical components optical properties PM_(2.5) Coastal city

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Polarity,intramolecular charge transfer,and hydrogen bond comediated solvent effects on the optical properties of graphene quantum dots

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Nano Research 2023年第1期16卷 45-52页

作者： Yalei Hu Christof Neumann Lena Scholtz Andrey Turchanin Ute Resch-Genger Siegfried Eigler Institute of Chemistry and Biochemistry Freie Universität BerlinTakustraße 314195 BerlinGermany Institute of Physical Chemistry and Abbe Center of Photonics Friedrich Schiller University JenaLessingstraße 1007743 JenaGermany Federal Institute for Materials Research and Testing(BAM) Division BiophotonicsRichard Willstätter Straße 1112489 BerlinGermany

Graphene quantum dots(GQDs)have attracted increasing attention due to their favorable optical properties and have been widely used,e.g.,in the biomedical field.However,the properties related to the chemical structure of GQDs,resulting in solventdependent optical properties,still remain unclear.Herein,we present the synthesis of long-wavelength emitting GQDs with a size of about 3.6 nm via a solvothermal method using oxo-functionalized graphene(oxo-G)and p-phenylenediamine as precursors and their structural and surface chemical analysis by transmission electron and atomic force microscopy(TEM;AFM)as well as Fourier-transform infrared,Raman,and X-ray photoelectron spectroscopy(FTIR;Raman;XPS).Subsequently,the influence of solvent polarity and proticity on the optical properties of the as-prepared GQDs bearing–OH,–NH_(2),–COOH and pyridine surface groups was investigated.Based on the results of the absorption and fluorescence(FL)studies,a possible luminescence mechanism is proposed.The observed solvent-induced changes in the spectral position of the FL maximum,FL quantum yield,and FL decay kinetics in protic and aprotic solvents of low and high polarity are ascribed to a combination of polarity effects,intramolecular charge transfer(ICT)processes,and hydrogen bonding.Moreover,the potential of GQDs for the optical sensing of trace amount of water was assessed.The results of our systematic spectroscopic study will promote the rational design of GQDs and shed more light on the FL mechanism of carbon-based fluorescent nanomaterials.

关键词： graphene quantum dots(GQDs) polarity intramolecular charge transfer(ICT) hydrogen bond optical properties

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Effect of warpage on the electronic structure and optical properties of bilayer germanene

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Journal of Semiconductors 2022年第12期43卷 39-45页

作者： Qihang Xiong Weifu Cen Xingtong Wu Cong Chen College of Chemical Engineering Guizhou Minzu UniversityGuiyang 550025China College of Materials Science and Engineering Guizhou Minzu UniversityGuiyang 550025China College of Mechanical and Electrical Engineering Guizhou Minzu UniversityGuiyang 550025China

The electronic structure and optical properties of bilayer germanene under different warpages are studied by the first-principles method of density functional theory.The effects of warpages on the electronic structure and optical properties of bilayer germanene are analyzed.The results of the electronic structure study show that the bottom of the conduction band of bilayer germanene moves to the lower energy direction with the increase of warpages at the K point,and the top of the valence band stays constant at the K point,and so the band gap decreases with the increase of warpage.When the warpage is 0.075 nm,the top of the valence band of bilayer germanene changes from K point to G point,and the bilayer germanene be-comes an indirect band gap semiconductor.This is an effective means to modulate the conversion of bilayer germanene between direct band gap semiconductor and indirect band gap semiconductor by adjusting the band structure of bilayer ger-manene effectively.The study of optical properties shows that the effect of warpage on the optical properties of bilayer ger-manene is mainly distributed in the ultraviolet and visible regions,and the warpage can effectively regulate the electronic struc-ture and optical properties of bilayer germanene.When the warpage is 0.069 nm,the first peak of dielectric function and extinc-tion coefficient is the largest,and the energy corresponding to the absorption band edge is the smallest.Therefore,the elec-tron utilization rate is the best when the warpage is 0.069 nm.

关键词： bilayer germanene warpages electronic structure optical properties first-principles

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Structural and optical properties evolution in pressure-induced amorphization of metal-organic framework ZIF-8

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Chinese Optics Letters 2022年第9期20卷 49-54页

作者：黄鑫何进姜益光陈卓成段星张龙 CAS Key Laboratory of Materials for High Power Laser Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China College of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences(UCAS)Beijing 100049China Hangzhou Institute for Advanced Study UCASHangzhou 310024China School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China Center of Advanced Optoelectronic Materials and Devices Key Laboratory of Novel Materials for Sensor of Zhejiang ProvinceCollege of Materials and Environmental EngineeringHangzhou Dianzi UniversityHangzhou 310018China Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghai 200240China

Zeolitic imidazolate framework-8(ZIF-8),a metal-organic framework(MOF)with a non-centrosymmetric crystal structure,exhibits nonlinear optics(NLO)properties and can act as the nanoporous matrix of guest molecules.Amorphization of ZIF-8 can be achieved by pressure or high temperature.Both crystalline and amorphous states have their inherent features for optical applications.The effects of the crystalline-amorphous transition on the structural and optical properties under pressure were investigated in detail.Amorphization leads to the destruction of the ZIF-8 lattice structure,collapse of pores,and the change of spatial symmetry,which in turn alters the NLO properties of ZIF-8 and the luminescence properties of the guest Eu cations.Our results establish the structure–optical properties relationship in the amorphization process and provide new clues in designing novel MOFs optical materials.

关键词： ZIF-8 structure optical properties pressure

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Tailoring of structural,optical and electrical properties of anatase TiO_(2)via doping of cobalt and nitrogen ions

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Journal of Materials Science & Technology 2022年第16期111卷 287-297页

作者： Anchal Sharma Puneet Negi Ruhit Jyoti Konwar Hemaunt Kumar Yogita Verma Shailja Prakash Chandra Sati Bhargav Rajyaguru Himanshu Dadhich N.A.Shah P.S.Solanki Department of Physics Eternal UniversityBaru SahibHimachal Pradesh173101India Centre of Excellence in Energy Science and Technology Shoolini UniversitySolanHimachal Pradesh173229India Department of Applied Science and Humanities Rajkiya Engineering CollegeBijnorUttar Pradesh246725India Department of Physics Rajiv Gandhi Government Post Graduate CollegeMandsaurMadhya Pradesh458001India Department of Physics Saurashtra UniversityRajkot360005India

Pure(pristine)anatase and mono–doped and co–doped derivatives of TiO_(2)having nitrogen(N)and cobalt(Co)as dopants with respective fixed doping concentrations of 0.7 mol.%and 1.0 mol.%were synthesized using auto–combustion sol–gel technique.The doping effects at corresponding non–metal and transition metal sites of TiO_(2)on the basis of the structural,optical and electrical properties have been investigated.X–ray diffraction(XRD)measurement confirms the formation of pure anatase phase of TiO_(2)for all samples having I41/amd space group of tetragonal structure which has been also verified by the Raman spectroscopy measurement.Various crystallographic parameters have been calculated by performing Rietveld refinement of XRD data including average crystallite size that has been observed in the range of10–15 nm.Pure anatase phase indicates the incorporation of Co^(2+)into TiO_(2)lattice which assists the substitution of N in place of oxygen in co–doped TiO_(2).The band gap tuning towards the visible region from3.2 to 2.1 e V has been achieved with mono–doping and co–doping of the N and Co in TiO_(2)lattice.This can be described in terms of the formation of localized levels of N–2p and Co–3d states in mono–doping and an isolated intermediate band formation in co–doping case.Electrical properties have been investigated in details and explained as the synergetic effects of structural and inherent ionic characters of various dopants.The observed band gaps of all doped samples lie within the visible region which makes them pertinent as the solar energy harnessing materials for photocatalytic and photovoltaic applications.

关键词： TiO_(2) Sol–Gel X–ray diffraction Electrical properties optical properties

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