We report on the discovery of unusual broad absorption lines(BALs)in the bright quasar SDSS J075133.35+134548.3 at z~1,using archival and newly obtained optical and NIR spectroscopic data.The BALs are detected reliabl...We report on the discovery of unusual broad absorption lines(BALs)in the bright quasar SDSS J075133.35+134548.3 at z~1,using archival and newly obtained optical and NIR spectroscopic data.The BALs are detected reliably in HeⅠ*λ3889,HeⅠ*λ10830 and tentatively in AlⅢ,MgⅡ.These BALs show complex velocity structures consisting of two major components:a high-velocity component(HV),with a blueshifted velocity range ofΔv_(HV)~9300--3500 km s^(-1),which can be reliably detected in HeⅠ*λ10830,and tentatively in AlⅢand MgⅡ,whereas it is undetectable in HeⅠ*λ3889;and a low-velocity component(LV),withΔv_(LV)~3500--1800 km s^(-1),is only detected in HeⅠ*λ3889 and HeⅠ*λ10830.With the BALs from different ions,the HV outflowing gas can be constrained to have a density of nH~10^(10.3)-10^(11.4) cm^(-3),a column density of NH~10^(21) cm^(-2)and an ionization parameter of U~10^(-1.83)-10^(-1.72);inferring a distance of RHV~0.5 pc from the central continuum source with a monochromatic luminosityλLλ(5100)=7.0×10^(45)erg s^(-1)at 5100 A.This distance is remarkably similar to that of the normal broad line region(BLR)estimated from reverberation experiments,suggesting association of the BLR and the HV BAL outflowing gas.Interestingly,a blueshifted component is also detected in AlⅢand MgⅡbroad emission lines(BELs),and the AlⅢ/MgⅡof such a BEL component can be reproduced by the physical parameters inferred from the HV BAL gas.The LV BAL gas likely has a larger column density,a higher ionization level and hence a smaller distance than the HV BAL gas.Further spectroscopy with a high S/N ratio and broader wavelength coverage is needed to confirm this to shed new light on the possible connection between BALs and BELs.展开更多
The donor–acceptor(D–A)copolymers,which exhibit wide broad absorption and intensified light-harvesting,are highly captivating for applications in solar conversion and optoelectronics.However,designing a polymer stru...The donor–acceptor(D–A)copolymers,which exhibit wide broad absorption and intensified light-harvesting,are highly captivating for applications in solar conversion and optoelectronics.However,designing a polymer structure that can achieve these photophysical properties simultaneously remains a challenge.Herein,we report two novel cyanated units 4-cyanobenzo[1,2-b:6,5-b′:3,4-c″]trithiophene(CBT)and 4,6-dicyanobenzo[1,2-b:6,5-b′:3,4-c″]trithiophene(C2BT)and their corresponding polymers,PCBT and PC2BT.Very interestingly,the PC2BT exhibited a broad absorption band with full width at half maxima(FWHM)of its absorption spectra,almost twice wider than PCBT and benchmark polymers PM6 and D18.Moreover,the PC2BT demonstrated intensified light-harvesting and long-lived exciton.Our in-depth investigation unveiled that the presence of dicyano substitutions induced a strong intramolecular charge transfer(ICT),which,in turn,resulted in the formation of favorable photophysical properties.Therefore,PC2BT-based polymer solar cells(PSCs)exhibited an efficiency of 18.06%,which was a record-setting efficiency for cyanated polymers.This study suggests an efficient strategy for enhancing ICT to design polymers toward favorable photophysical properties and excellent photovoltaic performance.展开更多
One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-cataly...One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-catalyzed Stille-coupling polymerizations.Thermal stability,X-ray diffraction analyses,UV-vis absorption spectra,photoluminescence spectra and electrochemical properties of the copolymers were investigated.The band gap estimated from UV-vis-NIR spectra of the copolymers films varied from 1.39 to 1.94 eV.Among these copolymers,the films of PBTT-T3T and PBTT,which contain the 5,6-dinitrobenzothiadiazole unit,cover a broad wavelength range in the visible and near-infrared region from 400 to 1000 nm with the maximal peak absorption around 700 nm,which is exactly matched with the maximum in the photon flux of the sun.展开更多
The ultraviolet broad absorption lines have been seen in the spectra of quasars at high redshift, and are generally considered to be caused by outflows with velocities from thousands kilometers per second to one tenth...The ultraviolet broad absorption lines have been seen in the spectra of quasars at high redshift, and are generally considered to be caused by outflows with velocities from thousands kilometers per second to one tenth of the speed of light. They provide crucial implications for the cosmological structures and physical evolutions related to the feedback of active galactic nuclei(AGNs).Recently, through a dedicated program of optically spectroscopic identifications of selected quasar candidates at redshift 5 by using the Lijiang 2.4 m telescope, we discovered two luminous broad absorption line quasars(BALQSOs) at redshift about 4.75. One of them may even have the potentially highest absorption Balnicity Index(BI) ever found to date, which is remarkably characterized by its deep, broad absorption lines and sub-relativistic outflows. Further physical properties, including the metal abundances,variabilities, evolutions of the supermassive black holes(SMBH) and accretion disks associated with the feedback process, can be investigated with multi-wavelength follow-up observations in the future.展开更多
The advent of“intelligent era”brings our life more convenience,but the electromagnetic radiation sur-rounding us not only greatly threatens human health,also makes information leakage and hidden trouble to national ...The advent of“intelligent era”brings our life more convenience,but the electromagnetic radiation sur-rounding us not only greatly threatens human health,also makes information leakage and hidden trouble to national defense security.Hence,it is very urgent to develop novel electromagnetic wave absorption materials with lightweight,strong absorption,tunable absorption frequency and broad band absorption.Herein,a novel electromagnetic wave absorber is obtained by constructing La_(0.8)CoO_(3)-rGO nanocompos-ite,where La_(0.8)CoO_(3)nanoparticles are anchored on graphene nanosheets by the electrostatic interaction between GO and La_(0.8)CoO_(3).The effect of hybridization ratio of La_(0.8)CoO_(3)and rGO on microwave ab-sorption properties is carefully studied.The optimal reflection loss of La_(0.8)CoO_(3)-rGO nanocomposite can reach-62.34 dB with the maximum effective bandwidth of 6.08 GHz,presenting 48.78%and 245.45%increment compared to bare La_(0.8)CoO_(3)nanoparticles,respectively.The effective absorption bandwidth covers a broad electromagnetic wave absorption band from Ku band to the C band by tailoring thickness of the absorbers from 2.4 mm to 4.4 mm.The fascinating electromagnetic wave absorption performance is attributed to the synergy effect of La_(0.8)CoO_(3)and rGO,which integrates magnetic and dielectric loss caused by resonance,conductance,relaxation,and scattering loss.This result confirms that La_(0.8)CoO_(3)-rGO nanocomposite is potential candidates toward high-efficiency microwave absorbers and provides a valuable pathway for designing high-performance microwave attenuation materials in the future.展开更多
The precise synthesis of subporphyrinoid hybrids withπ-expanded topologies and unique material properties plays a promising role in the design of functional macrocycles.Easy,selective,and controllable routes to boron...The precise synthesis of subporphyrinoid hybrids withπ-expanded topologies and unique material properties plays a promising role in the design of functional macrocycles.Easy,selective,and controllable routes to boron subphthalocyanine−subnaphthalocyanine hybrids,Bsub(Pc_(3‑p)-Nc_(p))s,are desirable for this purpose yet synthetically challenging due to random mixtures of C_(s-),C_(3v-),and,in some cases,C_(1)-symmetric compounds that form during traditional statistical mixed cyclotrimerizations.Herein,we addressed this issue by developing a sterically driven mixed cyclotrimerization with enhanced selectivity for the targeted C_(s)-symmetric hybrid and complete suppression of sterically crowded macrocyclic byproducts.This process,coupled with a rationally designed precursor bearing bulky phenyl substituents,enabled the synthesis and characterization of bay-position phenylated Ph_(2)-(R_(p))_(8)Bsub(Pc_(2)-Nc_(1))hybrids with halogens(Rp=Cl or F)in their peripheral isoindole rings.Reaction selectivity ranged between 59 and 72%with remarkable yields,significantly higher than that of conventional mixed cyclotrimerizations.These findings were augmented by theoretical calculations on precursor Lewis basicity as guiding principles into hybrid macrocycle formation.Additionally,the incorporation of unfused phenyl groups and halogen atoms into the hybrid framework resulted in fine-tuned optical,structural,electronic,and electrochemical properties.This straightforward approach achieved improved selectivity and controlled narrowing of the product distribution,affording the efficient synthesis of structurally sophisticated Bsub(Pc_(2)-Nc_(1))hybrids.This then expands the library of 3-dimensionalπ-extended macrocycles for use in a range of applications,such as in optoelectronic devices with precisely tailored optical properties.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,11573024,11473025,11421303,11573001and 11822301)the National Basic Research Program of China(the 973 Program 2013CB834905and 2015CB857005)+11 种基金supported by the NSFC(11503022)the Natural Science Foundation of Shanghai(No.15ZR 1444200)supported by the NSFC(11233002)support from the Anhui Provincial NSF(1608085QA06)Young Wanjiang Scholar programfunded by the Strategic Priority Research Programthe Emergence of Cosmological Structures(XDB09000000),National Astronomical Observatories,Chinese Academy of Sciencesthe Special Fund for Astronomy from the Ministry of FinanceFunding for SDSS-Ⅲhas been provided by the Alfred P.Sloan Foundationthe Participating Institutionsthe National Science Foundationthe U.S.Department of Energy Office of Science。
文摘We report on the discovery of unusual broad absorption lines(BALs)in the bright quasar SDSS J075133.35+134548.3 at z~1,using archival and newly obtained optical and NIR spectroscopic data.The BALs are detected reliably in HeⅠ*λ3889,HeⅠ*λ10830 and tentatively in AlⅢ,MgⅡ.These BALs show complex velocity structures consisting of two major components:a high-velocity component(HV),with a blueshifted velocity range ofΔv_(HV)~9300--3500 km s^(-1),which can be reliably detected in HeⅠ*λ10830,and tentatively in AlⅢand MgⅡ,whereas it is undetectable in HeⅠ*λ3889;and a low-velocity component(LV),withΔv_(LV)~3500--1800 km s^(-1),is only detected in HeⅠ*λ3889 and HeⅠ*λ10830.With the BALs from different ions,the HV outflowing gas can be constrained to have a density of nH~10^(10.3)-10^(11.4) cm^(-3),a column density of NH~10^(21) cm^(-2)and an ionization parameter of U~10^(-1.83)-10^(-1.72);inferring a distance of RHV~0.5 pc from the central continuum source with a monochromatic luminosityλLλ(5100)=7.0×10^(45)erg s^(-1)at 5100 A.This distance is remarkably similar to that of the normal broad line region(BLR)estimated from reverberation experiments,suggesting association of the BLR and the HV BAL outflowing gas.Interestingly,a blueshifted component is also detected in AlⅢand MgⅡbroad emission lines(BELs),and the AlⅢ/MgⅡof such a BEL component can be reproduced by the physical parameters inferred from the HV BAL gas.The LV BAL gas likely has a larger column density,a higher ionization level and hence a smaller distance than the HV BAL gas.Further spectroscopy with a high S/N ratio and broader wavelength coverage is needed to confirm this to shed new light on the possible connection between BALs and BELs.
基金supported by the National Natural Science Foundation of China(grant nos.22179076 and 22225504)the Department of Education of Guangdong Province,China(grant no.2021KCXTD032)+2 种基金the Natural Science Foundation of Guangdong Province,China(grant no.2022A1515011803)the Science and Technology Innovation Fund for College students in Guangdong Province,China(grant no.2020329105600A000003)Guangdong Provincial Key Laboratory of Catalysis,China(grant no.2020B121201002).
文摘The donor–acceptor(D–A)copolymers,which exhibit wide broad absorption and intensified light-harvesting,are highly captivating for applications in solar conversion and optoelectronics.However,designing a polymer structure that can achieve these photophysical properties simultaneously remains a challenge.Herein,we report two novel cyanated units 4-cyanobenzo[1,2-b:6,5-b′:3,4-c″]trithiophene(CBT)and 4,6-dicyanobenzo[1,2-b:6,5-b′:3,4-c″]trithiophene(C2BT)and their corresponding polymers,PCBT and PC2BT.Very interestingly,the PC2BT exhibited a broad absorption band with full width at half maxima(FWHM)of its absorption spectra,almost twice wider than PCBT and benchmark polymers PM6 and D18.Moreover,the PC2BT demonstrated intensified light-harvesting and long-lived exciton.Our in-depth investigation unveiled that the presence of dicyano substitutions induced a strong intramolecular charge transfer(ICT),which,in turn,resulted in the formation of favorable photophysical properties.Therefore,PC2BT-based polymer solar cells(PSCs)exhibited an efficiency of 18.06%,which was a record-setting efficiency for cyanated polymers.This study suggests an efficient strategy for enhancing ICT to design polymers toward favorable photophysical properties and excellent photovoltaic performance.
基金support from the National Natural Science Foundation of China (50933003 & 50903044)MOST of China (2009AA032304)
文摘One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-catalyzed Stille-coupling polymerizations.Thermal stability,X-ray diffraction analyses,UV-vis absorption spectra,photoluminescence spectra and electrochemical properties of the copolymers were investigated.The band gap estimated from UV-vis-NIR spectra of the copolymers films varied from 1.39 to 1.94 eV.Among these copolymers,the films of PBTT-T3T and PBTT,which contain the 5,6-dinitrobenzothiadiazole unit,cover a broad wavelength range in the visible and near-infrared region from 400 to 1000 nm with the maximal peak absorption around 700 nm,which is exactly matched with the maximum in the photon flux of the sun.
基金supported by the Strategic Priority Research Program"The emergence of Cosmological Structures"of the Chinese Academy of Sciences(Grant No.XDB09000000)the National Natural Science Foundation of China(Grant Nos.11373008,11133006 and 11361140347)
文摘The ultraviolet broad absorption lines have been seen in the spectra of quasars at high redshift, and are generally considered to be caused by outflows with velocities from thousands kilometers per second to one tenth of the speed of light. They provide crucial implications for the cosmological structures and physical evolutions related to the feedback of active galactic nuclei(AGNs).Recently, through a dedicated program of optically spectroscopic identifications of selected quasar candidates at redshift 5 by using the Lijiang 2.4 m telescope, we discovered two luminous broad absorption line quasars(BALQSOs) at redshift about 4.75. One of them may even have the potentially highest absorption Balnicity Index(BI) ever found to date, which is remarkably characterized by its deep, broad absorption lines and sub-relativistic outflows. Further physical properties, including the metal abundances,variabilities, evolutions of the supermassive black holes(SMBH) and accretion disks associated with the feedback process, can be investigated with multi-wavelength follow-up observations in the future.
基金supported by Natural Science Foundation of China(Nos.12074095,52273257,52177014,and 51977009)Heilongjiang Provincial Science Foundation for Distin-guished Young Scholars(No.JQ2022A002)2020 Central Govern-ment’s Plan to Support the Talent Training Project of the Reform and Development Fund of Local Universities(No.2020YQ02).
文摘The advent of“intelligent era”brings our life more convenience,but the electromagnetic radiation sur-rounding us not only greatly threatens human health,also makes information leakage and hidden trouble to national defense security.Hence,it is very urgent to develop novel electromagnetic wave absorption materials with lightweight,strong absorption,tunable absorption frequency and broad band absorption.Herein,a novel electromagnetic wave absorber is obtained by constructing La_(0.8)CoO_(3)-rGO nanocompos-ite,where La_(0.8)CoO_(3)nanoparticles are anchored on graphene nanosheets by the electrostatic interaction between GO and La_(0.8)CoO_(3).The effect of hybridization ratio of La_(0.8)CoO_(3)and rGO on microwave ab-sorption properties is carefully studied.The optimal reflection loss of La_(0.8)CoO_(3)-rGO nanocomposite can reach-62.34 dB with the maximum effective bandwidth of 6.08 GHz,presenting 48.78%and 245.45%increment compared to bare La_(0.8)CoO_(3)nanoparticles,respectively.The effective absorption bandwidth covers a broad electromagnetic wave absorption band from Ku band to the C band by tailoring thickness of the absorbers from 2.4 mm to 4.4 mm.The fascinating electromagnetic wave absorption performance is attributed to the synergy effect of La_(0.8)CoO_(3)and rGO,which integrates magnetic and dielectric loss caused by resonance,conductance,relaxation,and scattering loss.This result confirms that La_(0.8)CoO_(3)-rGO nanocomposite is potential candidates toward high-efficiency microwave absorbers and provides a valuable pathway for designing high-performance microwave attenuation materials in the future.
文摘The precise synthesis of subporphyrinoid hybrids withπ-expanded topologies and unique material properties plays a promising role in the design of functional macrocycles.Easy,selective,and controllable routes to boron subphthalocyanine−subnaphthalocyanine hybrids,Bsub(Pc_(3‑p)-Nc_(p))s,are desirable for this purpose yet synthetically challenging due to random mixtures of C_(s-),C_(3v-),and,in some cases,C_(1)-symmetric compounds that form during traditional statistical mixed cyclotrimerizations.Herein,we addressed this issue by developing a sterically driven mixed cyclotrimerization with enhanced selectivity for the targeted C_(s)-symmetric hybrid and complete suppression of sterically crowded macrocyclic byproducts.This process,coupled with a rationally designed precursor bearing bulky phenyl substituents,enabled the synthesis and characterization of bay-position phenylated Ph_(2)-(R_(p))_(8)Bsub(Pc_(2)-Nc_(1))hybrids with halogens(Rp=Cl or F)in their peripheral isoindole rings.Reaction selectivity ranged between 59 and 72%with remarkable yields,significantly higher than that of conventional mixed cyclotrimerizations.These findings were augmented by theoretical calculations on precursor Lewis basicity as guiding principles into hybrid macrocycle formation.Additionally,the incorporation of unfused phenyl groups and halogen atoms into the hybrid framework resulted in fine-tuned optical,structural,electronic,and electrochemical properties.This straightforward approach achieved improved selectivity and controlled narrowing of the product distribution,affording the efficient synthesis of structurally sophisticated Bsub(Pc_(2)-Nc_(1))hybrids.This then expands the library of 3-dimensionalπ-extended macrocycles for use in a range of applications,such as in optoelectronic devices with precisely tailored optical properties.
