The emeraldine base form of polyaniline (PANI) can be doped by a photo-induceddoping method. In this method a copolymer of vinylidene chloride and methyl acrylate(VCMAC) was used as photo acid generator which can ...The emeraldine base form of polyaniline (PANI) can be doped by a photo-induceddoping method. In this method a copolymer of vinylidene chloride and methyl acrylate(VCMAC) was used as photo acid generator which can release proton when it is exposedto ultraviolet light (λ= 254 nm). The structure of PANI-VCMAC system before and afterirradiation was characterized by elemental analysis, IR, XPS, and SEM images. Resultsobtained indicate that the photo-induced doping characteristics, such as doping positionand type of charge carriers, are similar to that of PANI doped with HCl. The poor room-temperature conductivity (~10<sup>-5</sup>S/cm) of PANI-VCMAC system after irradiation maybe due to low doping degree (~pH= 3) and the difference in morphology as compared withPANI-HCl film.展开更多
The investigation of electrical properties in alexandrite (BeAl<sub>2</sub>O<sub>4</sub>:Cr<sup>3+</sup>) in synthetic and natural forms is presented in this paper. Alexandrite is a...The investigation of electrical properties in alexandrite (BeAl<sub>2</sub>O<sub>4</sub>:Cr<sup>3+</sup>) in synthetic and natural forms is presented in this paper. Alexandrite is a rare and precious mineral that changes color according to the light incident on it. In the synthetic form, it is used technologically as an active laser medium. The electrical characterization was obtained using the Thermally Stimulated Depolarization Current (TSDC) technique, an interesting tool to study the behavior of impurities in insulators. Alexandrite presented the electric dipole relaxation phenomenon, both in natural and in synthetic samples. It was possible to observe TSDC bands for the synthetic sample at around 170 K, and at around 175 K for the natural sample. Besides, photo-induced TSDC measurements were performed through the excitement of the samples by using a continuous wave argon laser. In addition, photoluminescence measurements were performed to verify in advance whether the laser light would be absorbed by the sample, and in order to complement the photo-induced TSDC measurements analysis. The results of photo-induced TSDC experiments have contributed to the understanding of the TSDC bands behavior: the results obtained with the technique suggest that there is an effective participation of Cr<sup>3+</sup> ions in the formation of TSDC bands because they were more intense when the sample was exposed to the argon laser beam.展开更多
By using first-principles simulations based on time-dependent density functional theory,the chemical reaction of an HCl molecule encapsulated in C60induced by femtosecond laser pulses is observed.The H atom starts to ...By using first-principles simulations based on time-dependent density functional theory,the chemical reaction of an HCl molecule encapsulated in C60induced by femtosecond laser pulses is observed.The H atom starts to leave the Cl atom and is reflected by the C60wall.The coherent nuclear dynamic behaviors of bond breakage and recombination of the HCl molecule occurring in both polarized parallel and perpendicular to the H–Cl bond axis are investigated.The radial oscillation is also found in the two polarization directions of the laser pulse.The relaxation time of the H–Cl bond lengths in transverse polarization is slow in comparison with that in longitudinal polarization.Those results are important for studying the dynamics of the chemical bond at an atomic level.展开更多
Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lowe...Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1%,which is 10.4 times higher than that of h-CDs(4.9%),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly enhanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.展开更多
A photo-induced de-oxygenation process of myoglobin (Mb) in aqueous solution was investigated by use of fluorescence spectroscopy. The spectra are characterized by the fluorescence intensity declining gradually after ...A photo-induced de-oxygenation process of myoglobin (Mb) in aqueous solution was investigated by use of fluorescence spectroscopy. The spectra are characterized by the fluorescence intensity declining gradually after each scan,and the decay of fluorescence intensity being significant in each scan,which is assigned to the release of oxygen from the opening of the heme-pockets induced by illumination. More illumination will cause more release of oxygen; if the temperature of an Mb solution is increased when it is illuminated,the rate of de-oxygenation will be higher. It was found that ligand-oxygen in Fe-porphyrin could be removed from Mb by nitrogen. This indicates that the interac-tion between oxy-Mb and other different gases can be tested by the method of fluorescence spectros-copy. In addition,fluorescence spectroscopy can be employed to probe the energy transfer between Fe-porphyrin and tryptophan or tyrosine in Mb molecules.展开更多
It is helpful to study the photo-induced effect in the perovskite manganites not only for elucidating the mechanism of colossal magnetoresistance (CMR) effect but also for potential applications in technology. The las...It is helpful to study the photo-induced effect in the perovskite manganites not only for elucidating the mechanism of colossal magnetoresistance (CMR) effect but also for potential applications in technology. The laser-induced effect in the Co doping layered perovskite manganites La1.2Sr1.8Mn1.8Co0.2O7 is studied in this paper and the obtained results are also compared with that gained in the Nd-doping manganites with cubic perovskite structure.展开更多
In this paper, we report a novel method for accurately measuring the photo-induced birefringence of photosensitive fiber by using Mach-Zehnder interferometer. The results indicate that the normalized birefringence can...In this paper, we report a novel method for accurately measuring the photo-induced birefringence of photosensitive fiber by using Mach-Zehnder interferometer. The results indicate that the normalized birefringence can attain 10-5.展开更多
A novel mononuclear cobalt complex 1 was synthesized by treatment of CoC12o6H20 with a COOMe func-tionalized TPA ligand (TPA=tris(2-pyridylmethyl)amine). In a basic borate buffer, 1 acts as an efficient catalyst f...A novel mononuclear cobalt complex 1 was synthesized by treatment of CoC12o6H20 with a COOMe func-tionalized TPA ligand (TPA=tris(2-pyridylmethyl)amine). In a basic borate buffer, 1 acts as an efficient catalyst forwater oxidation, which is confirmed by an extinct catalytic oxidant wave in electrochemistry. Visible light-drivenwater oxidation has been achieved by 1 with a TON of 127.7 and a TOF of 3.8 s^-1 respectively in a homogeneoussystem. In comparison to the reference RC with naked TPA, the higher efficiency of 1 evidences COOMe on ligandcan improve the catalytic efficiency, leading to an effective pathway towards construction of a robust and stable ar-tificial photosynthesis system.展开更多
Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry.Presently,the industrial manufacture of benzoic acids and benzene polycarboxylic acids(BPCAs)is mainly bas...Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry.Presently,the industrial manufacture of benzoic acids and benzene polycarboxylic acids(BPCAs)is mainly based on the deep oxidation of polyalkyl benzene,which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting Me Br and corrosion hazards of production equipment.In this report,photo-induced deep aerobic oxidation of(poly)alkyl benzene to benzene(poly)carboxylic acids was developed.CeCl_(3) was proved to be an efficient HAT(hydrogen atom transfer)catalyst in the presence of alcohol as both hydrogen and electron shuttle.Dioxygen(O_(2))was found as a sole terminal oxidant.In most cases,pure products were easily isolated by simple filtration,implying large-scale implementation advantages.The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks.展开更多
A number of electron donors, acceptors and diads containing xanthene dyes were sythesized. When the dyes were excited, the rate constants and the efficiencies of the intermolecular and intramolecular photo-induced ele...A number of electron donors, acceptors and diads containing xanthene dyes were sythesized. When the dyes were excited, the rate constants and the efficiencies of the intermolecular and intramolecular photo-induced electron transfer reactions were determined and calculated. It is found that the photo-induced electron transfer reactions occurred between xanthene dyes and many, including very weak donors or acceptors. The rate constants of intermolecular reactions were controlled by diffusion, and influenced by the reactant concentrations. The laser flash experiments showed that for low reactant concentrations, this kind of reactions took place mainly via the triplet excited state of the dyes. If different electric charges exist with dyes and donors/acceptors, there will be static quenching of the dyes’ fluorescence. The intramolecular electron transfer reactions are independent of the solution concentrations, and they may directly proceed via the singlet excited state of the dyes effectively.展开更多
Introducing inorganic cation into hybrid organic-inorganic perovskites(HOIPs)has attracted great attention because of the enhancement stabilities without sacrificing their excellent optoelectronic properties.Here,we i...Introducing inorganic cation into hybrid organic-inorganic perovskites(HOIPs)has attracted great attention because of the enhancement stabilities without sacrificing their excellent optoelectronic properties.Here,we introduce Cs and Rb into MAPbI_(1.8)Br_(1.2)single crystals(SCs)to dig out the mixed cation effect on optoelectronic performances and phase stabilities.Both Rb and Cs can increase the lattice capacity,which is sufficient to relieve the lattice stress caused by photon energy,thus achieving the purpose of stabilizing the lattice structure and inhibiting migration of halide ions,compared with MAPbI_(1.8)Br_(1.2)SC.On the other hand,the smaller polarity of Rb and Cs reduces the electron-phonon coupling,thus significantly inhibiting the migration of halide ions.Meanwhile,through planar photo-detectors,MA_(0.9)Cs_(0.1)PbI_(1.8)Br_(1.2)-based device behaves much excellent optoelectronic performance(R=0.170 A/W,EQE=51.39%,D^(*)=4.42×10^(12)Jones,on/off ratio:~522).展开更多
We reveal here a visible-light promoted phosphorylation of 2-isocyanoaryl thioethers for the first time with concomita nt C(sp3)-S bond cleavage and imidoyl C-S fo rmation.Additionally,this method features the use of ...We reveal here a visible-light promoted phosphorylation of 2-isocyanoaryl thioethers for the first time with concomita nt C(sp3)-S bond cleavage and imidoyl C-S fo rmation.Additionally,this method features the use of 3 mol%organic dye Rose Bengal as the photocatalyst without external transition-metal or peroxide oxidants,and provides a novel and environmentally friendly approach for the preparation of a variety of 2-phosphoryl benzothiazoles in moderate to good yields.展开更多
Photo-induced vacancy defects are employed strategically to imbue semiconductors with enhanced performance characteristics for many important applications such as surface-enhanced Raman scattering(SERS)sensing,photoca...Photo-induced vacancy defects are employed strategically to imbue semiconductors with enhanced performance characteristics for many important applications such as surface-enhanced Raman scattering(SERS)sensing,photocatalysis,and photovoltaic applications.However,the long-term maintenance and use of photo-induced vacancy defects remain elusive,because of their rapid self-healing upon air exposure.In this study,we demonstrate that photo-induced oxygen vacancy(PIVO)defects can be stabilized by the photoexcitation of metal–organic framework(MOF)materials,which is crucial for SERS analysis.The PIVO defects in MOF materials are stable for at least two weeks in the ambient atmosphere,owing to the combination of steric hindrance and electron delocalization around vacancy defects,which significantly contrasts the short lifetime(within minutes)of PIVO defects in metal-oxide semiconductors.With the formation of stable PIVO defects,a prominent SERS enhancement surpassing that of pristine MOFs is achieved,accompanied with a reduced limit of detection by three orders of magnitude.Moreover,the additional SERS enhancement rendered by PIVO defects can be stably retained and is effective for monitoring various small molecules,such as dopamine and bisphenol A.展开更多
This study aimed to clarify the synergistic phototactic attraction-repulsion effect formed by the photo-induced approach-avoidance behavior of thrips,construct phototactic attraction-repulsion light control technologi...This study aimed to clarify the synergistic phototactic attraction-repulsion effect formed by the photo-induced approach-avoidance behavior of thrips,construct phototactic attraction-repulsion light control technologies.The phototactic push-pull effects of red light and UV(365 nm),violet(405 nm),green(520 nm),and yellow(560 nm)single light,as well as their pairwise combined light on the behavior of western flower thrips were investigated using an apparatus that measured thrips response.The study also analyzed the influence of light properties on the phototactic attraction-repulsion effects of thrips and the synergistic effects of red light,and the attraction-repulsion regulation mode.The influence factors on the photo-induced attraction-repulsion effect of thrips were also discussed.The results showed that the red light,presenting the push effect,drove thrips to respond to the sensitive light.The synergistic attraction-repulsion effect of red light and singlelight,as well as that of red light and combined light was related to the light intensity.However,the attraction-repulsion synergism did not reflect thrips response effect and approach effect pulled and pushed by red light and single light,red light and combined light.Thrips preference for green-yellow light,and their behavior depended on the degree of UV light,making the attraction-repulsion synergy of red and green light the strongest.When the light intensity increased,the attraction-repulsion synergy of red and yellow light was the strongest.The attraction-repulsion response to red light and single light was related to the spectral attribute of the single light,with that of red lightand UV light being better.The attraction-repulsion response to red light and combined light was related to light intensity.The intensity of combined light made the attraction-repulsion response to red light and the combined UV and violet light be the best,and the brightness of long-short spectrum light rendered red light and the combined UV and yellow light the best.All such light and combinations were remarkably better than that of red light and UV light.Relative to red light and UV light,the use ofred light and combined light provided limited enhancement to the approach effect of thrips;however,under red light and combined light,violet light intensified the approach of thrips to UV light,with yellow light strengthening the approach to green light.Those results provided a scientific basis for the development of light trapping equipment and the adjustment of light control strategies for thrips.展开更多
Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interact...Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump–probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photoinduced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light–free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams.展开更多
Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecu...Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecular adsorption and controllable molecular orientation.However,it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate.Herein,we demonstrate a graphene oxide(GO)energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity.The Fermi level(Ef)of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate.Experimentally,kelvin probe force microscopy(KPFM)is employed to quantitatively analyze the Ef of GO.Theoretically,the density functional theory calculations are also performed to verify the proposed modulation mechanism.Consequently,the SERS response of probe molecules with different band structures(R6G,CV,MB,PNTP)can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate.This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.展开更多
Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catal...Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization,fast migration of charge carriers,efficient surface redox reactions and good electrical conductivity.In this review,we summarize the fabrication methods of CDs and corresponding CD nanocomposites,including the strategies of surface modification and heteroatom doping.The properties of CDs that concerned to the photo-and electro-catalysis are highlighted and detailed corresponding applications are listed.More importantly,as new non-contact detection technologies,transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics,which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts.The development and application of the techniques are reviewed.Finally,we discuss and outline the major challenges and opportunities for future CD-based catalysts,and the needs and expectations for the development of novel characterization technologies.展开更多
Ciprofloxacin(CIP), moxifoxacin(MOX) and enrofloxacin(ENR) were selected as typical fluoroquinolones(FQs) to analyze the excitation-enhancing effect and mechanism of solvents on FQs' electron transition based on q...Ciprofloxacin(CIP), moxifoxacin(MOX) and enrofloxacin(ENR) were selected as typical fluoroquinolones(FQs) to analyze the excitation-enhancing effect and mechanism of solvents on FQs' electron transition based on quantum chemical calculations. The UV spectra of three FQs in gas and five different solvents(water, cyclohexane, dimethylsulfoxide, methanol, acetone) were calculated using Gaussian 09 software. The transition mechanisms of FQs' main electron transitions were analyzed by natural bond orbital(NBO) theory, and the solvent effect on each electron transition was assessed qualitatively and quantitatively by sensitivity analysis and an established index system. The excitation enhancing mechanism of solvent on electron transitions of FQs was analyzed from the view of photo-induced reactions between solvent and FQs molecules. The results show that there are two main transitions located in the spectrum ranges of 300~380 and 240~300 nm for each FQ in any medium, which are assigned as n →π* and π→π* electron transitions, respectively. By comparison, the n →π* transition is more sensitive to solvent because of the energy transfer between solvent molecules and FQs, but the solvent effect on the π→π* transition is stronger than on the n →π* transition. The sequence of affected extent of solvent effect on electron transition was CIP > MOX > ENR, and the sequence of solvent effect was water > DMSO > methanol > acetone > cyclohexane(stronger solvent effect with increasing the dielectric constant of solvent). From the view of photo-induced reactions, the reaction between FQs*T1 and solvent*T1 has the decisive regulatory effect on the n →π* transition of FQs in solvent, and the reaction between FQsS0 and solvent*TI has an enhancing effect on the π→π* transition.展开更多
Electrostatic layer-by-layer self-assembly multilayer films were successfully fabricated from C60-ethylenediamineadduct (C60-EDA) and DNA. Under visible light irradiation, DNA is ready to be cleaved and the films are ...Electrostatic layer-by-layer self-assembly multilayer films were successfully fabricated from C60-ethylenediamineadduct (C60-EDA) and DNA. Under visible light irradiation, DNA is ready to be cleaved and the films are destroyed.展开更多
An efficient pyrene-Schiff base fluorescent sensor PySb was synthesized and evaluated for its fluorescence response to metal ions. Sensor PySb exhibits an “off-on-type” mode with high selectivity to Zn2+ and Al3+ in...An efficient pyrene-Schiff base fluorescent sensor PySb was synthesized and evaluated for its fluorescence response to metal ions. Sensor PySb exhibits an “off-on-type” mode with high selectivity to Zn2+ and Al3+ in ethanol (470 nm) and in dimethyl sulfoxide (458 nm) respectively. The originally non-fluorescent PySb, due to photo-induced electron transfer (PET) from imine moiety, is turned on after binding with the cations. The stoichiometric ratio between PySb and Zn2+ is 1:2;moreover, the limit of detection (LOD) and bonding constant were 2.39 × 10-8 M and 2 × 109 M-1 respectively, as obtained from titration experiments.展开更多
基金The work was supported by the National Natural Science Foundation of China
文摘The emeraldine base form of polyaniline (PANI) can be doped by a photo-induceddoping method. In this method a copolymer of vinylidene chloride and methyl acrylate(VCMAC) was used as photo acid generator which can release proton when it is exposedto ultraviolet light (λ= 254 nm). The structure of PANI-VCMAC system before and afterirradiation was characterized by elemental analysis, IR, XPS, and SEM images. Resultsobtained indicate that the photo-induced doping characteristics, such as doping positionand type of charge carriers, are similar to that of PANI doped with HCl. The poor room-temperature conductivity (~10<sup>-5</sup>S/cm) of PANI-VCMAC system after irradiation maybe due to low doping degree (~pH= 3) and the difference in morphology as compared withPANI-HCl film.
文摘The investigation of electrical properties in alexandrite (BeAl<sub>2</sub>O<sub>4</sub>:Cr<sup>3+</sup>) in synthetic and natural forms is presented in this paper. Alexandrite is a rare and precious mineral that changes color according to the light incident on it. In the synthetic form, it is used technologically as an active laser medium. The electrical characterization was obtained using the Thermally Stimulated Depolarization Current (TSDC) technique, an interesting tool to study the behavior of impurities in insulators. Alexandrite presented the electric dipole relaxation phenomenon, both in natural and in synthetic samples. It was possible to observe TSDC bands for the synthetic sample at around 170 K, and at around 175 K for the natural sample. Besides, photo-induced TSDC measurements were performed through the excitement of the samples by using a continuous wave argon laser. In addition, photoluminescence measurements were performed to verify in advance whether the laser light would be absorbed by the sample, and in order to complement the photo-induced TSDC measurements analysis. The results of photo-induced TSDC experiments have contributed to the understanding of the TSDC bands behavior: the results obtained with the technique suggest that there is an effective participation of Cr<sup>3+</sup> ions in the formation of TSDC bands because they were more intense when the sample was exposed to the argon laser beam.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11074176 and 10976019)the Doctoral Program of Higher Education of China(Grant No.20100181110080)
文摘By using first-principles simulations based on time-dependent density functional theory,the chemical reaction of an HCl molecule encapsulated in C60induced by femtosecond laser pulses is observed.The H atom starts to leave the Cl atom and is reflected by the C60wall.The coherent nuclear dynamic behaviors of bond breakage and recombination of the HCl molecule occurring in both polarized parallel and perpendicular to the H–Cl bond axis are investigated.The radial oscillation is also found in the two polarization directions of the laser pulse.The relaxation time of the H–Cl bond lengths in transverse polarization is slow in comparison with that in longitudinal polarization.Those results are important for studying the dynamics of the chemical bond at an atomic level.
基金the National Natural Science Foundation of China(Nos.U1833202 and 21876117)the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University(No.2021YB05).
文摘Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1%,which is 10.4 times higher than that of h-CDs(4.9%),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly enhanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.
基金the National Natural Science Foundation of China (Grant No. 2021010)Program for Liaoning Excellent Talents in University (Grant No. RC-04-10)
文摘A photo-induced de-oxygenation process of myoglobin (Mb) in aqueous solution was investigated by use of fluorescence spectroscopy. The spectra are characterized by the fluorescence intensity declining gradually after each scan,and the decay of fluorescence intensity being significant in each scan,which is assigned to the release of oxygen from the opening of the heme-pockets induced by illumination. More illumination will cause more release of oxygen; if the temperature of an Mb solution is increased when it is illuminated,the rate of de-oxygenation will be higher. It was found that ligand-oxygen in Fe-porphyrin could be removed from Mb by nitrogen. This indicates that the interac-tion between oxy-Mb and other different gases can be tested by the method of fluorescence spectros-copy. In addition,fluorescence spectroscopy can be employed to probe the energy transfer between Fe-porphyrin and tryptophan or tyrosine in Mb molecules.
基金supported by the National Key Basic Research,and the National Natural Science Foundation of China(Grant Nos.10174085&10074066)Anhui Province NSF(Grant Nos.00046115&03046201)the Fundamental Bureau,Chinese Academy of Sciences.
文摘It is helpful to study the photo-induced effect in the perovskite manganites not only for elucidating the mechanism of colossal magnetoresistance (CMR) effect but also for potential applications in technology. The laser-induced effect in the Co doping layered perovskite manganites La1.2Sr1.8Mn1.8Co0.2O7 is studied in this paper and the obtained results are also compared with that gained in the Nd-doping manganites with cubic perovskite structure.
基金Supported by the National "863" high technology project(2002AA313110)
文摘In this paper, we report a novel method for accurately measuring the photo-induced birefringence of photosensitive fiber by using Mach-Zehnder interferometer. The results indicate that the normalized birefringence can attain 10-5.
文摘A novel mononuclear cobalt complex 1 was synthesized by treatment of CoC12o6H20 with a COOMe func-tionalized TPA ligand (TPA=tris(2-pyridylmethyl)amine). In a basic borate buffer, 1 acts as an efficient catalyst forwater oxidation, which is confirmed by an extinct catalytic oxidant wave in electrochemistry. Visible light-drivenwater oxidation has been achieved by 1 with a TON of 127.7 and a TOF of 3.8 s^-1 respectively in a homogeneoussystem. In comparison to the reference RC with naked TPA, the higher efficiency of 1 evidences COOMe on ligandcan improve the catalytic efficiency, leading to an effective pathway towards construction of a robust and stable ar-tificial photosynthesis system.
基金supported by the National Natural Science Foundation of China(21988101,21761132027,22071029,U19B6002)the Science and Technology Commission of Shanghai Municipality(19XD1400800,18JC1411300)+2 种基金Shanghai Municipal Education Commission(2017-01-07-00-07-E00058)Key-Area Research and Development Program of Guangdong Province(2020B010188001)Shanghai Gaofeng&Gaoyuan Project for University Academic Program Development。
文摘Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry.Presently,the industrial manufacture of benzoic acids and benzene polycarboxylic acids(BPCAs)is mainly based on the deep oxidation of polyalkyl benzene,which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting Me Br and corrosion hazards of production equipment.In this report,photo-induced deep aerobic oxidation of(poly)alkyl benzene to benzene(poly)carboxylic acids was developed.CeCl_(3) was proved to be an efficient HAT(hydrogen atom transfer)catalyst in the presence of alcohol as both hydrogen and electron shuttle.Dioxygen(O_(2))was found as a sole terminal oxidant.In most cases,pure products were easily isolated by simple filtration,implying large-scale implementation advantages.The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks.
文摘A number of electron donors, acceptors and diads containing xanthene dyes were sythesized. When the dyes were excited, the rate constants and the efficiencies of the intermolecular and intramolecular photo-induced electron transfer reactions were determined and calculated. It is found that the photo-induced electron transfer reactions occurred between xanthene dyes and many, including very weak donors or acceptors. The rate constants of intermolecular reactions were controlled by diffusion, and influenced by the reactant concentrations. The laser flash experiments showed that for low reactant concentrations, this kind of reactions took place mainly via the triplet excited state of the dyes. If different electric charges exist with dyes and donors/acceptors, there will be static quenching of the dyes’ fluorescence. The intramolecular electron transfer reactions are independent of the solution concentrations, and they may directly proceed via the singlet excited state of the dyes effectively.
基金financially supported by the National Natural Science Foundation of China(No.52072225)supported by the Project of Shandong Province Higher Educational Young Innovative Talent Introduction and Cultivation。
文摘Introducing inorganic cation into hybrid organic-inorganic perovskites(HOIPs)has attracted great attention because of the enhancement stabilities without sacrificing their excellent optoelectronic properties.Here,we introduce Cs and Rb into MAPbI_(1.8)Br_(1.2)single crystals(SCs)to dig out the mixed cation effect on optoelectronic performances and phase stabilities.Both Rb and Cs can increase the lattice capacity,which is sufficient to relieve the lattice stress caused by photon energy,thus achieving the purpose of stabilizing the lattice structure and inhibiting migration of halide ions,compared with MAPbI_(1.8)Br_(1.2)SC.On the other hand,the smaller polarity of Rb and Cs reduces the electron-phonon coupling,thus significantly inhibiting the migration of halide ions.Meanwhile,through planar photo-detectors,MA_(0.9)Cs_(0.1)PbI_(1.8)Br_(1.2)-based device behaves much excellent optoelectronic performance(R=0.170 A/W,EQE=51.39%,D^(*)=4.42×10^(12)Jones,on/off ratio:~522).
基金financial support from the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.19KJB150020)Basic Research Project(Natural Science Foundation for Young Scholars)of Jiangsu Province,China(No.BK20170489,BK20180916)+1 种基金High Level Introduction of Talent Research Start-up Foundation of YZU(No.137011457)China Postdoctoral Science Foundation(No.2019T120471)。
文摘We reveal here a visible-light promoted phosphorylation of 2-isocyanoaryl thioethers for the first time with concomita nt C(sp3)-S bond cleavage and imidoyl C-S fo rmation.Additionally,this method features the use of 3 mol%organic dye Rose Bengal as the photocatalyst without external transition-metal or peroxide oxidants,and provides a novel and environmentally friendly approach for the preparation of a variety of 2-phosphoryl benzothiazoles in moderate to good yields.
基金supports from the National Key Research and Development Program of China(No.2020YFB1505703)This work was supported by the National Natural Science Foundation of China(Nos.52172299,22175198,51772319,51772320,and 51972331)+3 种基金Z.G.Z would like to acknowledge the support from the External Cooperation Program of the Chinese Academy of Sciences(No.121E32KYSB20190008)Six Talent Peaks Project of Jiangsu Province(No.XCL-170)S.C would like to acknowledge the support from the Youth Innovation Promotion Association,CAS(No.2018356)the Outstanding Youth Fund of Jiangxi(No.20192BCBL23027).
文摘Photo-induced vacancy defects are employed strategically to imbue semiconductors with enhanced performance characteristics for many important applications such as surface-enhanced Raman scattering(SERS)sensing,photocatalysis,and photovoltaic applications.However,the long-term maintenance and use of photo-induced vacancy defects remain elusive,because of their rapid self-healing upon air exposure.In this study,we demonstrate that photo-induced oxygen vacancy(PIVO)defects can be stabilized by the photoexcitation of metal–organic framework(MOF)materials,which is crucial for SERS analysis.The PIVO defects in MOF materials are stable for at least two weeks in the ambient atmosphere,owing to the combination of steric hindrance and electron delocalization around vacancy defects,which significantly contrasts the short lifetime(within minutes)of PIVO defects in metal-oxide semiconductors.With the formation of stable PIVO defects,a prominent SERS enhancement surpassing that of pristine MOFs is achieved,accompanied with a reduced limit of detection by three orders of magnitude.Moreover,the additional SERS enhancement rendered by PIVO defects can be stably retained and is effective for monitoring various small molecules,such as dopamine and bisphenol A.
基金We acknowledge that this work was financially supported by the Scientific and Technological Project in Henan Province(Grant No.212102110139,212102110229)the special project of Xinxiang Science and Technology(Grant No.21ZD003)the Agriculture Research System of MOF and MARA(Grant No.CARS-03).
文摘This study aimed to clarify the synergistic phototactic attraction-repulsion effect formed by the photo-induced approach-avoidance behavior of thrips,construct phototactic attraction-repulsion light control technologies.The phototactic push-pull effects of red light and UV(365 nm),violet(405 nm),green(520 nm),and yellow(560 nm)single light,as well as their pairwise combined light on the behavior of western flower thrips were investigated using an apparatus that measured thrips response.The study also analyzed the influence of light properties on the phototactic attraction-repulsion effects of thrips and the synergistic effects of red light,and the attraction-repulsion regulation mode.The influence factors on the photo-induced attraction-repulsion effect of thrips were also discussed.The results showed that the red light,presenting the push effect,drove thrips to respond to the sensitive light.The synergistic attraction-repulsion effect of red light and singlelight,as well as that of red light and combined light was related to the light intensity.However,the attraction-repulsion synergism did not reflect thrips response effect and approach effect pulled and pushed by red light and single light,red light and combined light.Thrips preference for green-yellow light,and their behavior depended on the degree of UV light,making the attraction-repulsion synergy of red and green light the strongest.When the light intensity increased,the attraction-repulsion synergy of red and yellow light was the strongest.The attraction-repulsion response to red light and single light was related to the spectral attribute of the single light,with that of red lightand UV light being better.The attraction-repulsion response to red light and combined light was related to light intensity.The intensity of combined light made the attraction-repulsion response to red light and the combined UV and violet light be the best,and the brightness of long-short spectrum light rendered red light and the combined UV and yellow light the best.All such light and combinations were remarkably better than that of red light and UV light.Relative to red light and UV light,the use ofred light and combined light provided limited enhancement to the approach effect of thrips;however,under red light and combined light,violet light intensified the approach of thrips to UV light,with yellow light strengthening the approach to green light.Those results provided a scientific basis for the development of light trapping equipment and the adjustment of light control strategies for thrips.
基金supported by the National Natural Science Foundation of China (Grant Nos.U22A6005 and 12074408)the National Key Research and Development Program of China (Grant No.2021YFA1301502)+7 种基金Guangdong Major Scientific Research Project (Grant No.2018KZDXM061)Youth Innovation Promotion Association of CAS (Grant No.2021009)Scientific Instrument Developing Project of the Chinese Academy of Sciences (Grant Nos.YJKYYQ20200055,ZDKYYQ2017000,and 22017BA10)Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant Nos.XDB25000000 and XDB33010100)Beijing Municipal Science and Technology Major Project (Grant No.Z201100001820006)IOP Hundred Talents Program (Grant No.Y9K5051)Postdoctoral Support Program of China (Grant No.2020M670501)the Synergetic Extreme Condition User Facility (SECUF)。
文摘Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump–probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photoinduced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light–free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams.
基金financial supports from the National Natural Science Foundation of China (11974222,12004226,12174229,11904214)Natural Science Foundation of Shandong Province (ZR2022YQ02,ZR2020QA075)+2 种基金Qingchuang Science and Technology Plan of Shandong Province (2021KJ006,2019KJJ014,2019KJJ017)Taishan Scholars Program of Shandong Province (tsqn202306152)China Postdoctoral Science Foundation(2019M662423),Shandong Post-Doctoral Innovation Project (202002021).
文摘Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecular adsorption and controllable molecular orientation.However,it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate.Herein,we demonstrate a graphene oxide(GO)energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity.The Fermi level(Ef)of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate.Experimentally,kelvin probe force microscopy(KPFM)is employed to quantitatively analyze the Ef of GO.Theoretically,the density functional theory calculations are also performed to verify the proposed modulation mechanism.Consequently,the SERS response of probe molecules with different band structures(R6G,CV,MB,PNTP)can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate.This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.
基金supported by National MCF Energy R&D Program of China(2018YFE0306105)National Key R&D Program of China(2020YFA0406104,2020YFA0406101)+6 种基金Innovative Research Group Project of the National Natural Science Foundation of China(51821002)National Natural Science Foundation of China(51725204,21771132,51972216,52041202,51902217)Natural Science Foundation of Jiangsu Province(BK20190041)Key-Area Research and Development Program of GuangDong Province(2019B010933001)Collaborative Innovation Center of Suzhou Nano Science and Technologythe 111 ProjectSuzhou Key Laboratory of Functional Nano and Soft Materials。
文摘Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization,fast migration of charge carriers,efficient surface redox reactions and good electrical conductivity.In this review,we summarize the fabrication methods of CDs and corresponding CD nanocomposites,including the strategies of surface modification and heteroatom doping.The properties of CDs that concerned to the photo-and electro-catalysis are highlighted and detailed corresponding applications are listed.More importantly,as new non-contact detection technologies,transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics,which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts.The development and application of the techniques are reviewed.Finally,we discuss and outline the major challenges and opportunities for future CD-based catalysts,and the needs and expectations for the development of novel characterization technologies.
文摘Ciprofloxacin(CIP), moxifoxacin(MOX) and enrofloxacin(ENR) were selected as typical fluoroquinolones(FQs) to analyze the excitation-enhancing effect and mechanism of solvents on FQs' electron transition based on quantum chemical calculations. The UV spectra of three FQs in gas and five different solvents(water, cyclohexane, dimethylsulfoxide, methanol, acetone) were calculated using Gaussian 09 software. The transition mechanisms of FQs' main electron transitions were analyzed by natural bond orbital(NBO) theory, and the solvent effect on each electron transition was assessed qualitatively and quantitatively by sensitivity analysis and an established index system. The excitation enhancing mechanism of solvent on electron transitions of FQs was analyzed from the view of photo-induced reactions between solvent and FQs molecules. The results show that there are two main transitions located in the spectrum ranges of 300~380 and 240~300 nm for each FQ in any medium, which are assigned as n →π* and π→π* electron transitions, respectively. By comparison, the n →π* transition is more sensitive to solvent because of the energy transfer between solvent molecules and FQs, but the solvent effect on the π→π* transition is stronger than on the n →π* transition. The sequence of affected extent of solvent effect on electron transition was CIP > MOX > ENR, and the sequence of solvent effect was water > DMSO > methanol > acetone > cyclohexane(stronger solvent effect with increasing the dielectric constant of solvent). From the view of photo-induced reactions, the reaction between FQs*T1 and solvent*T1 has the decisive regulatory effect on the n →π* transition of FQs in solvent, and the reaction between FQsS0 and solvent*TI has an enhancing effect on the π→π* transition.
基金The National Natural Science Foundation of China (Grant No. 29774036 and 29904007) and PPLAS Foundation of Chinese Academy of Sciences (Grant No. 01-B-06) are gratefully acknowledged for their financial support of this work.
文摘Electrostatic layer-by-layer self-assembly multilayer films were successfully fabricated from C60-ethylenediamineadduct (C60-EDA) and DNA. Under visible light irradiation, DNA is ready to be cleaved and the films are destroyed.
文摘An efficient pyrene-Schiff base fluorescent sensor PySb was synthesized and evaluated for its fluorescence response to metal ions. Sensor PySb exhibits an “off-on-type” mode with high selectivity to Zn2+ and Al3+ in ethanol (470 nm) and in dimethyl sulfoxide (458 nm) respectively. The originally non-fluorescent PySb, due to photo-induced electron transfer (PET) from imine moiety, is turned on after binding with the cations. The stoichiometric ratio between PySb and Zn2+ is 1:2;moreover, the limit of detection (LOD) and bonding constant were 2.39 × 10-8 M and 2 × 109 M-1 respectively, as obtained from titration experiments.