Enhancement of uorescent radiation is of great importance for applications including biological imaging,high-sensitivity detectors,and integrated light sources.Strong electromagnetic elds can be created around metalli...Enhancement of uorescent radiation is of great importance for applications including biological imaging,high-sensitivity detectors,and integrated light sources.Strong electromagnetic elds can be created around metallic nanoparticles or in gap of nanostructures,where the local state density of radiating mode is then dramatically enhanced.While enhanced uorescent emission has been demonstrated in many metallic nanoparticles and nanoparticle pairs,simultaneous mediation of absorption and emission processes of uorescent emitters remains challenging in metallic nanostructures.Here,we investigate uorescent emission mediated by metal-dielectric-metal fishnet metasurface,in which localized surface plasmon(LSP)and magnetic plasmon polaritons(MPPs)modes are coupled with absorption and emission processes,respectively.For absorption process,coupling of the LSP mode enables spatially-selective excitation of the uorescent emitters by rotating the polarization of the pump laser beam.In addition,the polarization-dependent MPP mode enables manipulation of both polarization and wavelength of the uorescent emission by introducing a rectangular fishnet structure.All the experimental observations are further corroborated by nite-difference time-domain simulations.The structure reported here has great potential for application to color light-emitting devices and nanoscale integrated light sources.展开更多
Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-...Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-destructive advantage, the EEM was applied to characterizing a commercial Fluka humic acid (FHA). The results showed that the EEMs of FHA has several Ex/Em peaks. Ionic strength (0- 0.05 mol/L KClO 4) exerted little effect on the fluorescence properties of FHA, while the concentrations (5-100 mg/L) of FHA and pH (2-12) had significant effects. A red shift in the longer wavelength peak region was observed when the concentrations or pH values increased. The fluorescence intensity increased with increasing pH, but slightly decreased in the case of pH= 5.0. The protonation constants (lgK’ HL) of peak B were calculated to be 3.57 and 3.13, indicating that peak B was due to carboxyl groups. The r (A/B) values range from 0.61 to 2.59. A strong linear relationship between r (A/B) and pH was also observed. This indicates that the fluorescence peaks A and B posses similar inherent fluorescence characteristics.展开更多
The excited-state symmetry-breaking charge transfer (SBCT) dynamics in quadrupolar or octupolar molecules without clear infrared markers is usually hard to be tracked directly. In this work, on the basis of the evolut...The excited-state symmetry-breaking charge transfer (SBCT) dynamics in quadrupolar or octupolar molecules without clear infrared markers is usually hard to be tracked directly. In this work, on the basis of the evolution of instantaneous emission dipole moment obtained by femtosecond transient fluorescence spectroscopy, we presented a real-time characterization of the solvent-induced SBCT dynamics in an octupolar triphenylamine derivative. While the emission dipole moment of the octupolar trimer in weakly polar toluene changes little during the excited-state relaxation, it exhibits a fast reduction in a few picoseconds in strongly polar tetrahydrofuran. In comparison with the uorescence dynamics of dipolar monomer, we deduced that the emitting state of the octupolar trimer in strongly polar solvent, which undergoes solvent-induced structural uctuation, changes from exciton-coupled octupolar to excitation localized dipolar symmetry. In weakly polar solvent, the octupolar symmetry of the trimer is largely preserved during the solvation stabilization.展开更多
We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases...We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.展开更多
Three-dimensional （3D） excitation-emission matrix （EEM） fluorescence spectroscopy is applied to characterize the coal oil. The results show that the 3D fluorescence spectra of coal oil in aqueous solution mainly h...Three-dimensional （3D） excitation-emission matrix （EEM） fluorescence spectroscopy is applied to characterize the coal oil. The results show that the 3D fluorescence spectra of coal oil in aqueous solution mainly have one broad peak. This peak is identified at the excitation/emission wavelengths of 270/290 nm. The relation between the fluorescence intensity and the concentration of coal oil is also studied. When the concentration lies between 2 - 2000 ppm, the relation between the fluorescence intensity and the concentration of coal oil is well linear. The nature of solvents significantly affects the EEM fluorescence of coal oil.展开更多
The aerobic granular sludge was cultivated in a pilot-scale sequencing batch reactor （SBR）, and some of the granules were stored at 8 ℃ for 150 d. Extracellular polymeric substances （EPS） of sludge samples were e...The aerobic granular sludge was cultivated in a pilot-scale sequencing batch reactor （SBR）, and some of the granules were stored at 8 ℃ for 150 d. Extracellular polymeric substances （EPS） of sludge samples were extracted and analyzed during the granulation and storage process. The results show that the contents of protein and EPS increase along with the granulation process, while polysaccharides remain almost unchanged. The content of protein in EPS is almost two-fold larger than that of polysaccharides in granular sludge cultivated with municipal wastewater. Moreover, some of the granules disintegrate during storage, corresponding to the decrease of protein contents in EPS. Three peaks are identified in three-dimensional excitation emission matrix （EEM） fluorescence spectra of the EPS in the aerobic granules. Two peaks （A and B） are attributed to the protein-like fluorophores, and the third （peak C） is related to visible fulvic-like substances. Peak A gradually disappears during storage, while a new peak related to ultraviolet fulvic acid （peak D） is formed. The formation and the stability of aerobic granules are closely dependent on the quantity and composition of EPS proteins. Peak C has no obvious changes during granulation, while the fulvic-like substances present an increase in fluorescence intensities during storage, accompanied with an increase in structural complexity. The fulvie-like substances are also associated with the disintegration of the aerobic granules.展开更多
Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor...Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor analysis （PARAFAC）. Three terrestrial humic-like components （C1, C2 and C3） and one protein-like component （C4） were identified. Based on spatial dis- tributions, as well as relationships with salinity, the following assignments were made. The three humic-like components （CI, C2 and C3） showed conservative mixing behavior and came mainly from riverine input. The protein-like component （C4） was considered a combination of autochthonous production and terrestrial inputs and a biologically labile component. Path analysis of samples from the middle and bottom layers revealed that the causal effects on C1 were -78.46% for salinity, and -21.54% for apparent oxygen utilization （AOU）; those on C2 were -76.43% for salinity, and -23.57% for AOU; those on C3 were -70.49% for salinity, 7.01% for Chl-a, and -22.50% for AOU; those on C4 were -55.54% for salinity, 14.6% for Chl-a, and -29.86% for AOU in middle layer; and those on C4 were -57.37% for salinity, 29.02% for Chl-a, and -13.61% for AOU in bottom layer. Results indicated that CDOM in tile East China Sea was mainly affected by terrestrial inputs, and microbial ac- tivities also played a key role in biogeochemical processes of CDOM. The application of the EEM-PARAFAC model present- ed a unique opportunity to observe compositional changes in CDOM in the East China Sea. In addition, the humification index （HIX） suggested that CDOM from the East China Sea was less stable and stayed shorter in the environment.展开更多
By measuring the emission spectra and the fluorescence lifetime of the ^4I13/2 state of Er^3＋ ions in Gd2SiO5 crystal at different temperatures, the effects of temperature on the spectra and the lifetime of the ^4I13...By measuring the emission spectra and the fluorescence lifetime of the ^4I13/2 state of Er^3＋ ions in Gd2SiO5 crystal at different temperatures, the effects of temperature on the spectra and the lifetime of the ^4I13/2 state are investigated. When the temperature increases, the emission line width for the ^4I13/2 →^4I15/2 transition is broadened, and the main emission lines at 1 596, 1 609, and 1 644 nm shifte toward shorter wavelengths. The measured lifetime of the ^4I13/2 state decreases from 13.2 to 8.4 ms with temperature increase from 13 to 300 K, which is mainly due to the temperature dependence of multiphonon relaxation between the ^4I13/2 and ^4I15/2 states and the changing population distribution among the Stark levels within the ^4I13/2 state. The experimental results imply that low temperature condition is better for the -l.6μm laser output.展开更多
Here,we combined the photon antibunching analysis,fluorescence correlation spectroscopy,and time-domain fluorescence lifetime imaging microscopy(TD-FLIM)to study the emission properties of a representative AIE-lumino...Here,we combined the photon antibunching analysis,fluorescence correlation spectroscopy,and time-domain fluorescence lifetime imaging microscopy(TD-FLIM)to study the emission properties of a representative AIE-luminogen—4,4’-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(N,N-diphenylaniline)(TPA-BT)at the single emitter level in a tetrahydrofuran(THF)/water solution where water is a non-solvent for TPA-BT.Our findings suggest that,at a constant water fraction in the solution,the size of TPA-BT aggregates increases with the TPA-BT concentration;TPA-BT aggregates are not a quantum emitter at room temperature in the solution.Moreover,utilizing TD-FLIM and a gel trapping technique allowed us to study the fluorescence lifetime of individual TPA-BT aggregates.Adding a polar solvent like water does not result in an overall decrease in fluorescence lifetime.Rather,it causes the fluorescence lifetime distribution to become wider,and only some molecules experience a decrease in their fluorescence lifetime.These results could represent a step forward in further understanding the photophysics of AIE-luminogens.展开更多
Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of va...Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of various spectroscopic techniques, mainly including atomic absorption spectrometry (AAS) inductively coupled plasma emission spectrometry (ICP-AES) X-ray fluorescence spectroscopy (XRF) atomic fluorescence spectroscopy (AFS) direct reading spectroscopy (OES) glow discharge emission spectroscopy (GD-OSE) laser-induced breakdown spectroscopy (LIBS), in the formulation of non-ferrous metal standards in China. The AAS method was the most widely used single-element microanalysis method among the non-ferrous metal standards. The ICP-AES method was good at significant advantages in the simultaneous detection of multiple elements. The XRF method was increasingly used in the determination of primary and secondary trace elements due to its simple sample preparation and high efficiency. The AFS was mostly detected by single-element trace analysis. OES GD-OES and LIBS were playing an increasingly important role in the new demand area for non-ferrous metals. This paper discussed matrix elimination, sample digestion, sample preparation, instrument categories and other aspects of some standards, and summarized the advantages of spectral analysis and traditional chemical analysis methods. The new methods of future spectroscopic technology had been illustrated in the process of developing non-ferrous metal standards.展开更多
基金supported by the National Nature Science Foundation of China(No.11674303 and No.11574293)the USTC Center for Micro and Nanoscale Research and Fabrication
文摘Enhancement of uorescent radiation is of great importance for applications including biological imaging,high-sensitivity detectors,and integrated light sources.Strong electromagnetic elds can be created around metallic nanoparticles or in gap of nanostructures,where the local state density of radiating mode is then dramatically enhanced.While enhanced uorescent emission has been demonstrated in many metallic nanoparticles and nanoparticle pairs,simultaneous mediation of absorption and emission processes of uorescent emitters remains challenging in metallic nanostructures.Here,we investigate uorescent emission mediated by metal-dielectric-metal fishnet metasurface,in which localized surface plasmon(LSP)and magnetic plasmon polaritons(MPPs)modes are coupled with absorption and emission processes,respectively.For absorption process,coupling of the LSP mode enables spatially-selective excitation of the uorescent emitters by rotating the polarization of the pump laser beam.In addition,the polarization-dependent MPP mode enables manipulation of both polarization and wavelength of the uorescent emission by introducing a rectangular fishnet structure.All the experimental observations are further corroborated by nite-difference time-domain simulations.The structure reported here has great potential for application to color light-emitting devices and nanoscale integrated light sources.
文摘Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-destructive advantage, the EEM was applied to characterizing a commercial Fluka humic acid (FHA). The results showed that the EEMs of FHA has several Ex/Em peaks. Ionic strength (0- 0.05 mol/L KClO 4) exerted little effect on the fluorescence properties of FHA, while the concentrations (5-100 mg/L) of FHA and pH (2-12) had significant effects. A red shift in the longer wavelength peak region was observed when the concentrations or pH values increased. The fluorescence intensity increased with increasing pH, but slightly decreased in the case of pH= 5.0. The protonation constants (lgK’ HL) of peak B were calculated to be 3.57 and 3.13, indicating that peak B was due to carboxyl groups. The r (A/B) values range from 0.61 to 2.59. A strong linear relationship between r (A/B) and pH was also observed. This indicates that the fluorescence peaks A and B posses similar inherent fluorescence characteristics.
基金supported by the National Natural Science Foundation of China (No.21673252, No.21333012, No.21672211, and No.21773252, No.21827803)the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB12020200)
文摘The excited-state symmetry-breaking charge transfer (SBCT) dynamics in quadrupolar or octupolar molecules without clear infrared markers is usually hard to be tracked directly. In this work, on the basis of the evolution of instantaneous emission dipole moment obtained by femtosecond transient fluorescence spectroscopy, we presented a real-time characterization of the solvent-induced SBCT dynamics in an octupolar triphenylamine derivative. While the emission dipole moment of the octupolar trimer in weakly polar toluene changes little during the excited-state relaxation, it exhibits a fast reduction in a few picoseconds in strongly polar tetrahydrofuran. In comparison with the uorescence dynamics of dipolar monomer, we deduced that the emitting state of the octupolar trimer in strongly polar solvent, which undergoes solvent-induced structural uctuation, changes from exciton-coupled octupolar to excitation localized dipolar symmetry. In weakly polar solvent, the octupolar symmetry of the trimer is largely preserved during the solvation stabilization.
基金Supported by the National Natural Science Foundation of China under Grant No 60378008.
文摘We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.
基金supported by the National"863"Program of China under Grant No.2007AA061502
文摘Three-dimensional （3D） excitation-emission matrix （EEM） fluorescence spectroscopy is applied to characterize the coal oil. The results show that the 3D fluorescence spectra of coal oil in aqueous solution mainly have one broad peak. This peak is identified at the excitation/emission wavelengths of 270/290 nm. The relation between the fluorescence intensity and the concentration of coal oil is also studied. When the concentration lies between 2 - 2000 ppm, the relation between the fluorescence intensity and the concentration of coal oil is well linear. The nature of solvents significantly affects the EEM fluorescence of coal oil.
基金Project(2006AA06Z318) supported by the National High-Tech Research and Development Program of China
文摘The aerobic granular sludge was cultivated in a pilot-scale sequencing batch reactor （SBR）, and some of the granules were stored at 8 ℃ for 150 d. Extracellular polymeric substances （EPS） of sludge samples were extracted and analyzed during the granulation and storage process. The results show that the contents of protein and EPS increase along with the granulation process, while polysaccharides remain almost unchanged. The content of protein in EPS is almost two-fold larger than that of polysaccharides in granular sludge cultivated with municipal wastewater. Moreover, some of the granules disintegrate during storage, corresponding to the decrease of protein contents in EPS. Three peaks are identified in three-dimensional excitation emission matrix （EEM） fluorescence spectra of the EPS in the aerobic granules. Two peaks （A and B） are attributed to the protein-like fluorophores, and the third （peak C） is related to visible fulvic-like substances. Peak A gradually disappears during storage, while a new peak related to ultraviolet fulvic acid （peak D） is formed. The formation and the stability of aerobic granules are closely dependent on the quantity and composition of EPS proteins. Peak C has no obvious changes during granulation, while the fulvic-like substances present an increase in fluorescence intensities during storage, accompanied with an increase in structural complexity. The fulvie-like substances are also associated with the disintegration of the aerobic granules.
基金supported by the National Basic Research Program of China(973 program,2010CB428701)the National Natural Science Foundation of China(41176063)
文摘Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor analysis （PARAFAC）. Three terrestrial humic-like components （C1, C2 and C3） and one protein-like component （C4） were identified. Based on spatial dis- tributions, as well as relationships with salinity, the following assignments were made. The three humic-like components （CI, C2 and C3） showed conservative mixing behavior and came mainly from riverine input. The protein-like component （C4） was considered a combination of autochthonous production and terrestrial inputs and a biologically labile component. Path analysis of samples from the middle and bottom layers revealed that the causal effects on C1 were -78.46% for salinity, and -21.54% for apparent oxygen utilization （AOU）; those on C2 were -76.43% for salinity, and -23.57% for AOU; those on C3 were -70.49% for salinity, 7.01% for Chl-a, and -22.50% for AOU; those on C4 were -55.54% for salinity, 14.6% for Chl-a, and -29.86% for AOU in middle layer; and those on C4 were -57.37% for salinity, 29.02% for Chl-a, and -13.61% for AOU in bottom layer. Results indicated that CDOM in tile East China Sea was mainly affected by terrestrial inputs, and microbial ac- tivities also played a key role in biogeochemical processes of CDOM. The application of the EEM-PARAFAC model present- ed a unique opportunity to observe compositional changes in CDOM in the East China Sea. In addition, the humification index （HIX） suggested that CDOM from the East China Sea was less stable and stayed shorter in the environment.
基金supported by the National Natural Science Foundation of China under Grant No. 90922029
文摘By measuring the emission spectra and the fluorescence lifetime of the ^4I13/2 state of Er^3＋ ions in Gd2SiO5 crystal at different temperatures, the effects of temperature on the spectra and the lifetime of the ^4I13/2 state are investigated. When the temperature increases, the emission line width for the ^4I13/2 →^4I15/2 transition is broadened, and the main emission lines at 1 596, 1 609, and 1 644 nm shifte toward shorter wavelengths. The measured lifetime of the ^4I13/2 state decreases from 13.2 to 8.4 ms with temperature increase from 13 to 300 K, which is mainly due to the temperature dependence of multiphonon relaxation between the ^4I13/2 and ^4I15/2 states and the changing population distribution among the Stark levels within the ^4I13/2 state. The experimental results imply that low temperature condition is better for the -l.6μm laser output.
基金Financial support from the National Natural Science Foundation of China(Nos.22073091 and 21873094)National Key ResearchandDevelopmentProgram ofChina(No.2021YFC2101704)+1 种基金International Science and Technology Cooperation Program of Jilin,China(No.20220508126RC)Key Research Program of Frontier Sciences,Chinese Academy of Sciences(No.ZDBS-LY-SLHO33)is gratefully acknowledged。
文摘Here,we combined the photon antibunching analysis,fluorescence correlation spectroscopy,and time-domain fluorescence lifetime imaging microscopy(TD-FLIM)to study the emission properties of a representative AIE-luminogen—4,4’-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(N,N-diphenylaniline)(TPA-BT)at the single emitter level in a tetrahydrofuran(THF)/water solution where water is a non-solvent for TPA-BT.Our findings suggest that,at a constant water fraction in the solution,the size of TPA-BT aggregates increases with the TPA-BT concentration;TPA-BT aggregates are not a quantum emitter at room temperature in the solution.Moreover,utilizing TD-FLIM and a gel trapping technique allowed us to study the fluorescence lifetime of individual TPA-BT aggregates.Adding a polar solvent like water does not result in an overall decrease in fluorescence lifetime.Rather,it causes the fluorescence lifetime distribution to become wider,and only some molecules experience a decrease in their fluorescence lifetime.These results could represent a step forward in further understanding the photophysics of AIE-luminogens.
文摘Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of various spectroscopic techniques, mainly including atomic absorption spectrometry (AAS) inductively coupled plasma emission spectrometry (ICP-AES) X-ray fluorescence spectroscopy (XRF) atomic fluorescence spectroscopy (AFS) direct reading spectroscopy (OES) glow discharge emission spectroscopy (GD-OSE) laser-induced breakdown spectroscopy (LIBS), in the formulation of non-ferrous metal standards in China. The AAS method was the most widely used single-element microanalysis method among the non-ferrous metal standards. The ICP-AES method was good at significant advantages in the simultaneous detection of multiple elements. The XRF method was increasingly used in the determination of primary and secondary trace elements due to its simple sample preparation and high efficiency. The AFS was mostly detected by single-element trace analysis. OES GD-OES and LIBS were playing an increasingly important role in the new demand area for non-ferrous metals. This paper discussed matrix elimination, sample digestion, sample preparation, instrument categories and other aspects of some standards, and summarized the advantages of spectral analysis and traditional chemical analysis methods. The new methods of future spectroscopic technology had been illustrated in the process of developing non-ferrous metal standards.
