One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated ...One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated a combination of time-resolved LIBS and convolutional neural networks(CNNs) to improve K determination in soil. The time-resolved LIBS contained the information of both wavelength and time dimension. The spectra of wavelength dimension showed the characteristic emission lines of elements, and those of time dimension presented the plasma decay trend. The one-dimensional data of LIBS intensity from the emission line at 766.49 nm were extracted and correlated with the K concentration, showing a poor correlation of R_c^2?=?0.0967, which is caused by the matrix effect of heterogeneous soil. For the wavelength dimension, the two-dimensional data of traditional integrated LIBS were extracted and analyzed by an artificial neural network(ANN), showing R_v^2?=?0.6318 and the root mean square error of validation(RMSEV)?=?0.6234. For the time dimension, the two-dimensional data of time-decay LIBS were extracted and analyzed by ANN, showing R_v^2?=?0.7366 and RMSEV?=?0.7855.These higher determination coefficients reveal that both the non-K emission lines of wavelength dimension and the spectral decay of time dimension could assist in quantitative detection of K.However, due to limited calibration samples, the two-dimensional models presented over-fitting.The three-dimensional data of time-resolved LIBS were analyzed by CNNs, which extracted and integrated the information of both the wavelength and time dimension, showing the R_v^2?=?0.9968 and RMSEV?=?0.0785. CNN analysis of time-resolved LIBS is capable of improving the determination of K in soil.展开更多
It has been proposed previously that the coherent detection of a terahertz（THz） pulse can be achieved based on the time-resolved luminescence quenching. In this paper, we investigate the frequency response range of ...It has been proposed previously that the coherent detection of a terahertz（THz） pulse can be achieved based on the time-resolved luminescence quenching. In this paper, we investigate the frequency response range of this novel detection technology by simulating the motion of carriers in gallium arsenide（GaAs） by the ensemble Monte Carlo method. At room temperature, for a direct-current（DC） voltage of 20 kV/cm applied to the semiconductor（GaAs） and sampling time o140 fs, the luminescence quenching phenomena induced by terahertz pulses with different center frequencies are studied The results show that the quenching efficiency is independent of the THz frequency when the frequency is in a range o0.1 THz–4 THz. However, when the frequency exceeds 4 THz, the efficiency decreases with the increase of frequency Therefore, the frequency response range is 0.1 THz–4 THz. Moreover, when the sampling time is changed to 100 fs the frequency response range is extended to be approximately 0.1 THz–5.6 THz. This study of the frequency-dependen characteristics of the luminescence response to the THz pulse can provide a theoretical basis for the exploration of THz detection technology.展开更多
Quantum materials have attracted a great deal of attention because of their rich landscape of electronic structures,topological phases,strong correlation effects,and exotic orders.These systems provide a fertile platf...Quantum materials have attracted a great deal of attention because of their rich landscape of electronic structures,topological phases,strong correlation effects,and exotic orders.These systems provide a fertile platform for the exploration of novel quantum phenomena and materials applications.Particularly exciting is the exploration of nonequilibrium dynamics in quantum materials,which has significant research and potential application values.Pump-probe techniques play a key role in revealing the dynamics of quantum materials on remarkably short timescales,providing an attractive yet challenging avenue of research.In this context,time-resolved x-ray as an emerging probe exhibits high time resolution,momentum resolution,and substantial momentum coverage.It can reveal unprecedented transient states,distinguish between entangled ordered states,and has a compelling potential to probe ultrafast dynamics in a wide variety of quantum materials.Despite its unique advantages,time-resolved x-ray scattering still faces several technological and methodological challenges.In this review,we highlight recent advances focusing on the use of time-resolved x-ray scattering to probe dynamic processes in quantum materials.We discuss representative examples across structural,electronic,magnetic,and lattice degrees of freedom,and outline promising directions for future research in this rapidly evolving field.展开更多
AIM: To develop the simple, rapid and sensitive dual-label time-resolved fluoroimmunoassay for pepsinogens in human serum.METHODS: Based on two-site sandwich protocol, mono-clonal antibodies (McAbs) against pepsinogen...AIM: To develop the simple, rapid and sensitive dual-label time-resolved fluoroimmunoassay for pepsinogens in human serum.METHODS: Based on two-site sandwich protocol, mono-clonal antibodies (McAbs) against pepsinogen Ⅰ (PG Ⅰ) and PG Ⅱ were co-coated in 96 microtitration wells, and tracer McAbs against PG Ⅰ and PG Ⅱ were labeled with europium (Eu) and samarium (Sm) chelate, respectively. Diluted serum samples of Eu3+- and Sm3+-McAbs were added into microtitration wells simultaneously. After washing, fluorescence of bound Sm3+ and Eu3+ tracers was detected. RESULTS: The detection limit was 0.2 μg/L for PG Ⅰ and 0.05 μg/L for PG Ⅱ. The assay range was 5.0-320.0 μg/Lfor PG Ⅰ and 1.0-55.0 μg/L for PG Ⅱ. The average re-covery rate was 102.7% for PG Ⅰ and 98.8% for PG Ⅱ. Sera from healthy controls and patients with gastric dis-ease were analyzed. The PG detected by dual-label as-say was in good agreement with that detected by single-label assay or by enzyme-linked immunosorbent assay. CONCLUSION: Dual-label assay can provide high-throughput serological screening for gastric diseases.展开更多
A method using the time-resolved fluorescence technology to establish a highly sensitive microcystin-LR （MC-LR） indirect com- petitive immunoassay was proposed in this work. This method was used to monitor the MC-LR...A method using the time-resolved fluorescence technology to establish a highly sensitive microcystin-LR （MC-LR） indirect com- petitive immunoassay was proposed in this work. This method was used to monitor the MC-LR level in source water and treated drinking water from Taihu Lake. Algae in the water samples were removed by eentrifugation, and the MC-LR level was quantified using this method. Testing results showed that the sensitivity of this method was 0.01 μg/L, and the dynamic measuring range was from 0.05 to 2 μg/L. The av- erage recovery was 115%, and the variation （CV） within and between different batches were 7.3% and 9.7%, respectively. Testing results also indicated that this time-resolved fluoroimmunoassay was sensitive and accurate in measuring MC-LR level, especially for quantitative analy- sis MC-LR level in bulk water.展开更多
Transporting information is one of the important functions of photons and is also the essential duty of information science. Here, we realize multiple imaging by detecting photons with changeable wavelengths based on ...Transporting information is one of the important functions of photons and is also the essential duty of information science. Here, we realize multiple imaging by detecting photons with changeable wavelengths based on time-resolved correlation measurements. In our system, information from multiple objects can be transported. During this process, the wavelength of the photons illuminating the objects is different from the wavelength of the photons detected by the detectors. More importantly, the wavelength of the photons that are utilized to record images can also be changed to match the sensitive range of the used detectors. In our experiment, images of the objects are reconstructed clearly by detecting the photons at wavelengths of 650, 810, and 1064 nm, respectively. These properties should have potential applications in information science.展开更多
Ultra-fast x-ray-dynamic experimental subsystem is a facility which can provide femtosecond hard x-ray sources using a femtosecond laser interacting with plasmas. By utilizing these ultra-fast x-rays as a probe, combi...Ultra-fast x-ray-dynamic experimental subsystem is a facility which can provide femtosecond hard x-ray sources using a femtosecond laser interacting with plasmas. By utilizing these ultra-fast x-rays as a probe, combined with a naturally synchronized driver laser as a pump, we can perform dynamic studies on samples with a femtosecond time resolution. This subsystem with a four-dimensional ultra-high spatiotemporal resolution is a powerful tool for studies of the process of photosynthesis, Auger electron effects, lattice vibrations, etc. Compared with conventional x-ray sources based on accelerators, this table-top laser-driven x-ray source has significant advantages in terms of the source size, pulse duration, brightness, flexibility, and economy. It is an effective supplement to the synchrotron light source in the ultrafast detection regime.展开更多
Charge transfer cocrystals,as a promising class of optoelectronic materials,have attracted significant attention due to their strong intermolecular interactions and efficient electronic coupling between donor and acce...Charge transfer cocrystals,as a promising class of optoelectronic materials,have attracted significant attention due to their strong intermolecular interactions and efficient electronic coupling between donor and acceptor molecules.However,a comprehensive understanding of their electronic structure and charge transfer dynamics remains crucial for optimizing their functional properties.In this study,the highly symmetrical polycyclic aromatic hydrocarbon coronene(COR)is selected as the electron donor,the 1,2,4,5-tetracyanobenzene(TCNB),known for its strong electron-accepting capability,is chosen as the electron acceptor.Using the microspacing in-air sublimation method,a highly oriented COR-TCNB organic charge-transfer cocrystal is successfully fabricated.Theoretical calculations,consistent with the experimental spectroscopic analysis,illuminate the electronic structure and charge transfer characteristics of the COR-TCNB cocrystal,and reveal charge redistribution and electron delocalization.The time-resolved fluorescence spectroscopy and transient transmission based on the femtosecond pump-probe method reveal the ultrafast photodynamics and charge transfer exciton formation.The present results exhibited the strong interaction of charge transfer and the existence of charge transfer excitons.This study provides new insights into structure-property relationships in charge transfer cocrystals,offering valuable guidelines for designing functional optoelectronic materials.展开更多
We previously reported that a series of tetraphenylethylene(TPE)-containing all-hydrocarbon conjugated polymers exhibited a specific fluorescence quenching by palladium ions(Pd^(2+)).To understand the quenching mechan...We previously reported that a series of tetraphenylethylene(TPE)-containing all-hydrocarbon conjugated polymers exhibited a specific fluorescence quenching by palladium ions(Pd^(2+)).To understand the quenching mechanism,herein we investigate the quenching behaviors of three TPE derivatives in the presence of Pd^(2+).Each TPE derivative,consisting of TPE unit and terminal vinyl groups,shows an aggregation-induced emission(AIE)and its fluorescence turns off specifically to Pd^(2+).The sensitivity is enhanced with increasing numbers of vinyl groups in the molecules.By time-resolved fluorescence measurement,a dynamic quenching is observed where the fluorescence lifetime is reduced with Pd^(2+).Specifically,the quenching occurs via the electron transfer in the excited states,as suggested by the disappearance of the stimulated emission band in transient absorption spectra.A theoretical calculation on the excited states identifies intermolecular electron transfer from TPE derivatives to Pd,especially for electron-rich TPE derivative.The mechanism can be general for the design of novel AIE active chemosensors.展开更多
Over the past decade the integration of ultrafast spectroscopy with nanoscience has greatly propelled the development of nanoscience, as the key information gleaned from the mechanistic studies with the assistance of ...Over the past decade the integration of ultrafast spectroscopy with nanoscience has greatly propelled the development of nanoscience, as the key information gleaned from the mechanistic studies with the assistance of ultrafast spectroscopy enables a deeper understanding of the structure–function interplay and various interactions involved in the nanosystems.This mini-review presents an overview of the recent advances achieved in our ultrafast spectroscopy laboratory that address the ultrafast dynamics and related mechanisms in several representative nanomaterial complex systems by means of femtosecond time-resolved transient absorption spectroscopy. We attempt to convey instructive, consistent information regarding the important processes, pathways, dynamics, and interactions involved in the nanomaterial complex systems,most of which exhibit excellent performance in photocatalysis.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 61505253)National Key Research and Development Plan of China (Project No. 2016YFD0200601)
文摘One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated a combination of time-resolved LIBS and convolutional neural networks(CNNs) to improve K determination in soil. The time-resolved LIBS contained the information of both wavelength and time dimension. The spectra of wavelength dimension showed the characteristic emission lines of elements, and those of time dimension presented the plasma decay trend. The one-dimensional data of LIBS intensity from the emission line at 766.49 nm were extracted and correlated with the K concentration, showing a poor correlation of R_c^2?=?0.0967, which is caused by the matrix effect of heterogeneous soil. For the wavelength dimension, the two-dimensional data of traditional integrated LIBS were extracted and analyzed by an artificial neural network(ANN), showing R_v^2?=?0.6318 and the root mean square error of validation(RMSEV)?=?0.6234. For the time dimension, the two-dimensional data of time-decay LIBS were extracted and analyzed by ANN, showing R_v^2?=?0.7366 and RMSEV?=?0.7855.These higher determination coefficients reveal that both the non-K emission lines of wavelength dimension and the spectral decay of time dimension could assist in quantitative detection of K.However, due to limited calibration samples, the two-dimensional models presented over-fitting.The three-dimensional data of time-resolved LIBS were analyzed by CNNs, which extracted and integrated the information of both the wavelength and time dimension, showing the R_v^2?=?0.9968 and RMSEV?=?0.0785. CNN analysis of time-resolved LIBS is capable of improving the determination of K in soil.
基金supported by the Wuhan Applied Basic Research Project,China(Grant No.20140101010009)the National Natural Science Foundation of China(Grant Nos.61405063,61475054,11574105,and 61177095)+1 种基金the Hubei Science and Technology Agency Project,China(Grant No.2015BCE052)the Fundamental Research Funds for the Central Universities,China(Grant No.2017KFYXJJ029)
文摘It has been proposed previously that the coherent detection of a terahertz（THz） pulse can be achieved based on the time-resolved luminescence quenching. In this paper, we investigate the frequency response range of this novel detection technology by simulating the motion of carriers in gallium arsenide（GaAs） by the ensemble Monte Carlo method. At room temperature, for a direct-current（DC） voltage of 20 kV/cm applied to the semiconductor（GaAs） and sampling time o140 fs, the luminescence quenching phenomena induced by terahertz pulses with different center frequencies are studied The results show that the quenching efficiency is independent of the THz frequency when the frequency is in a range o0.1 THz–4 THz. However, when the frequency exceeds 4 THz, the efficiency decreases with the increase of frequency Therefore, the frequency response range is 0.1 THz–4 THz. Moreover, when the sampling time is changed to 100 fs the frequency response range is extended to be approximately 0.1 THz–5.6 THz. This study of the frequency-dependen characteristics of the luminescence response to the THz pulse can provide a theoretical basis for the exploration of THz detection technology.
基金the National Key R&D Program of China(Grants Nos.2024YFA1408702 and 2021YFA1401903)Beijing Natural Science Foundation(Grant No.JQ24001)the National Natural Science Foundation of China(Grant No.12374143)。
文摘Quantum materials have attracted a great deal of attention because of their rich landscape of electronic structures,topological phases,strong correlation effects,and exotic orders.These systems provide a fertile platform for the exploration of novel quantum phenomena and materials applications.Particularly exciting is the exploration of nonequilibrium dynamics in quantum materials,which has significant research and potential application values.Pump-probe techniques play a key role in revealing the dynamics of quantum materials on remarkably short timescales,providing an attractive yet challenging avenue of research.In this context,time-resolved x-ray as an emerging probe exhibits high time resolution,momentum resolution,and substantial momentum coverage.It can reveal unprecedented transient states,distinguish between entangled ordered states,and has a compelling potential to probe ultrafast dynamics in a wide variety of quantum materials.Despite its unique advantages,time-resolved x-ray scattering still faces several technological and methodological challenges.In this review,we highlight recent advances focusing on the use of time-resolved x-ray scattering to probe dynamic processes in quantum materials.We discuss representative examples across structural,electronic,magnetic,and lattice degrees of freedom,and outline promising directions for future research in this rapidly evolving field.
基金Supported by The Program of Social Development Fund from Jiangsu Science and Technology Department, No. BS2006015the Program of Health Department of Jiangsu Province, No. H200856
文摘AIM: To develop the simple, rapid and sensitive dual-label time-resolved fluoroimmunoassay for pepsinogens in human serum.METHODS: Based on two-site sandwich protocol, mono-clonal antibodies (McAbs) against pepsinogen Ⅰ (PG Ⅰ) and PG Ⅱ were co-coated in 96 microtitration wells, and tracer McAbs against PG Ⅰ and PG Ⅱ were labeled with europium (Eu) and samarium (Sm) chelate, respectively. Diluted serum samples of Eu3+- and Sm3+-McAbs were added into microtitration wells simultaneously. After washing, fluorescence of bound Sm3+ and Eu3+ tracers was detected. RESULTS: The detection limit was 0.2 μg/L for PG Ⅰ and 0.05 μg/L for PG Ⅱ. The assay range was 5.0-320.0 μg/Lfor PG Ⅰ and 1.0-55.0 μg/L for PG Ⅱ. The average re-covery rate was 102.7% for PG Ⅰ and 98.8% for PG Ⅱ. Sera from healthy controls and patients with gastric dis-ease were analyzed. The PG detected by dual-label as-say was in good agreement with that detected by single-label assay or by enzyme-linked immunosorbent assay. CONCLUSION: Dual-label assay can provide high-throughput serological screening for gastric diseases.
基金Project supported by Foundation of Public Health Department of Jiangsu (HD200865)National High-tech Research and Development Program (863 program) (2008AA10Z415)
文摘A method using the time-resolved fluorescence technology to establish a highly sensitive microcystin-LR （MC-LR） indirect com- petitive immunoassay was proposed in this work. This method was used to monitor the MC-LR level in source water and treated drinking water from Taihu Lake. Algae in the water samples were removed by eentrifugation, and the MC-LR level was quantified using this method. Testing results showed that the sensitivity of this method was 0.01 μg/L, and the dynamic measuring range was from 0.05 to 2 μg/L. The av- erage recovery was 115%, and the variation （CV） within and between different batches were 7.3% and 9.7%, respectively. Testing results also indicated that this time-resolved fluoroimmunoassay was sensitive and accurate in measuring MC-LR level, especially for quantitative analy- sis MC-LR level in bulk water.
基金supported by the National Natural Science Foundation of China(Nos.11534006,11674184,and11374166)the Natural Science Foundation of Tianjin(Nos.16JCZDJC31300 and 13JCZDJC33800)+1 种基金the 111 Project(No.B07013)the Collaborative Innovation Center of Extreme Optics
文摘Transporting information is one of the important functions of photons and is also the essential duty of information science. Here, we realize multiple imaging by detecting photons with changeable wavelengths based on time-resolved correlation measurements. In our system, information from multiple objects can be transported. During this process, the wavelength of the photons illuminating the objects is different from the wavelength of the photons detected by the detectors. More importantly, the wavelength of the photons that are utilized to record images can also be changed to match the sensitive range of the used detectors. In our experiment, images of the objects are reconstructed clearly by detecting the photons at wavelengths of 650, 810, and 1064 nm, respectively. These properties should have potential applications in information science.
基金Project supported by the National Major Science and Technology Infrastructure Construction Project "Synergetic Extreme Condition User Facility",China
文摘Ultra-fast x-ray-dynamic experimental subsystem is a facility which can provide femtosecond hard x-ray sources using a femtosecond laser interacting with plasmas. By utilizing these ultra-fast x-rays as a probe, combined with a naturally synchronized driver laser as a pump, we can perform dynamic studies on samples with a femtosecond time resolution. This subsystem with a four-dimensional ultra-high spatiotemporal resolution is a powerful tool for studies of the process of photosynthesis, Auger electron effects, lattice vibrations, etc. Compared with conventional x-ray sources based on accelerators, this table-top laser-driven x-ray source has significant advantages in terms of the source size, pulse duration, brightness, flexibility, and economy. It is an effective supplement to the synchrotron light source in the ultrafast detection regime.
基金the National Natural Science Foundation of China(No.51875006).
文摘Charge transfer cocrystals,as a promising class of optoelectronic materials,have attracted significant attention due to their strong intermolecular interactions and efficient electronic coupling between donor and acceptor molecules.However,a comprehensive understanding of their electronic structure and charge transfer dynamics remains crucial for optimizing their functional properties.In this study,the highly symmetrical polycyclic aromatic hydrocarbon coronene(COR)is selected as the electron donor,the 1,2,4,5-tetracyanobenzene(TCNB),known for its strong electron-accepting capability,is chosen as the electron acceptor.Using the microspacing in-air sublimation method,a highly oriented COR-TCNB organic charge-transfer cocrystal is successfully fabricated.Theoretical calculations,consistent with the experimental spectroscopic analysis,illuminate the electronic structure and charge transfer characteristics of the COR-TCNB cocrystal,and reveal charge redistribution and electron delocalization.The time-resolved fluorescence spectroscopy and transient transmission based on the femtosecond pump-probe method reveal the ultrafast photodynamics and charge transfer exciton formation.The present results exhibited the strong interaction of charge transfer and the existence of charge transfer excitons.This study provides new insights into structure-property relationships in charge transfer cocrystals,offering valuable guidelines for designing functional optoelectronic materials.
基金the National Natural Science Foundation of China(22075124,21902073)Shenzhen Special Fund(JCYJ20190809115013348)+1 种基金Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)This work is also supported by Center for Computational Science and Engineering of Southern University of Science and Technology.The authors thank Prof.He,T.C.and Mr.Xiao,S.Y.(Shenzhen University)for the measurement of transient absorption spectra.The authors also thank Prof.Liu,Y.and Mr.Feng,Y.(Shenzhen University)for the help during the synthesis.
文摘We previously reported that a series of tetraphenylethylene(TPE)-containing all-hydrocarbon conjugated polymers exhibited a specific fluorescence quenching by palladium ions(Pd^(2+)).To understand the quenching mechanism,herein we investigate the quenching behaviors of three TPE derivatives in the presence of Pd^(2+).Each TPE derivative,consisting of TPE unit and terminal vinyl groups,shows an aggregation-induced emission(AIE)and its fluorescence turns off specifically to Pd^(2+).The sensitivity is enhanced with increasing numbers of vinyl groups in the molecules.By time-resolved fluorescence measurement,a dynamic quenching is observed where the fluorescence lifetime is reduced with Pd^(2+).Specifically,the quenching occurs via the electron transfer in the excited states,as suggested by the disappearance of the stimulated emission band in transient absorption spectra.A theoretical calculation on the excited states identifies intermolecular electron transfer from TPE derivatives to Pd,especially for electron-rich TPE derivative.The mechanism can be general for the design of novel AIE active chemosensors.
基金support from the National Natural Science Foundation of China (21573211 and 21421063)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB01020200)the Fundamental Research Funds for the Central Universities of China (WK2340000063)
文摘Over the past decade the integration of ultrafast spectroscopy with nanoscience has greatly propelled the development of nanoscience, as the key information gleaned from the mechanistic studies with the assistance of ultrafast spectroscopy enables a deeper understanding of the structure–function interplay and various interactions involved in the nanosystems.This mini-review presents an overview of the recent advances achieved in our ultrafast spectroscopy laboratory that address the ultrafast dynamics and related mechanisms in several representative nanomaterial complex systems by means of femtosecond time-resolved transient absorption spectroscopy. We attempt to convey instructive, consistent information regarding the important processes, pathways, dynamics, and interactions involved in the nanomaterial complex systems,most of which exhibit excellent performance in photocatalysis.
