Time-resolved measurement of atomic emission enhancement is performed by using a 500-fs KrF laser pulse incident upon a high density supersonic O2 gas jet, synchronized with an orthogonal ns frequency-doubled Nd:YAG ...Time-resolved measurement of atomic emission enhancement is performed by using a 500-fs KrF laser pulse incident upon a high density supersonic O2 gas jet, synchronized with an orthogonal ns frequency-doubled Nd:YAG laser pulse. The ultra-short pulse serves as an igniter of the gas jet, and the subsequent ns-laser pulse significantly enhances the atomic emission. Analysis shows that the contributions to the enhancement effect are made mainly by the bremsstrahlung radiation and cascade ionization.展开更多
Mechanoresponsive luminescent(MRL)materials have drawn extensive concern due to their potential applications in mechanical sensors,memory chips,and security inks;especially these possessing high emission efficiency.In...Mechanoresponsive luminescent(MRL)materials have drawn extensive concern due to their potential applications in mechanical sensors,memory chips,and security inks;especially these possessing high emission efficiency.In this work,we found trans-stilbene crystal exhibited two different pressure-induced emission enhancement(PIEE)behaviors at different pressure areas.The structural characterizations combined with density functional theory calculation indicate that the first emission enhancement was due to the decrease of nonradiation transition by the weaken of energy exchange process between atoms and lattice.And the second emission enhancement was attributed to the strengthen of C-H...C interactions from the non-planarization comformation.The results regarding the mechanoresponsive behavior of trans-stilbene offered a deep insight into PIEE from the structural point of view,which will facilitate the design of and search for high-performance MRL materials.展开更多
Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhan...Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhancement"strategy for the sensitive and selective detection of spermine.A new pillar[5]arene probe(P1)demonstrated excellent solution/solid dual-state emission properties,and the addition of certain spermine(Spm)resulted in fluorescence enhancement due to the synergy of multiple weak interactions that restricted the free motion of P1 in the P1⊃Spm complex.This mechanism was further confirmed by time-resolved spectroscopy,DFT calculations,and IGM analysis.With its low limit of detection and high selectivity,P1 is a promising tool for measuring spermine in artificial urine samples.展开更多
The mitochondria are essential for tumorigenesis and have been regarded as important targets in cancer chemotherapy.Herein,the mitochondria-targeted platinum(Ⅱ)complexes have been prepared.The introduction of the tri...The mitochondria are essential for tumorigenesis and have been regarded as important targets in cancer chemotherapy.Herein,the mitochondria-targeted platinum(Ⅱ)complexes have been prepared.The introduction of the triazole group with larger steric hindrance through post-click reaction converts the hybridization of carbon from sp to sp^(2),endowing the complexes with an orthogonally oriented ligand with restricted rotation and emission enhancement characteristics.Methylation of the triazolyl ligand has led to platinum(Ⅱ)complexes that can efficiently enter cancer cells and selectively accumulate in mitochondria,leading to significant enhancement in phosphorescence.In vivo anti-cancer investigations have demonstrated their distinct antitumor efficacy in substantial inhibition of tumor growth in breast cancer mice through dissipation of mitochondrial membrane potential,inducing apoptosis of tumor cell with negligibly systemic cytotoxicity.展开更多
Emission enhancement at 2.7 μm is observed in Er^3+/Pr^3+--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient ene...Emission enhancement at 2.7 μm is observed in Er^3+/Pr^3+--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient energy transfer between Er^3+ and Pr^3+; the energy transfer efficiency is as high as 77.4%. The mechanisms of energy transfer are discussed in detail. The calculated emission cross-section of Er^3+/Pr^3+- codoped germanate glass is 8.44× 10 ^-21 cm^2, which suggests that Er^3+/Pr^3+-codoped germanate glass can be used to achieve efficient 2.7-μm emission.展开更多
The multilayered structure thin films(Gd_(2)(MoO_(4))_(3):Ho(Tm)/Yb@Gd_(2)(MoO_(4))_(3):Yb) were prepared through sol-gel and spin-coating method,while the average thinness was nearly 140 nm.We investigated the up-con...The multilayered structure thin films(Gd_(2)(MoO_(4))_(3):Ho(Tm)/Yb@Gd_(2)(MoO_(4))_(3):Yb) were prepared through sol-gel and spin-coating method,while the average thinness was nearly 140 nm.We investigated the up-conversion luminescence of Gd_(2)(MoO_(4))_(3):Ho(Tm)/Yb@Gd_(2)(MoO_(4))_(3):Yb thin films,The results show that the double-layer structured thin films are able to increase the emission intensity.The fluorescence enhancement factors of the luminescence from Gd_(2)(MoO_(4))_(3):Ho/Yb@Gd_(2)(MoO_(4))_(3):Yb thin films,located at540 and 662 nm,reach 7.5 and 4.3,respectively.And the enhancement factors of emissions located at450,475 and 650 nm(Gd_(2)(MoO_(4))_(3):Tm/Yb@Gd_(2)(MoO_(4))_(3):Yb) reach 9,2 and 2,respectively.The considerable enhancement is due to the suppression of surface quenching and energy harvesting via the Yb ions in the outer shell.In addition,the emission color of thin films can be modulated from yellow to blue via tuning the number of Gd_(2)(MoO_(4))_(3):Ho/Yb and Gd_(2)(MoO_(4))_(3):Tm/Yb layers,which provides a feasible strategy to tune the up-conversion emission color.展开更多
Two-dimensional(2D)organic–inorganic halide perovskites present remarkable stability and diversity and are promising alternatives to their three-dimensional(3D)counterparts.The 2D halide perovskite[(HO)(CH_(2))_(2)NH...Two-dimensional(2D)organic–inorganic halide perovskites present remarkable stability and diversity and are promising alternatives to their three-dimensional(3D)counterparts.The 2D halide perovskite[(HO)(CH_(2))_(2)NH_(3)]_(2)PbI_(4)is regarded as a superior moisture-stabile“smooth”perovskite because of distinct hydrogen-bond networks that connect adjacent organic–inorganic layers.展开更多
Charged metal-organic cages generally produce aggregates with various morphologies and different properties through the multiple supramolecular interactions in solution. Herein, a luminescent hexahedral metal-organic ...Charged metal-organic cages generally produce aggregates with various morphologies and different properties through the multiple supramolecular interactions in solution. Herein, a luminescent hexahedral metal-organic cage containing pyrene chromophores is successfully constructed through coordination-driven subcomponent self-assembly. The cage exhibits novel spontaneous aggregation in a dilute solution and time-dependent luminescence enhancement behavior during the subsequent incubation process. Dynamic light scatter(DLS) and transmission electron microscopy(TEM) results prove that the metalorganic cages can form blackberry-like aggregates in methanol dilute solution. Unexpectedly, the luminescent intensity of this system shows a linear increase with the extension of the incubation time in methanol, and this process is also reflected in the change in the quantum yield of the system(2% to over 80% after 5 days incubation time). Ultraviolet-visible(UV-vis),1 H nuclear magnetic resonance(1 H NMR) and mass spectra show that metal-organic cages can stably exist in dilute solution. Timedepended DLS and TEM data reveal that the aggregates of metal-organic cages are gradually changed from the dense state to the loose one, which may involve the transition of the system from an energy unstable state to a stable one, probably leading to the unusual time-dependent luminescent property. This unique time-dependent luminescent cage aggregate can be potentially applied as a “supramolecular time meter”.展开更多
Organic micro/nanocrystals with polymorphic tailorability and perfect platform to modulate decode the complex relationship among molecular structures,supramolecular/noncovalent interactions,aggregates and exciton beha...Organic micro/nanocrystals with polymorphic tailorability and perfect platform to modulate decode the complex relationship among molecular structures,supramolecular/noncovalent interactions,aggregates and exciton behaviors.Herein,we precisely tune the polymorphic two-dimensional organic nanosheets(2DONs)of cyano-spirocyclic aromatic hydrocarbon(2'-CN-SFX),where the crystal growth processes are dominated by precursor concentration.The low concentration(ca.2 mmol/L)affords the rhombus-like nanosheets with monoclinic P21/c space group,in which molecules adopt antiparallel and slipped stacking mode.In contrast,the high concentration(ca.4 mmol/L)favors herringbone-like molecular packing pattern and then generates shuttle-like nanosheets with monoclinic C2/c space group.Both above polymorphic nanosheets exhibit unprecedented crystallization-induced emission en-hancement(CIEE)feature that increases the photoluminescence quantum yields(PLQYs)from 16%in solution,21%in amorphous film to 37%-39%in crystalline states.This result will offer promising opportunities for nanophotonics and organic intelligent semi-conductors.展开更多
Aggregation-induced emission enhancement and aggregation-induced chirality inversion are two individ-ual phenomena for the enantiomerically pure organic dyes in the aggregates.Herein we reported for the first time tha...Aggregation-induced emission enhancement and aggregation-induced chirality inversion are two individ-ual phenomena for the enantiomerically pure organic dyes in the aggregates.Herein we reported for the first time that these two interesting phenomena could be observed simultaneously in the aggregated states of enantiomerically pure S/R-1,1?-binaphthol annulated perylene diimides,in which two perylene diimides moieties were bridged by S/R-1,1?-binaphthol(BINOL)at the bay positions.Owing to the rotat-able C2 axes between two naphthol annulated perylene diimides moieties,both of them display intrinsic behaviors of aggregation-induced emission enhancements.At the same time,due to the steric hindrances in the imide and methoxy positions,the neighboring twoπ-systems of these two unique polycyclic aro-matic imides in poor solvents are preferable to adopt a cross-stacking mode and thus form helical X-aggregates of opposite chirality(M/P)with chirality inversion characteristics in their circular dichroism and circularly polarized luminescence spectroscopic studies.展开更多
The perturbation in the magnetic field generated by the rotation or oscillation of magnetic domains in magnetic materials can emit low-frequency electromagnetic waves,which are expected to be used in low-frequency com...The perturbation in the magnetic field generated by the rotation or oscillation of magnetic domains in magnetic materials can emit low-frequency electromagnetic waves,which are expected to be used in low-frequency communications.However,the magnetic emission intensity,defined by the perturbation ability,of current commercially applied amorphous alloys,such as Metglas,cannot meet the application requirements for low-frequency antennas due to the domain motion energy loss.Herein,a multi-phase Metglas amorphous alloy was constructed by incorporatingα-Fe nanocrystals using rapid annealing to manipulate the domain movement.It was found that 3.89 times higher magnetic emission intensity is obtained compared to the pristine due to the synergism of the deformation and displacement mechanisms.Moreover,the low-frequency magnetic emission performance verification was carried out by preparing magnetoelectric composites as the antenna vibrator by assembling the alloy and macro piezoelectric fiber composites(MFC).Enhancements of magnetic emission intensity are found at 93.3%and 49.2%at the first and second harmonic frequencies compared with the unmodified alloy vibrator.Therefore,the approach leads to the development of high-performance communication with a novel standard for evaluation.展开更多
In this study, a femtosecond laser was focused to ablate brass target and generate plasma emission in air. The influence of lens to sample distance(LTSD) on spectral emission of brass plasma under linearly and circula...In this study, a femtosecond laser was focused to ablate brass target and generate plasma emission in air. The influence of lens to sample distance(LTSD) on spectral emission of brass plasma under linearly and circularly polarized pulses with different pulse energies was investigated. The results indicated that the position with the strongest spectral emission moved toward focusing lens with increasing the energy. At the same laser energy, the line emission under circularly polarized pulse was stronger compared with linearly polarized pulse for different LTSDs. Next, electron temperature and density of the plasma were obtained with Cu(Ⅰ) lines,indicating that the electron temperature and density under circularly polarized pulse were higher compared to that under linearly polarized pulse. Therefore, changing the laser polarization is a simple and effective way to improve the spectral emission intensity of femtosecond laserinduced plasma.展开更多
Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond (MCD) films. Its electrical field...Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond (MCD) films. Its electrical field emission behavior can be turned on at Eo = 2.6 V/μm, attaining a current density of 19.5μA/cm2 at an applied field of 3.5 V/#m. Field emission scanning electron microscopy combined with Raman and x-ray photoelectron mi- croscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films, forming conduction channels for electron transportation.展开更多
The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor ...The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor luminescence performance limits its application in light-emitting diodes(LEDs)and other fields.Herein,for the first time,an Ag^(+)ion doping strategy was proposed to greatly improve the emission performance of Cs_(4)CdBi_(2)Cl_(12) synthesized by hydrothermal method.Density functional theory calculations combined with experimental results evidence that the weak orange emission from Cs_(4)CdBi_(2)Cl_(12) is attributed to the phonon scattering and energy level crossing due to the large lattice distortion under excited states.Fortunately,Ag^(+)ion doping breaks the intrinsic crystal field environment of Cs_(4)CdBi_(2)Cl_(12),suppresses the crossover between ground and excited states,and reduces the energy loss in the form of nonradiative recombination.At a critical doping amount of 0.8%,the emission intensity of Cs_(4)CdBi_(2)Cl_(12):Ag^(+)reaches the maximum,about eight times that of the pristine sample.Moreover,the doped Cs_(4)CdBi_(2)Cl_(12) still maintains excellent stability against heat,ultraviolet irradiation,and environmental oxygen/moisture.The above advantages make it possible for this material to be used as solid-state phosphors for white LEDs applications,and the Commission International de I’Eclairage color coordinates of(0.31,0.34)and high color rendering index of 90.6 were achieved.More importantly,the white LED demonstrates remarkable operation stability in air ambient,showing almost no emission decay after a long working time for 48 h.We believe that this study puts forward an effective ion-doping strategy for emission enhancement of vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),highlighting its great potential as efficient emitter compatible for practical applications.展开更多
Spectral intensity,electron temperature and density of laser-induced plasma(LIP) are important parameters for affecting sensitivity of laser-induced breakdown spectroscopy(LIBS).Increasing target temperature is an eas...Spectral intensity,electron temperature and density of laser-induced plasma(LIP) are important parameters for affecting sensitivity of laser-induced breakdown spectroscopy(LIBS).Increasing target temperature is an easy and feasible method to improve the sensitivity.In this paper,a brass target in a temperature range from 25℃ to 200℃ was ablated to generate the LIP using femtosecond pulse.Time-resolved spectral emission of the femtosecond LIBS was measured under different target temperatures.The results showed that,compared with the experimental condition of 25℃,the spectral intensity of the femtosecond LIP was enhanced with more temperature target.In addition,the electron temperature and density were calculated by Boltzmann equation and Stark broadening,indicating that the changes in the electron temperature and density of femtosecond LIP with the increase of the target temperature were different from each other.By increasing the target temperature,the electron temperature increased while the electron density decreased.Therefore,in femtosecond LIBS,a hightemperature and low-density plasma with high emission can be generated by increasing the target temperature.The increase in the target temperature can improve the resolution and sensitivity of femtosecond LIBS.展开更多
The development of organic materials with white-light emission and thermally activated delayed fluorescence(TADF)properties in the solid state remain a challenge.Herein,a series of white-light-emitting organic luminog...The development of organic materials with white-light emission and thermally activated delayed fluorescence(TADF)properties in the solid state remain a challenge.Herein,a series of white-light-emitting organic luminogens have been developed and are found to show aggregation-induced delayed fluorescence(AIDF)characteristics.The AIDF emitters present dual-emission consisted of prompt fluorescence and TADF in the crystalline state.Their white-light emissions can be easily tuned by altering the chemical structure and connecting position of the heterocyclic aromatic substituent.Under the stimuli of mechanical force and solvent vapor,the compounds exhibit remarkable and reversible mechanochromism,in which their emission colors are switchable between white and yellow.Upon grinding,they also display linearly tunable luminescence colors,as well as force-induced TADF enhancement,which may be associated with the more compact molecular packing and the restriction of intramolecular motions.The results from time-resolved emission scanning and theoretical calculation suggest that the dual-emission of the AIDF luminogens likely results from the twisted intramolecular charge transfer transitions of the molecules,and the reversible mechanochromism properties probably stem from the interconversion of the quasi-axial and the quasi-equatorial conformations.展开更多
Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to produce plasmas on aluminum-based alloy in single- and collinear double-pulse laser induced breakdown spectroscopy (LIBS). Time resolved tech...Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to produce plasmas on aluminum-based alloy in single- and collinear double-pulse laser induced breakdown spectroscopy (LIBS). Time resolved technique was used for detecting emission sig- nal by spectrometer equipped with ICCD detector. The intensity calibration of spectral response was performed by using deuterium and tungsten halogen lamps. Time evolution of the plasma temperature and electron number density was investigated in single- and collinear double-pulse experiments. Based on the investigation of plasma parameters, the emission signal enhancement mechanism was discussed qualitatively.展开更多
Stimulated emission can be controlled by a material molecular energy band and the intensity of a pump laser, which can provide some population inversion and promote ground electron transition, respectively. We use a m...Stimulated emission can be controlled by a material molecular energy band and the intensity of a pump laser, which can provide some population inversion and promote ground electron transition, respectively. We use a metallic optofluidic resonator to enhance stimulated emission intensity. The quality factor Q and the spontaneous emission coupling factor β of the metallic optofluidic resonator are discussed in detail to explain the enhancement mechanism. Experimental data demonstrate that the operated emission from rhodamin 6G solution can be observed due to the enhancement of stimulated emission from the optofluidic resonator.展开更多
Otoacoustic emissions (OAEs) has been considered as an excellent objective tool in clinics for diagnosing hearing loss. The signal-to-noise ratio (SNR) and correlation coefficient of OAEs are very important for the pu...Otoacoustic emissions (OAEs) has been considered as an excellent objective tool in clinics for diagnosing hearing loss. The signal-to-noise ratio (SNR) and correlation coefficient of OAEs are very important for the purpose of diagnosis. An adaptive signal enhancer (ASE) based on the Least Mean Square (LMS) algorithm is presented to detect transient evoked OAEs (TEOAEs). The TEOAEs detection results from 106 ears show that ASE reaches better estimation of TEOAEs than a conventional ensemble averaging (EA) technique. With the ASE, the improvement of SNR was increased faster than that with the EA and the number of sweeps required can be markedly reduced. The detection time with ASE could be shortened by about 50% in comparison with that of EA.展开更多
We studied experimentally the effect of microwaves (MWs) on the enhancement of plasma emission achieved by laser-induced breakdown spectroscopy (LIBS). A laser plasma was generated on a calcium oxide pellet by a N...We studied experimentally the effect of microwaves (MWs) on the enhancement of plasma emission achieved by laser-induced breakdown spectroscopy (LIBS). A laser plasma was generated on a calcium oxide pellet by a Nd:YAG laser (5 m J, 532 nm, 8 ns) in reduced-pressure argon surrounding gas. A MW radiation (400 W) was injected into the laser plasma via a loop antenna placed immediately above the laser plasma to enhance the plasma emission. The results confirmed that when tile electromagnetic field was introduced into the laser plasma region by the MWs, the lifetime of the plasma was extended from 50 to 500 μs, similar to the MW duration. Furthermore, the plasma temperature and electron density increased to approximately 10900 K and 1.5×10^18 cm^-3, respectively and the size of the plasma emission was extended to 15 mm in diameter. As a result, the emission intensity of Ca lines obtained using LIBS with MWs was enhanced by approximately 200 times compared to the case of LIBS without MWs.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10474081).
文摘Time-resolved measurement of atomic emission enhancement is performed by using a 500-fs KrF laser pulse incident upon a high density supersonic O2 gas jet, synchronized with an orthogonal ns frequency-doubled Nd:YAG laser pulse. The ultra-short pulse serves as an igniter of the gas jet, and the subsequent ns-laser pulse significantly enhances the atomic emission. Analysis shows that the contributions to the enhancement effect are made mainly by the bremsstrahlung radiation and cascade ionization.
基金the National Natural Science Foundation of China(Grant Nos.21725304,11774120,and 11904010)the Chang Jiang Scholars Program of China(Grant No.T2016051)+2 种基金Changbai Mountain Scholars Program(Grant No.2013007)the Science and Technology Innovation Program of Shanxi Province,China(Grant Nos.2020L0540 and 2020L0544)Scientific Research Fund of XinZhou Teachers University(Grant No.2019KY04).
文摘Mechanoresponsive luminescent(MRL)materials have drawn extensive concern due to their potential applications in mechanical sensors,memory chips,and security inks;especially these possessing high emission efficiency.In this work,we found trans-stilbene crystal exhibited two different pressure-induced emission enhancement(PIEE)behaviors at different pressure areas.The structural characterizations combined with density functional theory calculation indicate that the first emission enhancement was due to the decrease of nonradiation transition by the weaken of energy exchange process between atoms and lattice.And the second emission enhancement was attributed to the strengthen of C-H...C interactions from the non-planarization comformation.The results regarding the mechanoresponsive behavior of trans-stilbene offered a deep insight into PIEE from the structural point of view,which will facilitate the design of and search for high-performance MRL materials.
基金the National Natural Science Foundation of China(Nos.22071066,22071065)the National Key Research and Development Program of China(No.2016YFA0602900)+1 种基金the Guangdong Natural Science Foundation,China(No.2018B030311008)the Guangzhou Science and Technology Project,China(No.202102020802).
文摘Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhancement"strategy for the sensitive and selective detection of spermine.A new pillar[5]arene probe(P1)demonstrated excellent solution/solid dual-state emission properties,and the addition of certain spermine(Spm)resulted in fluorescence enhancement due to the synergy of multiple weak interactions that restricted the free motion of P1 in the P1⊃Spm complex.This mechanism was further confirmed by time-resolved spectroscopy,DFT calculations,and IGM analysis.With its low limit of detection and high selectivity,P1 is a promising tool for measuring spermine in artificial urine samples.
基金supported by Zhejiang Provincial Natural Science Foundation of China(LR22B010001,LQ23B010001)the National Natural Science Foundation of China(22201057,21871297)+7 种基金the General Research Fund(GRF)grant from the Research Grants Council of the Hong Kong Special Administrative Region,People’s Republic of China(HKU17303421)the Collaborative Research Fund(CRF)(C7075-21G)Hangzhou Normal University(2021QDL001,2021QDL065)the West Lake Scholar Plan,the Hangzhou Leading Innovation and Entrepreneurship Team Project(TD2022001)the CAS-Croucher Funding Scheme for Joint Laboratory on Molecular Functional Materials for Electronics,Switching and Sensingsupport from Sun Yat-Sen UniversityThe University of Hong Kongthe Innovation Technology Commission to the State Key Laboratory of Synthetic Chemistry。
文摘The mitochondria are essential for tumorigenesis and have been regarded as important targets in cancer chemotherapy.Herein,the mitochondria-targeted platinum(Ⅱ)complexes have been prepared.The introduction of the triazole group with larger steric hindrance through post-click reaction converts the hybridization of carbon from sp to sp^(2),endowing the complexes with an orthogonally oriented ligand with restricted rotation and emission enhancement characteristics.Methylation of the triazolyl ligand has led to platinum(Ⅱ)complexes that can efficiently enter cancer cells and selectively accumulate in mitochondria,leading to significant enhancement in phosphorescence.In vivo anti-cancer investigations have demonstrated their distinct antitumor efficacy in substantial inhibition of tumor growth in breast cancer mice through dissipation of mitochondrial membrane potential,inducing apoptosis of tumor cell with negligibly systemic cytotoxicity.
基金supported by the National Natural Science Foundation of China(Nos.51172252 and 61177083)
文摘Emission enhancement at 2.7 μm is observed in Er^3+/Pr^3+--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient energy transfer between Er^3+ and Pr^3+; the energy transfer efficiency is as high as 77.4%. The mechanisms of energy transfer are discussed in detail. The calculated emission cross-section of Er^3+/Pr^3+- codoped germanate glass is 8.44× 10 ^-21 cm^2, which suggests that Er^3+/Pr^3+-codoped germanate glass can be used to achieve efficient 2.7-μm emission.
基金Project supported by the National Natural Science Foundation of China(11474078)。
文摘The multilayered structure thin films(Gd_(2)(MoO_(4))_(3):Ho(Tm)/Yb@Gd_(2)(MoO_(4))_(3):Yb) were prepared through sol-gel and spin-coating method,while the average thinness was nearly 140 nm.We investigated the up-conversion luminescence of Gd_(2)(MoO_(4))_(3):Ho(Tm)/Yb@Gd_(2)(MoO_(4))_(3):Yb thin films,The results show that the double-layer structured thin films are able to increase the emission intensity.The fluorescence enhancement factors of the luminescence from Gd_(2)(MoO_(4))_(3):Ho/Yb@Gd_(2)(MoO_(4))_(3):Yb thin films,located at540 and 662 nm,reach 7.5 and 4.3,respectively.And the enhancement factors of emissions located at450,475 and 650 nm(Gd_(2)(MoO_(4))_(3):Tm/Yb@Gd_(2)(MoO_(4))_(3):Yb) reach 9,2 and 2,respectively.The considerable enhancement is due to the suppression of surface quenching and energy harvesting via the Yb ions in the outer shell.In addition,the emission color of thin films can be modulated from yellow to blue via tuning the number of Gd_(2)(MoO_(4))_(3):Ho/Yb and Gd_(2)(MoO_(4))_(3):Tm/Yb layers,which provides a feasible strategy to tune the up-conversion emission color.
基金supported by the National Science Foundation of China(NSFC)(nos.21725304 and 11774120)the Chang Jiang Scholars Program of China(no.T2016051).Angle-dispersive XRD measurement was performed on the BL15U1 at the Shanghai Synchrotron Radiation Facility(SSRF).
文摘Two-dimensional(2D)organic–inorganic halide perovskites present remarkable stability and diversity and are promising alternatives to their three-dimensional(3D)counterparts.The 2D halide perovskite[(HO)(CH_(2))_(2)NH_(3)]_(2)PbI_(4)is regarded as a superior moisture-stabile“smooth”perovskite because of distinct hydrogen-bond networks that connect adjacent organic–inorganic layers.
基金supported by the Guangdong Major Project of Basic and Applied Research (2019B030302009)the National Natural Science Foundation of China (22171106, 21731002, 21975104,21871172)+1 种基金the Guangzhou Science and Technology Program(202002030411)Jinan University。
文摘Charged metal-organic cages generally produce aggregates with various morphologies and different properties through the multiple supramolecular interactions in solution. Herein, a luminescent hexahedral metal-organic cage containing pyrene chromophores is successfully constructed through coordination-driven subcomponent self-assembly. The cage exhibits novel spontaneous aggregation in a dilute solution and time-dependent luminescence enhancement behavior during the subsequent incubation process. Dynamic light scatter(DLS) and transmission electron microscopy(TEM) results prove that the metalorganic cages can form blackberry-like aggregates in methanol dilute solution. Unexpectedly, the luminescent intensity of this system shows a linear increase with the extension of the incubation time in methanol, and this process is also reflected in the change in the quantum yield of the system(2% to over 80% after 5 days incubation time). Ultraviolet-visible(UV-vis),1 H nuclear magnetic resonance(1 H NMR) and mass spectra show that metal-organic cages can stably exist in dilute solution. Timedepended DLS and TEM data reveal that the aggregates of metal-organic cages are gradually changed from the dense state to the loose one, which may involve the transition of the system from an energy unstable state to a stable one, probably leading to the unusual time-dependent luminescent property. This unique time-dependent luminescent cage aggregate can be potentially applied as a “supramolecular time meter”.
基金supported by the National Natural Science Foundation of China(Nos.61604081,61605090,U1301243)the Natural Science Foundation of the Jiangsu Higher Education Institutions(No.16KJB430023)+6 种基金the Doctoral Fund of Ministry of Education of China(No.20133223110007)the Excellent Science and Technology Innovation Team of Jiangsu Higher Education Institutions(2013)the Natural Science Foundation of jiangsu Province(No.BM2012010)the Six Talent Peaks Project of Jiangsu Province(No.XCL-CXTD-009)the Project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,PAPD(No.YX03002)NUPTSF(Nos.NY215055,NY215061)the Program for Postgraduates Research Innovation in University of Jiangsu Province(No.KYCX200744)。
文摘Organic micro/nanocrystals with polymorphic tailorability and perfect platform to modulate decode the complex relationship among molecular structures,supramolecular/noncovalent interactions,aggregates and exciton behaviors.Herein,we precisely tune the polymorphic two-dimensional organic nanosheets(2DONs)of cyano-spirocyclic aromatic hydrocarbon(2'-CN-SFX),where the crystal growth processes are dominated by precursor concentration.The low concentration(ca.2 mmol/L)affords the rhombus-like nanosheets with monoclinic P21/c space group,in which molecules adopt antiparallel and slipped stacking mode.In contrast,the high concentration(ca.4 mmol/L)favors herringbone-like molecular packing pattern and then generates shuttle-like nanosheets with monoclinic C2/c space group.Both above polymorphic nanosheets exhibit unprecedented crystallization-induced emission en-hancement(CIEE)feature that increases the photoluminescence quantum yields(PLQYs)from 16%in solution,21%in amorphous film to 37%-39%in crystalline states.This result will offer promising opportunities for nanophotonics and organic intelligent semi-conductors.
基金supported by the National Natural Sci-ence Foundation of China(No.21971041)Natural Science Foundation of Fujian Province(No.2020J01447).
文摘Aggregation-induced emission enhancement and aggregation-induced chirality inversion are two individ-ual phenomena for the enantiomerically pure organic dyes in the aggregates.Herein we reported for the first time that these two interesting phenomena could be observed simultaneously in the aggregated states of enantiomerically pure S/R-1,1?-binaphthol annulated perylene diimides,in which two perylene diimides moieties were bridged by S/R-1,1?-binaphthol(BINOL)at the bay positions.Owing to the rotat-able C2 axes between two naphthol annulated perylene diimides moieties,both of them display intrinsic behaviors of aggregation-induced emission enhancements.At the same time,due to the steric hindrances in the imide and methoxy positions,the neighboring twoπ-systems of these two unique polycyclic aro-matic imides in poor solvents are preferable to adopt a cross-stacking mode and thus form helical X-aggregates of opposite chirality(M/P)with chirality inversion characteristics in their circular dichroism and circularly polarized luminescence spectroscopic studies.
基金supported by the Key Research and Development Program of Hubei Province(No.2021BAA214)the Open Fund of Sanya Science and Education Innovation Park of Wuhan University of Technology(Nos.2021KF0022,2021KF0013,and 2020KF0026)+2 种基金Independent Innovation Projects of the Hubei Longzhong Laboratory(Nos.2022ZZ-34 and 2022ZZ-35)the National Science Fund for Distinguished Young Scholars of Hubei Province(No.201CFA067)the National innovation and entrepreneurship training program for college students(Nos.202310497010 and S202310497026).
文摘The perturbation in the magnetic field generated by the rotation or oscillation of magnetic domains in magnetic materials can emit low-frequency electromagnetic waves,which are expected to be used in low-frequency communications.However,the magnetic emission intensity,defined by the perturbation ability,of current commercially applied amorphous alloys,such as Metglas,cannot meet the application requirements for low-frequency antennas due to the domain motion energy loss.Herein,a multi-phase Metglas amorphous alloy was constructed by incorporatingα-Fe nanocrystals using rapid annealing to manipulate the domain movement.It was found that 3.89 times higher magnetic emission intensity is obtained compared to the pristine due to the synergism of the deformation and displacement mechanisms.Moreover,the low-frequency magnetic emission performance verification was carried out by preparing magnetoelectric composites as the antenna vibrator by assembling the alloy and macro piezoelectric fiber composites(MFC).Enhancements of magnetic emission intensity are found at 93.3%and 49.2%at the first and second harmonic frequencies compared with the unmodified alloy vibrator.Therefore,the approach leads to the development of high-performance communication with a novel standard for evaluation.
基金support by National Natural Science Foundation of China(Nos.11674128,11674124 and 11974138)Scientific and Technological Research Project of the Education Department of Jilin Province in China(No.JJKH20200937KJ).
文摘In this study, a femtosecond laser was focused to ablate brass target and generate plasma emission in air. The influence of lens to sample distance(LTSD) on spectral emission of brass plasma under linearly and circularly polarized pulses with different pulse energies was investigated. The results indicated that the position with the strongest spectral emission moved toward focusing lens with increasing the energy. At the same laser energy, the line emission under circularly polarized pulse was stronger compared with linearly polarized pulse for different LTSDs. Next, electron temperature and density of the plasma were obtained with Cu(Ⅰ) lines,indicating that the electron temperature and density under circularly polarized pulse were higher compared to that under linearly polarized pulse. Therefore, changing the laser polarization is a simple and effective way to improve the spectral emission intensity of femtosecond laserinduced plasma.
基金Supported by the National Natural Science Foundation of China under Grant No 11405114the Natural Science Foundation of Shanxi Province under Grant No 2015021065
文摘Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond (MCD) films. Its electrical field emission behavior can be turned on at Eo = 2.6 V/μm, attaining a current density of 19.5μA/cm2 at an applied field of 3.5 V/#m. Field emission scanning electron microscopy combined with Raman and x-ray photoelectron mi- croscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films, forming conduction channels for electron transportation.
基金support from the National Key R&D Program of China(No.2022YFB2803900)the National Natural Science Foundation of China(Nos.12074347,12004346,12204426,and 61935009)+1 种基金Science Foundation for Distinguished Young Scholars of Henan Province(No.212300410019)the Support Program for Scientific and Technological Innovation Teams of Higher Education in Henan Province(No.231RTSTHN012).
文摘The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor luminescence performance limits its application in light-emitting diodes(LEDs)and other fields.Herein,for the first time,an Ag^(+)ion doping strategy was proposed to greatly improve the emission performance of Cs_(4)CdBi_(2)Cl_(12) synthesized by hydrothermal method.Density functional theory calculations combined with experimental results evidence that the weak orange emission from Cs_(4)CdBi_(2)Cl_(12) is attributed to the phonon scattering and energy level crossing due to the large lattice distortion under excited states.Fortunately,Ag^(+)ion doping breaks the intrinsic crystal field environment of Cs_(4)CdBi_(2)Cl_(12),suppresses the crossover between ground and excited states,and reduces the energy loss in the form of nonradiative recombination.At a critical doping amount of 0.8%,the emission intensity of Cs_(4)CdBi_(2)Cl_(12):Ag^(+)reaches the maximum,about eight times that of the pristine sample.Moreover,the doped Cs_(4)CdBi_(2)Cl_(12) still maintains excellent stability against heat,ultraviolet irradiation,and environmental oxygen/moisture.The above advantages make it possible for this material to be used as solid-state phosphors for white LEDs applications,and the Commission International de I’Eclairage color coordinates of(0.31,0.34)and high color rendering index of 90.6 were achieved.More importantly,the white LED demonstrates remarkable operation stability in air ambient,showing almost no emission decay after a long working time for 48 h.We believe that this study puts forward an effective ion-doping strategy for emission enhancement of vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),highlighting its great potential as efficient emitter compatible for practical applications.
基金support by National Natural Science Foundation of China (Nos. 11674128, 11674124 and 11974138)the Jilin Province Scientific and Technological Development Program, China (No. 20170101063JC)。
文摘Spectral intensity,electron temperature and density of laser-induced plasma(LIP) are important parameters for affecting sensitivity of laser-induced breakdown spectroscopy(LIBS).Increasing target temperature is an easy and feasible method to improve the sensitivity.In this paper,a brass target in a temperature range from 25℃ to 200℃ was ablated to generate the LIP using femtosecond pulse.Time-resolved spectral emission of the femtosecond LIBS was measured under different target temperatures.The results showed that,compared with the experimental condition of 25℃,the spectral intensity of the femtosecond LIP was enhanced with more temperature target.In addition,the electron temperature and density were calculated by Boltzmann equation and Stark broadening,indicating that the changes in the electron temperature and density of femtosecond LIP with the increase of the target temperature were different from each other.By increasing the target temperature,the electron temperature increased while the electron density decreased.Therefore,in femtosecond LIBS,a hightemperature and low-density plasma with high emission can be generated by increasing the target temperature.The increase in the target temperature can improve the resolution and sensitivity of femtosecond LIBS.
基金supported by the National Natural Science Foundation of China(No.51603233)the Natural Science Foundation of Guangdong Province of China(Nos.2019A1515010550,2020A1515010439,2019A1515011389)the GDUPS(2019)the Opening Foundation of Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education(Sun Yat-sen University,No.PCFM-2019-05)。
文摘The development of organic materials with white-light emission and thermally activated delayed fluorescence(TADF)properties in the solid state remain a challenge.Herein,a series of white-light-emitting organic luminogens have been developed and are found to show aggregation-induced delayed fluorescence(AIDF)characteristics.The AIDF emitters present dual-emission consisted of prompt fluorescence and TADF in the crystalline state.Their white-light emissions can be easily tuned by altering the chemical structure and connecting position of the heterocyclic aromatic substituent.Under the stimuli of mechanical force and solvent vapor,the compounds exhibit remarkable and reversible mechanochromism,in which their emission colors are switchable between white and yellow.Upon grinding,they also display linearly tunable luminescence colors,as well as force-induced TADF enhancement,which may be associated with the more compact molecular packing and the restriction of intramolecular motions.The results from time-resolved emission scanning and theoretical calculation suggest that the dual-emission of the AIDF luminogens likely results from the twisted intramolecular charge transfer transitions of the molecules,and the reversible mechanochromism properties probably stem from the interconversion of the quasi-axial and the quasi-equatorial conformations.
基金supported by National Natural Science Foundation of China(Nos.11274254,11364037,11064012)the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics(No.11261140328)the International Scientic and Technologic Cooperative Project of Gansu Province,China(No.1104WCGA186)
文摘Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to produce plasmas on aluminum-based alloy in single- and collinear double-pulse laser induced breakdown spectroscopy (LIBS). Time resolved technique was used for detecting emission sig- nal by spectrometer equipped with ICCD detector. The intensity calibration of spectral response was performed by using deuterium and tungsten halogen lamps. Time evolution of the plasma temperature and electron number density was investigated in single- and collinear double-pulse experiments. Based on the investigation of plasma parameters, the emission signal enhancement mechanism was discussed qualitatively.
基金National Key R&D Program of China(2013CBA01703,2017YFA0303700)National Natural Science Foundation of China(NSFC)(11734011,61235009)
文摘Stimulated emission can be controlled by a material molecular energy band and the intensity of a pump laser, which can provide some population inversion and promote ground electron transition, respectively. We use a metallic optofluidic resonator to enhance stimulated emission intensity. The quality factor Q and the spontaneous emission coupling factor β of the metallic optofluidic resonator are discussed in detail to explain the enhancement mechanism. Experimental data demonstrate that the operated emission from rhodamin 6G solution can be observed due to the enhancement of stimulated emission from the optofluidic resonator.
基金This work was supported by the National Natural Science Foundation of China (No.39870212)
文摘Otoacoustic emissions (OAEs) has been considered as an excellent objective tool in clinics for diagnosing hearing loss. The signal-to-noise ratio (SNR) and correlation coefficient of OAEs are very important for the purpose of diagnosis. An adaptive signal enhancer (ASE) based on the Least Mean Square (LMS) algorithm is presented to detect transient evoked OAEs (TEOAEs). The TEOAEs detection results from 106 ears show that ASE reaches better estimation of TEOAEs than a conventional ensemble averaging (EA) technique. With the ASE, the improvement of SNR was increased faster than that with the EA and the number of sweeps required can be markedly reduced. The detection time with ASE could be shortened by about 50% in comparison with that of EA.
文摘We studied experimentally the effect of microwaves (MWs) on the enhancement of plasma emission achieved by laser-induced breakdown spectroscopy (LIBS). A laser plasma was generated on a calcium oxide pellet by a Nd:YAG laser (5 m J, 532 nm, 8 ns) in reduced-pressure argon surrounding gas. A MW radiation (400 W) was injected into the laser plasma via a loop antenna placed immediately above the laser plasma to enhance the plasma emission. The results confirmed that when tile electromagnetic field was introduced into the laser plasma region by the MWs, the lifetime of the plasma was extended from 50 to 500 μs, similar to the MW duration. Furthermore, the plasma temperature and electron density increased to approximately 10900 K and 1.5×10^18 cm^-3, respectively and the size of the plasma emission was extended to 15 mm in diameter. As a result, the emission intensity of Ca lines obtained using LIBS with MWs was enhanced by approximately 200 times compared to the case of LIBS without MWs.