Rosmarinic acid(RA)is promising as a natural and nontoxic food additive.However,many analysis methods for RA generally depend on large instruments and single signals for quantitative detection.A new upconversion fluor...Rosmarinic acid(RA)is promising as a natural and nontoxic food additive.However,many analysis methods for RA generally depend on large instruments and single signals for quantitative detection.A new upconversion fluorescence,colorimetric and photothermal multi-modal sensing strategy is developed for the quantification of RA.β-cyclodextrin(CD)modified citric acid(Cit)wrapped NaYF_(4):Yb/Er-Cit-CD(Y:Yb/Er-Cit-CD)up-conversion nanocomposite has been synthesized,which emits green fluorescence at 550nm under 980nm near-infrared(NIR)excitation.In the presence of oxidized 3,3',5,5'-tetramethylbenzidine(oxTMB),the green fluorescence is significantly quenched attributed to the fluorescence inner filter effect(IFE)between oxTMB and Y:Yb/Er-Cit-CD.When RA is intervened,blue oxTMB is reduced to colorless 3,3',5,5'-tetramethylbenzidine(TMB)inducing the recovery of up-conversion fluorescence.At the same time,colorimetric and photothermal signals readout can be easily achieved thanks to the color indication and photothermal effect of the oxTMB.The constructed Y:Yb/Er-Cit-CD/oxTMB sensor displays high sensitivity,visibility and simplicity for RA,and the limits of detection(LOD)for fluorescence,colorimetric and photothermal were 0.004μmol/L,0.036μmol/L and 0.043μmol/L,respectively.This sensing system is successfully performed for the detection of RA in food samples.展开更多
yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 30...yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated. The results show that the sensitivity of this sample reaches its maximum value, about 0.0047 K^-1, when the temperature is 383 K, indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.展开更多
The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time ...The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.展开更多
The linker defect engineering for MOFs is a viable strategy that usually can effectively augment conductivity to further promote charge carrier separation,which is the most excellent conductivity of preserved metal cl...The linker defect engineering for MOFs is a viable strategy that usually can effectively augment conductivity to further promote charge carrier separation,which is the most excellent conductivity of preserved metal clusters.However,the partially missing photosensitive linker often leads to the diminished light utilization efficiency.As we know,in the linker defect engineering,addressing the lack of photosensitivity while maintaining outstanding conductivity is still in its infancy.In this essay,the linkerdefective NH_(2)-MIL-125 was obtained by adding the glacial acetic acid regulator,subsequently,the excellent light-responsive Pt/CQDs with up-conversion effect was in-situ encapsulated into the enlarged pore space of linker-defective NH_(2)-MIL-125.It is excited that the fabricated dual-functional composite ideally integrates photosensitivity and conductivity for photocatalytic hydrogen evolution and NO elimination.The optimal Pt/CQDs@NM-125-4 exhibited very superior photocatalytic hydrogen evolution(28.75mmol/g),it was 11.63 times as that of the initial NH_(2)-MIL-125(2.47 mmol/g)and 1.4 times as that of the defective NM-125-4(20.46 mmol/g).In addition,the excellent photocatalytic NO removal efficiency was 52.12%for Pt/CQDs@NM-125-4,whereas the original NH_(2)-MIL-125 only reached 30%and the defective NM-125-4 achieved 44.96%.The corresponding optical and electrical characterization based on UV-vis,up-conversion photoluminescence(UCPL),and electrochemical impedance spectroscopy(EIS)etc.demonstrated the defect engineering accelerates the charge carriers transfer via enhancing conductivity,and the in-situ confined up-conversion Pt/CQDs promote the visible light response.Our work presents a feasible avenue to integrate photosensitivity and conductivity via in-situ fabricating excellent lightresponsive Pt/CQDs within linker-defective NH_(2)-MIL-125 for further significantly boosting photocatalytic performance.展开更多
To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through...To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through solid reaction process.The crystal structure,up-conversion luminescence,energy transfer,thermal stability and optical temperature sensing performances were studied in detail.Under 980 nm laser excitation,the KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor exhibits distinctive emission bands of Ho^(3+)at545,660,and 755 nm,and excellent illuminant performance.Based on the thermally coupled levels(TCLs)of Ho^(3+),both the relative sensitivity(S_(r))and absolute sensitivity(S_(a))display similar change trends,with the highest values of 6.73%/K(@298 K)and 5.69%/K(@298 K),respectively.Furthermore,the highest Saof 13.90%/K(@623 K)and the ultimate Srof 0.62%/K(@298 K)are achieved based on non-TCLs of Ho^(3+).Therefore,KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor is a promising candidate for self-referenced optical thermometry.展开更多
For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driv...For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driven by NIR light,NYFYT produces up-conversion emission at 348,364,453 and 478 nm,effectively stimulating the photocatalytic degradation performance of AP and AP/PtNPs,Under xenon lamp irradiation,the apparent rate constants(k)for Ag_(3)PO_(4)/Pt nanoparticles-NaYF4:Yb,Tm(AP/PtNPs-NYFYT)in photocatalytic degradation of rhodamine B(Rh B)and phenol are 5.51 and 12.82 times higher than those of AP and 1.90 and 2.37 times higher than those of AP-NYFYT-50 wt%,respectively.In addition,under 980nm laser irradiation,rate constants are 3.26 and 4.16 times higher than those of AP-NYFYT-50 wt%,respectively.These results indicate that the combination of NYFYT and AP expands the absorption range of the composite photocatalyst and facilitates the NIR-driven photocatalytic process.The introduction of PtNPs effectively prevents the electron-hole recombination and the reduction of Ag+,accelerating the redox reaction and promoting the photocatalytic activity and stability of AP.展开更多
A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used ...A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.展开更多
Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was deve...Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was developed. When the oxyfluoride glasses were heat-treated at the first crystallization temperature, the glasses gave transparent glass-ceramics in which rare earth containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Compared with the glasses before heat treatment, the glass-ceramics exhibited very strong blue up-conversion luminescence under 800 nm light excitation. Rare earth containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass, the size of precipitated nanocrystals could be controlled by laser power and scan speed. The intensity of the blue up-conversion luminescence was strongly dependent on the precipitation of β-PbF2 nanocrystal and the YbF3 concentration. The reasons for the highly efficient Tm^3＋ up-conversion luminescence after laser irradiation were discussed.展开更多
The possibility of ttming between red, green and broadband white color of up-conversion was demonstrated in thermally 450 ℃ treated Yb/Er co-doped nano NaYF4 phosphor. The color variability was studied by means of po...The possibility of ttming between red, green and broadband white color of up-conversion was demonstrated in thermally 450 ℃ treated Yb/Er co-doped nano NaYF4 phosphor. The color variability was studied by means of power dependence of luminescence, which exhibited unusual behavior. Large hysteresis, as well as discrepancy from a power law indicated the important role the increased heating played during the up-conversion in nano-sized materials.展开更多
Herein,we reported Er^3+/Yb^3+co-doped CaLaAl3O7 up-conversion phosphors synthesized via solid state reaction,which was further explored as a new optical thermometry.The luminescent properties of Er^3+or Er^3+/Yb^3+do...Herein,we reported Er^3+/Yb^3+co-doped CaLaAl3O7 up-conversion phosphors synthesized via solid state reaction,which was further explored as a new optical thermometry.The luminescent properties of Er^3+or Er^3+/Yb^3+doped CaLaAl3O7 phosphor was studied in detail.The two-photon process for the green emissions of Er^3+were confirmed by the power-dependent luminescence.The up-conversion optical temperature sensing performances of the Er^3+/Yb^3+-codoped CaLaAl3O7 phosphor were investigated based on the FIR technique.The maximum sensitivity of this phosphor can reach about 0.00345 K-1 at 453 K,which reveals this phosphor can be a promising candidate for optical thermometry devices.展开更多
A novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie...A novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie acid （OA） and 1-0ctadeeene （ODE） with Y2（COa）3＇xH20, Er2（COa）3xH20, Na2CO3 and NH4F as precursors. This proposed method was simple and less toxic compared with generally used method so far. The XRD results showed that the molar ratio of OA/ODE and the temperature were key factors for phase control ofNaYF4：Er NCs. The UC emission spectra were obtained with the emission wavelength at about 980 nm （4111/2--4115/2）, 800 nm （41912--415/2）, 660 nm （4F912--4115/2） and 540 nm （453/2----4115/2） from Er3＋ ions, by excitation wavelength of 1550 nm. The slope values, n, in the pump-power dependence, showed that the emission at 980 and 800 um were generated by 2-step UC and at 660 nm and 540 um were 3-step UC. The optical process for the UC excitation was discussed.展开更多
Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light c...Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.展开更多
A high-sensitive terahertz detector operating at room temperature was demonstrated based on parametric upconversion.A nanosecond 1064-nm Nd:YAG laser was used to pump the parametric up-conversion detector and the upco...A high-sensitive terahertz detector operating at room temperature was demonstrated based on parametric upconversion.A nanosecond 1064-nm Nd:YAG laser was used to pump the parametric up-conversion detector and the upconversion from terahertz wave to NIR laser was realized in a lithium niobate crystal.The minimum detectable terahertz energy of 9 p J was realized with the detection dynamic range of 54 d B,which was three orders of magnitude higher than that of commercial Golay cell.The detectable terahertz frequency range of the detection system was 0.90 Thz–1.83 THz.Besides,the effects of pump energy and effective gain length on the detection sensitivity were studied in experiment.The results showed that higher pump energy and longer effective gain length are helpful for improving the detection sensitivity of parametric up-conversion detector.展开更多
The up-conversion of Er3＋/yb3＋ co-doped transparent glass-ceramics 50SiO2-10A1F3-5TiO2-30BaF2-4LaF3-0.5ErF3-0.5YbF3 containing Ba2LaF7 nanocrystals under the changing of heat treatment temperature and time were inve...The up-conversion of Er3＋/yb3＋ co-doped transparent glass-ceramics 50SiO2-10A1F3-5TiO2-30BaF2-4LaF3-0.5ErF3-0.5YbF3 containing Ba2LaF7 nanocrystals under the changing of heat treatment temperature and time were investigated. The Ba2LaF7 nanocrystals precipitated from the glass matrix was confirmed by X-ray diffraction （XRD）. The structural investigation carried out by XRD and trans- mission electron microscopy （TEM） evidenced the formation of cubic Ba2LaF7 nanocrystals with crystal size of about 14 nm. Comparing with the samples before heat treatment, the high efficiency up-conversion emission of Er3＋/Yb3＋ co-doped samples was observed in the glass-ceramics under 980 nm laser diode excitation. The increase in red emission intensity bands was stronger than the green bands when the crystal size increased. The mechanism for the up-conversion process in the glass-ceramics and the reasons for the increase of Er3＋/yb3＋ co-doped up-conversion intensity after heat treatment were discussed.展开更多
The surface of an up-conversion luminescence material was modified by overcoating with SiOa, which was synthesized from a hydrolysis progress of telraethoxysilane （TEOS） in alkalescent condition. By analyzing the hy...The surface of an up-conversion luminescence material was modified by overcoating with SiOa, which was synthesized from a hydrolysis progress of telraethoxysilane （TEOS） in alkalescent condition. By analyzing the hydrolyzed mechanism of TEOS, it was found that there was not only physical adsorption but also chemical bonding between the up-conversion material and SiO2. At the same time, some adsorption bands at 1100, 475, 950, and 3500 cm^-1 were found by FI-IR, which were the characteristic bands of Si-OH and Si-O-Si. By analyzing the surface elements of the coated material by XPS, it was found that its surface only included Si, O, and C elements, and not F and Y. In the picture of XRD, there was no additional peak after surface modification, suggesting that the silica shell was amorphous. The small peak at 20 = 23° in the X-ray diffraction pattern of the coated material was caused by the amorphous SiO2 shell, and the TEM image also proved that the surface of the material was successfully modified by overcoating with SiO2. The amount of hydroxyls was then increased on the surface of the material, which made it easy to connect with other active groups.展开更多
In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation method.The crystal structure s and optical prope rties were investigated in detail.The...In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation method.The crystal structure s and optical prope rties were investigated in detail.The intensity of the emission of GdOF:Yb^(3+),Ho^(3+) phosphors is enhanced by the effective energy transfer from Yb^(3+) to Ho^(3+),and the optimal luminescence is achieved with the Ho^(3+)doping amount of 0.1 mol%as well as Yb^(3+) doping amount of 5 mol%.Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho^(3+) or Yb^(3+).The purity of the green UC emission is further improved by enhancing the excitation pumping power.In addition,logarithmic functions of green,red and nearinfrared radiation intensities were calculated versus logarithmic function of pump power for further study.A possible UC luminescence mechanism between Yb^(3+) and Ho^(3+) is discussed based on powerdependent UC luminescence spectrum and decay lifetimes.These results suggest that GdOF:Yb^(3+),Ho^(3+)phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging,display and illumination.展开更多
Rare earth luminescence has attracted widespread attention for several decades, among which nearinfrared(NIR) light-related up-conversion luminescence and NIR-Ⅱ luminescence are widely used in the biomedical field. T...Rare earth luminescence has attracted widespread attention for several decades, among which nearinfrared(NIR) light-related up-conversion luminescence and NIR-Ⅱ luminescence are widely used in the biomedical field. The NIR-related luminescence is widely studied due to the excellent performance, such as good biocompatibility, deep tissue penetration depth, low self-fluorescence and minimal light damage to organisms. In this review, we mainly introduce the mechanism for rare earth up-conversion luminescence, NIR-Ⅱ luminescence and conclude their advantages compared with traditional luminescence.These excellent priorities provide the basis for NIR-related luminescence bioimaging in vivo. Additionally,we hilglight the scheme for the sensitive detection of substances in organisms and various methods for biological therapy. In spite of the existing research, it is outlined that NIR-related luminescence has great potential to be applied in different aspects, expanding perspectives and future challenges of research in related fields. Based on the current scientific achievements, this review can provide reference for research in the areas mentioned above, expand the research direction and arouse a broad interest in different disciplines to pay attention to rare earth luminescence.展开更多
Up-conversion charging(UCC)is a promising approach for charging storage phosphors using low-energy excitation light sources.For further understanding the UCC,research on the competition between trapping and detrapping...Up-conversion charging(UCC)is a promising approach for charging storage phosphors using low-energy excitation light sources.For further understanding the UCC,research on the competition between trapping and detrapping during illumination is essentially required.Here we demonstrate the effect of detrapping on UCC dynamics by a rate equation approach.Accordingly,taking LaMgGa_(11)O_(19):Pr^(^(3+))phosphor as an example,we experimentally verified the dependence of illumination dose and duration on the thermoluminescence intensities using 450 nm laser excitation.The present model and experimental approach appear to be transferable to other phosphors,Thus,many existing persistent phosphors can now be revisited,paving the way toward advancing the understanding of UCC.展开更多
The oxy-fluorosilicate glasses co-doped with Yb3+/Tm3+ were prepared.The absorption spectra were recorded.The Tm3+ ion showed two absorption bands,with one at 774 nm due to 1G4→3H6 transition and the other at 667 nm ...The oxy-fluorosilicate glasses co-doped with Yb3+/Tm3+ were prepared.The absorption spectra were recorded.The Tm3+ ion showed two absorption bands,with one at 774 nm due to 1G4→3H6 transition and the other at 667 nm due to 1G4→3F4 transition.The energy transfer between Tm3+ ion and Yb3+ ion and the up-conversion fluorescence of Tm3+ ion were investigated using 980 nm LD excitation.The results showed that the blue and red emissions were three-photon absorption processes corresponding with 1G4→3H6 and 1G4→3F4...展开更多
Er3＋/Yb3＋ co-doped Li3Ba2Gd3（MoO4）8 phosphors were synthesized by conven- tional solid state reaction method, and their structure and spectral properties were investigated. The diffuse reflectance spectra showed t...Er3＋/Yb3＋ co-doped Li3Ba2Gd3（MoO4）8 phosphors were synthesized by conven- tional solid state reaction method, and their structure and spectral properties were investigated. The diffuse reflectance spectra showed that the 4I15/2→4I11/2 transition of Er3＋ and the 2F7/2→2F5/2 transition of Yb3＋ ions were highly overlapped. Under the excitation of 980 nm, three up-conver- sion （UC） luminescence bands around 530, 555 and 660 nm were observed, corresponding to the 2H11/2→ 4I15/2, 4S3/2 → 4I15/2 and 4F9/2-→4I15/2 transitions of Er3＋ ions, respectively. The effects of the concentration and pumping power on the UC intensities of Li3Ba2Gd3（MoO4）8：Er3＋/yb3＋ phosphors were investigated, and the possible UC mechanism was proposed based on the results.展开更多
基金supported by the National Natural Science Foundation of China(No.21305097)General Project of Education Department in Sichuan(No.035Z2270)+1 种基金Sichuan Key Discipline Construction Project of Traditional Chinese Medicine(No.2021-16-4)Double-Support Plan of Disciplinary Construction in Sichuan Agricultural University-Innovation Team Projects(No.P202108).
文摘Rosmarinic acid(RA)is promising as a natural and nontoxic food additive.However,many analysis methods for RA generally depend on large instruments and single signals for quantitative detection.A new upconversion fluorescence,colorimetric and photothermal multi-modal sensing strategy is developed for the quantification of RA.β-cyclodextrin(CD)modified citric acid(Cit)wrapped NaYF_(4):Yb/Er-Cit-CD(Y:Yb/Er-Cit-CD)up-conversion nanocomposite has been synthesized,which emits green fluorescence at 550nm under 980nm near-infrared(NIR)excitation.In the presence of oxidized 3,3',5,5'-tetramethylbenzidine(oxTMB),the green fluorescence is significantly quenched attributed to the fluorescence inner filter effect(IFE)between oxTMB and Y:Yb/Er-Cit-CD.When RA is intervened,blue oxTMB is reduced to colorless 3,3',5,5'-tetramethylbenzidine(TMB)inducing the recovery of up-conversion fluorescence.At the same time,colorimetric and photothermal signals readout can be easily achieved thanks to the color indication and photothermal effect of the oxTMB.The constructed Y:Yb/Er-Cit-CD/oxTMB sensor displays high sensitivity,visibility and simplicity for RA,and the limits of detection(LOD)for fluorescence,colorimetric and photothermal were 0.004μmol/L,0.036μmol/L and 0.043μmol/L,respectively.This sensing system is successfully performed for the detection of RA in food samples.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10804015 )the Science Foundation of the Education Department of Liaoning Province of China (Grant No. 2009A417)
文摘yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated. The results show that the sensitivity of this sample reaches its maximum value, about 0.0047 K^-1, when the temperature is 383 K, indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11074003 and 20973001)the Key Program of Educational Commission of Anhui Province of China (Grant No. KJ2010A132)
文摘The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.
基金supported by the National Natural Science Foundation of China(Nos.22001026,22171233,22201193)Sichuan Science and Technology Program(No.2023NSFSC0109)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Hundred Talent Program of Sichuan University(No.YJ2021158)。
文摘The linker defect engineering for MOFs is a viable strategy that usually can effectively augment conductivity to further promote charge carrier separation,which is the most excellent conductivity of preserved metal clusters.However,the partially missing photosensitive linker often leads to the diminished light utilization efficiency.As we know,in the linker defect engineering,addressing the lack of photosensitivity while maintaining outstanding conductivity is still in its infancy.In this essay,the linkerdefective NH_(2)-MIL-125 was obtained by adding the glacial acetic acid regulator,subsequently,the excellent light-responsive Pt/CQDs with up-conversion effect was in-situ encapsulated into the enlarged pore space of linker-defective NH_(2)-MIL-125.It is excited that the fabricated dual-functional composite ideally integrates photosensitivity and conductivity for photocatalytic hydrogen evolution and NO elimination.The optimal Pt/CQDs@NM-125-4 exhibited very superior photocatalytic hydrogen evolution(28.75mmol/g),it was 11.63 times as that of the initial NH_(2)-MIL-125(2.47 mmol/g)and 1.4 times as that of the defective NM-125-4(20.46 mmol/g).In addition,the excellent photocatalytic NO removal efficiency was 52.12%for Pt/CQDs@NM-125-4,whereas the original NH_(2)-MIL-125 only reached 30%and the defective NM-125-4 achieved 44.96%.The corresponding optical and electrical characterization based on UV-vis,up-conversion photoluminescence(UCPL),and electrochemical impedance spectroscopy(EIS)etc.demonstrated the defect engineering accelerates the charge carriers transfer via enhancing conductivity,and the in-situ confined up-conversion Pt/CQDs promote the visible light response.Our work presents a feasible avenue to integrate photosensitivity and conductivity via in-situ fabricating excellent lightresponsive Pt/CQDs within linker-defective NH_(2)-MIL-125 for further significantly boosting photocatalytic performance.
基金supported by the National Natural Science Foundation of China(61865003)。
文摘To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through solid reaction process.The crystal structure,up-conversion luminescence,energy transfer,thermal stability and optical temperature sensing performances were studied in detail.Under 980 nm laser excitation,the KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor exhibits distinctive emission bands of Ho^(3+)at545,660,and 755 nm,and excellent illuminant performance.Based on the thermally coupled levels(TCLs)of Ho^(3+),both the relative sensitivity(S_(r))and absolute sensitivity(S_(a))display similar change trends,with the highest values of 6.73%/K(@298 K)and 5.69%/K(@298 K),respectively.Furthermore,the highest Saof 13.90%/K(@623 K)and the ultimate Srof 0.62%/K(@298 K)are achieved based on non-TCLs of Ho^(3+).Therefore,KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor is a promising candidate for self-referenced optical thermometry.
基金Project supported by Hebei Province High-level Talent(Postdoctor)Funding Project(B2022003025)。
文摘For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driven by NIR light,NYFYT produces up-conversion emission at 348,364,453 and 478 nm,effectively stimulating the photocatalytic degradation performance of AP and AP/PtNPs,Under xenon lamp irradiation,the apparent rate constants(k)for Ag_(3)PO_(4)/Pt nanoparticles-NaYF4:Yb,Tm(AP/PtNPs-NYFYT)in photocatalytic degradation of rhodamine B(Rh B)and phenol are 5.51 and 12.82 times higher than those of AP and 1.90 and 2.37 times higher than those of AP-NYFYT-50 wt%,respectively.In addition,under 980nm laser irradiation,rate constants are 3.26 and 4.16 times higher than those of AP-NYFYT-50 wt%,respectively.These results indicate that the combination of NYFYT and AP expands the absorption range of the composite photocatalyst and facilitates the NIR-driven photocatalytic process.The introduction of PtNPs effectively prevents the electron-hole recombination and the reduction of Ag+,accelerating the redox reaction and promoting the photocatalytic activity and stability of AP.
文摘A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.
基金supported by the National Natural Science Foundation of China (50572029) Natural Science Foundation Project of Yunnan Province (2007E036M)
文摘Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was developed. When the oxyfluoride glasses were heat-treated at the first crystallization temperature, the glasses gave transparent glass-ceramics in which rare earth containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Compared with the glasses before heat treatment, the glass-ceramics exhibited very strong blue up-conversion luminescence under 800 nm light excitation. Rare earth containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass, the size of precipitated nanocrystals could be controlled by laser power and scan speed. The intensity of the blue up-conversion luminescence was strongly dependent on the precipitation of β-PbF2 nanocrystal and the YbF3 concentration. The reasons for the highly efficient Tm^3＋ up-conversion luminescence after laser irradiation were discussed.
基金Project supported by Polish National Science Centre (N N507 584938,N N507599038)the Foundation for Polish Science
文摘The possibility of ttming between red, green and broadband white color of up-conversion was demonstrated in thermally 450 ℃ treated Yb/Er co-doped nano NaYF4 phosphor. The color variability was studied by means of power dependence of luminescence, which exhibited unusual behavior. Large hysteresis, as well as discrepancy from a power law indicated the important role the increased heating played during the up-conversion in nano-sized materials.
基金Project supported by National Natural Science Foundation of China(51802069,61205180)the First Batch of Young Talent Support Plan of Hebei ProvinceGraduate Student Innovation Project of Hebei University(hbu2018ss62)
文摘Herein,we reported Er^3+/Yb^3+co-doped CaLaAl3O7 up-conversion phosphors synthesized via solid state reaction,which was further explored as a new optical thermometry.The luminescent properties of Er^3+or Er^3+/Yb^3+doped CaLaAl3O7 phosphor was studied in detail.The two-photon process for the green emissions of Er^3+were confirmed by the power-dependent luminescence.The up-conversion optical temperature sensing performances of the Er^3+/Yb^3+-codoped CaLaAl3O7 phosphor were investigated based on the FIR technique.The maximum sensitivity of this phosphor can reach about 0.00345 K-1 at 453 K,which reveals this phosphor can be a promising candidate for optical thermometry devices.
文摘A novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie acid （OA） and 1-0ctadeeene （ODE） with Y2（COa）3＇xH20, Er2（COa）3xH20, Na2CO3 and NH4F as precursors. This proposed method was simple and less toxic compared with generally used method so far. The XRD results showed that the molar ratio of OA/ODE and the temperature were key factors for phase control ofNaYF4：Er NCs. The UC emission spectra were obtained with the emission wavelength at about 980 nm （4111/2--4115/2）, 800 nm （41912--415/2）, 660 nm （4F912--4115/2） and 540 nm （453/2----4115/2） from Er3＋ ions, by excitation wavelength of 1550 nm. The slope values, n, in the pump-power dependence, showed that the emission at 980 and 800 um were generated by 2-step UC and at 660 nm and 540 um were 3-step UC. The optical process for the UC excitation was discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92065101 and 11934013)Anhui Initiative In Quantum Information Technologies(Grant No.AHY020200)。
文摘Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1837202,61775160,61771332,62011540006,and 62175182)。
文摘A high-sensitive terahertz detector operating at room temperature was demonstrated based on parametric upconversion.A nanosecond 1064-nm Nd:YAG laser was used to pump the parametric up-conversion detector and the upconversion from terahertz wave to NIR laser was realized in a lithium niobate crystal.The minimum detectable terahertz energy of 9 p J was realized with the detection dynamic range of 54 d B,which was three orders of magnitude higher than that of commercial Golay cell.The detectable terahertz frequency range of the detection system was 0.90 Thz–1.83 THz.Besides,the effects of pump energy and effective gain length on the detection sensitivity were studied in experiment.The results showed that higher pump energy and longer effective gain length are helpful for improving the detection sensitivity of parametric up-conversion detector.
基金Project supported by National Natural Science Foundation of China(51272097,61265004,51002068)973 Program(2011CB211708)+4 种基金Society Development Foundation of Yunnan Province(2009CC009)Natural Science Foundation of Yunnan Province(2010ZC038)Postdoctoral Science Foundation of China(20110491759)Education Department Foundation of Yunnan Province(2011Y348)Foundation of Yunnan Province(2012FD009)
文摘The up-conversion of Er3＋/yb3＋ co-doped transparent glass-ceramics 50SiO2-10A1F3-5TiO2-30BaF2-4LaF3-0.5ErF3-0.5YbF3 containing Ba2LaF7 nanocrystals under the changing of heat treatment temperature and time were investigated. The Ba2LaF7 nanocrystals precipitated from the glass matrix was confirmed by X-ray diffraction （XRD）. The structural investigation carried out by XRD and trans- mission electron microscopy （TEM） evidenced the formation of cubic Ba2LaF7 nanocrystals with crystal size of about 14 nm. Comparing with the samples before heat treatment, the high efficiency up-conversion emission of Er3＋/Yb3＋ co-doped samples was observed in the glass-ceramics under 980 nm laser diode excitation. The increase in red emission intensity bands was stronger than the green bands when the crystal size increased. The mechanism for the up-conversion process in the glass-ceramics and the reasons for the increase of Er3＋/yb3＋ co-doped up-conversion intensity after heat treatment were discussed.
基金the National Natural Science Foundation of China (Nos. 50372006, 20273007, and 20407003).
文摘The surface of an up-conversion luminescence material was modified by overcoating with SiOa, which was synthesized from a hydrolysis progress of telraethoxysilane （TEOS） in alkalescent condition. By analyzing the hydrolyzed mechanism of TEOS, it was found that there was not only physical adsorption but also chemical bonding between the up-conversion material and SiO2. At the same time, some adsorption bands at 1100, 475, 950, and 3500 cm^-1 were found by FI-IR, which were the characteristic bands of Si-OH and Si-O-Si. By analyzing the surface elements of the coated material by XPS, it was found that its surface only included Si, O, and C elements, and not F and Y. In the picture of XRD, there was no additional peak after surface modification, suggesting that the silica shell was amorphous. The small peak at 20 = 23° in the X-ray diffraction pattern of the coated material was caused by the amorphous SiO2 shell, and the TEM image also proved that the surface of the material was successfully modified by overcoating with SiO2. The amount of hydroxyls was then increased on the surface of the material, which made it easy to connect with other active groups.
基金Project supported by the National Natural Science Foundation of China(51202111)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation method.The crystal structure s and optical prope rties were investigated in detail.The intensity of the emission of GdOF:Yb^(3+),Ho^(3+) phosphors is enhanced by the effective energy transfer from Yb^(3+) to Ho^(3+),and the optimal luminescence is achieved with the Ho^(3+)doping amount of 0.1 mol%as well as Yb^(3+) doping amount of 5 mol%.Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho^(3+) or Yb^(3+).The purity of the green UC emission is further improved by enhancing the excitation pumping power.In addition,logarithmic functions of green,red and nearinfrared radiation intensities were calculated versus logarithmic function of pump power for further study.A possible UC luminescence mechanism between Yb^(3+) and Ho^(3+) is discussed based on powerdependent UC luminescence spectrum and decay lifetimes.These results suggest that GdOF:Yb^(3+),Ho^(3+)phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging,display and illumination.
基金Financial support from the National Natural Science Foundation of China(NSFC,Nos.51972076,52272144,22205048)the Heilongjiang Provincial Natural Science Foundation of China(No.JQ2022E001)+3 种基金the Natural Science Foundation of Shandong Province(No.ZR2020ZD42)Project funded by China Postdoctoral Science Foundation(No.2022M710931)the Fundamental Research Funds for the Central Universitiesthe Special Scientific Research Starting Foundation for Young teachers of Zhengzhou University(No.32213226).
文摘Rare earth luminescence has attracted widespread attention for several decades, among which nearinfrared(NIR) light-related up-conversion luminescence and NIR-Ⅱ luminescence are widely used in the biomedical field. The NIR-related luminescence is widely studied due to the excellent performance, such as good biocompatibility, deep tissue penetration depth, low self-fluorescence and minimal light damage to organisms. In this review, we mainly introduce the mechanism for rare earth up-conversion luminescence, NIR-Ⅱ luminescence and conclude their advantages compared with traditional luminescence.These excellent priorities provide the basis for NIR-related luminescence bioimaging in vivo. Additionally,we hilglight the scheme for the sensitive detection of substances in organisms and various methods for biological therapy. In spite of the existing research, it is outlined that NIR-related luminescence has great potential to be applied in different aspects, expanding perspectives and future challenges of research in related fields. Based on the current scientific achievements, this review can provide reference for research in the areas mentioned above, expand the research direction and arouse a broad interest in different disciplines to pay attention to rare earth luminescence.
基金Project supported by the National Natural Science Foundation of China(11774046)the Department of Science and Technology of Jilin Province(20180414082 GH)。
文摘Up-conversion charging(UCC)is a promising approach for charging storage phosphors using low-energy excitation light sources.For further understanding the UCC,research on the competition between trapping and detrapping during illumination is essentially required.Here we demonstrate the effect of detrapping on UCC dynamics by a rate equation approach.Accordingly,taking LaMgGa_(11)O_(19):Pr^(^(3+))phosphor as an example,we experimentally verified the dependence of illumination dose and duration on the thermoluminescence intensities using 450 nm laser excitation.The present model and experimental approach appear to be transferable to other phosphors,Thus,many existing persistent phosphors can now be revisited,paving the way toward advancing the understanding of UCC.
文摘The oxy-fluorosilicate glasses co-doped with Yb3+/Tm3+ were prepared.The absorption spectra were recorded.The Tm3+ ion showed two absorption bands,with one at 774 nm due to 1G4→3H6 transition and the other at 667 nm due to 1G4→3F4 transition.The energy transfer between Tm3+ ion and Yb3+ ion and the up-conversion fluorescence of Tm3+ ion were investigated using 980 nm LD excitation.The results showed that the blue and red emissions were three-photon absorption processes corresponding with 1G4→3H6 and 1G4→3F4...
基金supported by the Natural Science Foundation of Shandong Province(ZR2014JL029,BS2015CL012,ZR2015BM005)
文摘Er3＋/Yb3＋ co-doped Li3Ba2Gd3（MoO4）8 phosphors were synthesized by conven- tional solid state reaction method, and their structure and spectral properties were investigated. The diffuse reflectance spectra showed that the 4I15/2→4I11/2 transition of Er3＋ and the 2F7/2→2F5/2 transition of Yb3＋ ions were highly overlapped. Under the excitation of 980 nm, three up-conver- sion （UC） luminescence bands around 530, 555 and 660 nm were observed, corresponding to the 2H11/2→ 4I15/2, 4S3/2 → 4I15/2 and 4F9/2-→4I15/2 transitions of Er3＋ ions, respectively. The effects of the concentration and pumping power on the UC intensities of Li3Ba2Gd3（MoO4）8：Er3＋/yb3＋ phosphors were investigated, and the possible UC mechanism was proposed based on the results.
