As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accu...As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accurately.In comparison to conventional fluorescent materials such as organic dyes,quantum dot(QD)labels,and carbon quantum dots(CD),fluorescence detection technology utilizing lanthanide(Ln)ion-doped upconversion nanoparticles(UCNPs)stands out due to its distinctive attributes.These include a notably reduced autofluorescence background,enhanced tissue penetration capabilities,biocompatibility with cellular tissues,and minimal photodamage inflicted on biological samples.The utilization of this technology has garnered considerable attention across multiple fields.In the domain of heavy metal detection,traditional laboratory methods necessitate costly instrumentation and a fully equipped laboratory,involving intricate sample processing procedures and protracted detection periods,as well as a demand for skilled personnel.In contrast,the implementation of this material offers rapid and cost-effective detection,significantly mitigating the technical barriers for operators.Consequently,this represents an exceptional avenue to curtail expenses and broaden the scope of detection within the analytical process.This paper reviews the research progress of UCNPs in the detection of heavy metal ions,encompassing a brief elucidation of the luminescence principle of upconversion nanomaterials and commonly used detection principles.Additionally,it provides a detailed overview of the research status of several common non-metal ions and essential heavy metals.Furthermore,it summarizes the current focal points in UCNP detection and discusses the challenges and prospects associated with it.展开更多
Quantum emitters are widely used in quantum networks,quantum information processing,and quantum sensing due to their excellent optical properties.Compared with Stokes excitation,quantum emitters under anti-Stokes exci...Quantum emitters are widely used in quantum networks,quantum information processing,and quantum sensing due to their excellent optical properties.Compared with Stokes excitation,quantum emitters under anti-Stokes excitation exhibit better performance.In addition to laser cooling and nanoscale thermometry,anti-Stokes excitation can improve the coherence of single-photon sources for advanced quantum technologies.In this review,we follow the recent advances in phononassisted upconversion photoluminescence of quantum emitters and discuss the upconversion mechanisms,applications,and prospects for quantum emitters with anti-Stokes excitation.展开更多
A new upconversion luminescence agent, 40CdF2·60BaF2·0.8ErO3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks sh...A new upconversion luminescence agent, 40CdF2·60BaF2·0.8ErO3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.展开更多
Nanocrystal of upconversion (UC) phosphor Ho^3+, Tm^3+ , and Yb^3+ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the imp...Nanocrystal of upconversion (UC) phosphor Ho^3+, Tm^3+ , and Yb^3+ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3+ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The result shows that Ho^3+ ,Tm^3+ , and Yb^3+ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.展开更多
Y2O3: Er^3+, Yb^3+ nanoparticles were synthesized by a homogeneous precipitation method without and with different concentrations of EDTA 2Na. Upconversion luminescence spectra of the samples were studied under 980...Y2O3: Er^3+, Yb^3+ nanoparticles were synthesized by a homogeneous precipitation method without and with different concentrations of EDTA 2Na. Upconversion luminescence spectra of the samples were studied under 980 nm laser excitation. The results of XRD showed that the obtained Y2O3:Er^3+,Yb^3+ nanoparticles were of a cubic structure. The average crystallite sizes calculated were in the range of 28-40 nm. Green and red upconversion emission were observed, and attributed to ^2H11/2,^4S3/2→^4I15/2 and ^4F9/2→^4I15/2 transitions of the ion, respectively. The ratio of the intensity of green emission to that of red emission drastically changed with a change in the EDTA 2Na concentration. In the sample synthesized without EDTA, the relative intensity of the green emission was weaker than that of the red emission. The relative intensities of green emission increased with the increased amount of EDTA 2Na used. The possible upconversion luminescence mechanisms were discussed.展开更多
Y2O3:Er^3+ films were prepared by a simple sol-gel process. The structural properties of Y2O3:Er^3+ films were characterized with X-ray diffraction, Fourier transform infrared spectroscopy and field emission scann...Y2O3:Er^3+ films were prepared by a simple sol-gel process. The structural properties of Y2O3:Er^3+ films were characterized with X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The results indicated that the Y2O3:Er^3+ films might have high upconversion efficiency because of their low vibrational energy. Under 785 and 980 nm laser excitation, the samples showed green (^2H11/2→^4I15/2, ^4S3/2→^4I15/2) and red (^4F9/2→^4I15/2) upconversion emissions. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer process were discussed as possible upconversion mechanisms. The cross relaxation process in Er^3+ was also investigated.展开更多
Cubic NaYF4:Yb^3+(20%)/Er^3+(1%) microspheres were synthesized by EDTA-assisted hydrothermal method. Under 980 nm excitation, ultraviolet (^4G11/2→^4I15/2), violet (^2H9/2→^4I15/2), green (^4F7/2→^4I15/...Cubic NaYF4:Yb^3+(20%)/Er^3+(1%) microspheres were synthesized by EDTA-assisted hydrothermal method. Under 980 nm excitation, ultraviolet (^4G11/2→^4I15/2), violet (^2H9/2→^4I15/2), green (^4F7/2→^4I15/2, 2H11/2→^4I15/2, and ^4S3/2→^4I15/2), and red (^4F9/2→^4I15/2) upconversion fluorescence were observed. The number of laser photons absorbed in one upconversion excitation process, n, was determined to be 3.89, 1.61, 2.55, and 1.09 for the ultraviolet, violet, green, and red emissions, respectively. Obviously, n=3.89 indicated that a four-photon process was involved in populating the ^4G11/2 state, and n=2.55 indicated that a three-photon process was involved in populating the ^4F7/2/^2H11/2/^4S3/2 levels. For the violet and red emissions, the population of the states ^2H9/2 and ^4F9/2 separately came from three-photon and two-photon processes. The decrease of n was well explained by the mechanism of competition between linear decay and upconversion processes for the depletion of the intermediate excited states.展开更多
Y2O3:Er^3+ ultrafine phosphors with a varying Yb^3+ ion concentration were prepared by a urea homogeneous precipitation method. The results of XRD show that all the samples are of a pure cubic structure and the ave...Y2O3:Er^3+ ultrafine phosphors with a varying Yb^3+ ion concentration were prepared by a urea homogeneous precipitation method. The results of XRD show that all the samples are of a pure cubic structure and the average crystallite sizes can be calculated as 45, 34, and 28 nm for Y2O3:Er^3+ ultrafine phosphors with Yb^3+ ion concentrations of 0, 10%, and 20%, respectively. The lattice constant and cell volume of the ultrafine phosphors decrease with enhancing Yb^3+ ion concentration. The upconversion luminescence spectra of all the samples were studied under 980 nm laser excitation. The strong green and red upconversion emission were observed, and attributed to the ^2H11/2→^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 →^4I15/2 transitions of Er^3+, respectively. The intensity of red emission increases with increasing Yb^3+ ion concentration. The effect of Yb^3+ ion concentration on the structures and upconversion luminescence mechanism were discussed.展开更多
Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate (BK7) glass containing Ce^3 + ions under focused infrared femtosecond laser irradiation. The emission spectra show that t...Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate (BK7) glass containing Ce^3 + ions under focused infrared femtosecond laser irradiation. The emission spectra show that the upconversion luminescence comes from the 4f-5d transition of the Ce^3 + ions. The relationship between the intensity of the Ce^3 + emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.展开更多
Fluorescently encoded microbeads are in demand for multiplexed applications in different fields.Compared to organic dye-based commercially available Luminex's x MAP technology, upconversion nanoparticles(UCNPs) ar...Fluorescently encoded microbeads are in demand for multiplexed applications in different fields.Compared to organic dye-based commercially available Luminex's x MAP technology, upconversion nanoparticles(UCNPs) are better alternatives due to their large antiStokes shift, photostability, nil background, and single wavelength excitation. Here, we developed a new multiplexed detection system using UCNPs for encoding poly(ethylene glycol) diacrylate(PEGDA) microbeads as well as for labeling reporter antibody. However, to prepare UCNPs-encoded microbeads, currently used swellingbased encapsulation leads to non-uniformity, which is undesirable for fluorescence-based multiplexing. Hence,we utilized droplet microfluidics to obtain encoded microbeads of uniform size, shape, and UCNPs distribution inside. Additionally, PEGDA microbeads lack functionality for probe antibodies conjugation on their surface.Methods to functionalize the surface of PEGDA microbeads(acrylic acid incorporation, polydopamine coating)reported thus far quench the fluorescence of UCNPs. Here,PEGDA microbeads surface was coated with silica followed by carboxyl modification without compromising the fluorescence intensity of UCNPs. In this study, droplet microfluidics-assisted UCNPs-encoded microbeads of uniform shape, size, and fluorescence were prepared.Multiple color codes were generated by mixing UCNPs emitting red and green colors at different ratios prior to encapsulation. UCNPs emitting blue color were used to label the reporter antibody. Probe antibodies were covalently immobilized on red UCNPs-encoded microbeads for specific capture of human serum albumin(HSA) as a model protein. The system was also demonstrated for multiplexed detection of both human C-reactive protein(hCRP) and HSA protein by immobilizing anti-h CRP antibodies on green UCNPs.展开更多
The upconversion emission spectra of Er^3+ doped oxyfluoride tellurite glasses excited by 808 nm laser diode (LD) were measured. The dependence of 550 nm upconversion emission on the excitation intensity was analyz...The upconversion emission spectra of Er^3+ doped oxyfluoride tellurite glasses excited by 808 nm laser diode (LD) were measured. The dependence of 550 nm upconversion emission on the excitation intensity was analyzed. Quadratic intensity dependence was only observed at weak excitation intensity. With increasing the excitation intensity, saturation was turned out. The experimental results were fitted to a model based on the rate equations.展开更多
Cubic YAG:Yb3+, Ho3+ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials.After calcining the precipitates at 800 °C, the resultant YAG:Yb3...Cubic YAG:Yb3+, Ho3+ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials.After calcining the precipitates at 800 °C, the resultant YAG:Yb3+, Ho3+ nanocrystals were nearly spheric and the particle size was about 40 nm.Intense upconversion spectra were observed on the powder compact pumped by a 980 nm continuous wave diode laser, and green emission centered at 549 nm, red emission centered at 667 nm, and NIR centered at 760 nm were all due to two photons process, which originated from 5S2(5F4)→5I8, 5F5→5I8, and 5S2(5F4)→5I7 transitions, respectively.展开更多
Nd^3+ doped transparent oxyfiuoride glass ceramic containing β-YF3 nanocrystals was prepared and the upconversion luminescence behaviors of Nd^3+ in the precursor glass and glass ceramic were investigated. Under 79...Nd^3+ doped transparent oxyfiuoride glass ceramic containing β-YF3 nanocrystals was prepared and the upconversion luminescence behaviors of Nd^3+ in the precursor glass and glass ceramic were investigated. Under 796 nm laser excitation, ultraviolet upconversion emissions of Nd^3+ ions at 354 nm (^4D3/2→^4I11/2) and 382 nm (^4D3/2→^4I11/2) were observed at room temperature. Power dependence analysis demonstrated that three-photon upconversion processes populated the ^4D3/2 excited state. In comparison with those of the precursor glass, the ultraviolet emissions were enhanced by a factor of 500 in the glass ceramic, which was attributed to the change in the ligand field of Nd^3+ ions and the decrease in phonon energy because of the partition of Nd^3+ ions into the β-YF3 nanocrystals after crystallization.展开更多
The red, green, and blue upconversion properties of Er^3+/Tm^3+/Yb^3+-codoped oxyhalide tellurite glasses were studied under 980 nm LD excitation. The intense red (657 nm), green (530 and 545 nm), and blue (47...The red, green, and blue upconversion properties of Er^3+/Tm^3+/Yb^3+-codoped oxyhalide tellurite glasses were studied under 980 nm LD excitation. The intense red (657 nm), green (530 and 545 nm), and blue (476 nm) emissions were simultaneously observed at room temperature. The results showed that the mixed halide modified tellurite glass (TZFCB) had strong upconversion emissions. The effect of halide on upconversion intensity was observed and discussed, and possible upconversion mechanisms were evaluated. The intense red, green, and blue upconversion luminescence of Er^3+/Tm^3+/Yb^3+-codoped oxyhalide tellurite glasses might be a potentially useful material for developing three-dimensional displays applications.展开更多
LaF3:Yb^3+ , Er^+ microcrystals were synthesized by a hydrothermal method, and then, the LaF3: Yb^3+ , Er^+ microcrystals were coated with silica. Phase identification of LaF3: Yb^3+ , Er^+ and LaF3: Yb^3+ ...LaF3:Yb^3+ , Er^+ microcrystals were synthesized by a hydrothermal method, and then, the LaF3: Yb^3+ , Er^+ microcrystals were coated with silica. Phase identification of LaF3: Yb^3+ , Er^+ and LaF3: Yb^3+ , Er^+/SiO2 was performed via XRD. The TEM image showed that the size of LaF3: Yb^3+ , Er^+ was 150 nm and LaF3: Yb^3+ , Er^+/SiO2 presented clearly a core/shell structure with 20 nm shell thickness. The upconversion spectra of LaF3: Yb^3+ , Er^+ and LaF3: Yb^3+ , Er^+/SiO2 in solid state and in ethanol were studied with a 980 nm diode laser as the excitation source. The upconversion spectra showed that the silica shell had little effect on the properties of fluorescence of the LaF3:Yb^3+ , Er^+ microcrystals. At the same time, the green luminescence photo of LaF3: Yb3+, Er3+/SiO2 in the PBS buffer was obtained, which indicated that the LaF3: Yb^3+ , Er^+/SiO2 could be used in biological applications.展开更多
This paper reports that the ultraviolet and visible upconversion luminescence from the ^4S3/2, ^2G9/2 and ^2P3/2 levels have been observed in Er^3+:YAG following 647.2 nm excitation of the ^4F9/2 multiple. Upconvers...This paper reports that the ultraviolet and visible upconversion luminescence from the ^4S3/2, ^2G9/2 and ^2P3/2 levels have been observed in Er^3+:YAG following 647.2 nm excitation of the ^4F9/2 multiple. Upconversion luminescence intensity dependence on pump power was recorded. The measured decay profiles were theoretically fitted by kinetics theory and the basically good agreements were achieved. The results indicate that some energy transfer processes proposed to explain the observed upconversion phenomena are reasonable.展开更多
Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - (4.9 - x) AlF3(x=0, 0.5, 1.0, 1.5, 2.0) in tool fraction, Furthermore, the upconversion luminescence c...Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - (4.9 - x) AlF3(x=0, 0.5, 1.0, 1.5, 2.0) in tool fraction, Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm^3+: ^1D2 →^3F4, ^1G4 →^3H6, ^1G4 →^3F4, and ^3H4 →^3H6, respectively, are observed. Due to the sensitization of Yb^3+ ions, all the upconversion luminescence intensities are enhanced considerably with Yb^3+ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.展开更多
Erbium, Ytterbium-codoped ZrO 2 nanoparticles(ZrO 2∶Er 3+ ,Yb 3+ ) were prepared by the sol-emulsion-gel technique. The purpose of the present study is the application of upconversion phosphor in the biolog...Erbium, Ytterbium-codoped ZrO 2 nanoparticles(ZrO 2∶Er 3+ ,Yb 3+ ) were prepared by the sol-emulsion-gel technique. The purpose of the present study is the application of upconversion phosphor in the biological label. In order to make out the mechanism of upconversion under 980 nm excitation the 488 nm pump was used. The influence of temperature on the crystallite phase was studied. The results confirm the upconverted mechanism in ZrO 2∶Er 3+ ,Yb 3+ nanocrystals is due to an energy transfer upconversion(ETU).展开更多
The upconversion luminescence and dynamics in Er^3+ /Yb^3+ codoped nanocrystalline yttria (7-65 nm) are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the gre...The upconversion luminescence and dynamics in Er^3+ /Yb^3+ codoped nanocrystalline yttria (7-65 nm) are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the green emission of ^2H11/2/^4S3/2 in nanoparticles with lower concentration of Yb^3+ result from a two-photon excitation, In nanocrystals with higher Yb^3+ concentration, the red emissions from a two-photon excitation, while the green emissions from a three-photon excitation, The luminescence dynamics indicates that as the particle size decreases, both the rise and the decay time constants become shorter, As the size decreases to several nanometres, the rise process nearly disappears, suggesting that the upconversion luminescence originates mainly from self-excitation of Er^3+, instead of the energy transfer of Yb^3+→ Er^3+.展开更多
Intense upconversion emissions of YLiF 4∶Er 3+ synthesized by hydrothermal method were obtained. The upconversion intensity decreases with the increase of environment temperature. In different temperature, the ...Intense upconversion emissions of YLiF 4∶Er 3+ synthesized by hydrothermal method were obtained. The upconversion intensity decreases with the increase of environment temperature. In different temperature, the upconversion mechanism is different. At room temperature, the green upconversion mechanism is the combination of two photon process and three photon process, and the red upconversion mechanism is two photon process.展开更多
基金supported by the Science and Technology Development Fund,Macao SAR(Grant 0065/2023/ITP2).
文摘As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accurately.In comparison to conventional fluorescent materials such as organic dyes,quantum dot(QD)labels,and carbon quantum dots(CD),fluorescence detection technology utilizing lanthanide(Ln)ion-doped upconversion nanoparticles(UCNPs)stands out due to its distinctive attributes.These include a notably reduced autofluorescence background,enhanced tissue penetration capabilities,biocompatibility with cellular tissues,and minimal photodamage inflicted on biological samples.The utilization of this technology has garnered considerable attention across multiple fields.In the domain of heavy metal detection,traditional laboratory methods necessitate costly instrumentation and a fully equipped laboratory,involving intricate sample processing procedures and protracted detection periods,as well as a demand for skilled personnel.In contrast,the implementation of this material offers rapid and cost-effective detection,significantly mitigating the technical barriers for operators.Consequently,this represents an exceptional avenue to curtail expenses and broaden the scope of detection within the analytical process.This paper reviews the research progress of UCNPs in the detection of heavy metal ions,encompassing a brief elucidation of the luminescence principle of upconversion nanomaterials and commonly used detection principles.Additionally,it provides a detailed overview of the research status of several common non-metal ions and essential heavy metals.Furthermore,it summarizes the current focal points in UCNP detection and discusses the challenges and prospects associated with it.
基金the National Key Research and Development Program of China(2017YFA0303401)the CAS Interdisciplinary Innovation Team,the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDB28000000)the NSFC(12074371,U21A2070,and 62027816)。
文摘Quantum emitters are widely used in quantum networks,quantum information processing,and quantum sensing due to their excellent optical properties.Compared with Stokes excitation,quantum emitters under anti-Stokes excitation exhibit better performance.In addition to laser cooling and nanoscale thermometry,anti-Stokes excitation can improve the coherence of single-photon sources for advanced quantum technologies.In this review,we follow the recent advances in phononassisted upconversion photoluminescence of quantum emitters and discuss the upconversion mechanisms,applications,and prospects for quantum emitters with anti-Stokes excitation.
基金The National Natural Science Foundation of China (No.20371023)
文摘A new upconversion luminescence agent, 40CdF2·60BaF2·0.8ErO3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.
基金Project supported bythe Key Laboratory of Rare Earth Chemistry and Physics ,ChangchunInstitute of Applied Chemistry ,Chinese Academy of Sciences (R020202K)
文摘Nanocrystal of upconversion (UC) phosphor Ho^3+, Tm^3+ , and Yb^3+ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3+ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The result shows that Ho^3+ ,Tm^3+ , and Yb^3+ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.
基金the Foundation for the University by Educational Department of Liaoning (05L337)Key Laboratory of Rare Earth Chemistry and Physics, Chinese Academy of Sciences
文摘Y2O3: Er^3+, Yb^3+ nanoparticles were synthesized by a homogeneous precipitation method without and with different concentrations of EDTA 2Na. Upconversion luminescence spectra of the samples were studied under 980 nm laser excitation. The results of XRD showed that the obtained Y2O3:Er^3+,Yb^3+ nanoparticles were of a cubic structure. The average crystallite sizes calculated were in the range of 28-40 nm. Green and red upconversion emission were observed, and attributed to ^2H11/2,^4S3/2→^4I15/2 and ^4F9/2→^4I15/2 transitions of the ion, respectively. The ratio of the intensity of green emission to that of red emission drastically changed with a change in the EDTA 2Na concentration. In the sample synthesized without EDTA, the relative intensity of the green emission was weaker than that of the red emission. The relative intensities of green emission increased with the increased amount of EDTA 2Na used. The possible upconversion luminescence mechanisms were discussed.
基金supported by the grants from the Nature Science Foundation of Zhejiang Province (Y406309)Research Program from Science and Technology Bureau of Jinhua City (2008-1-151)
文摘Y2O3:Er^3+ films were prepared by a simple sol-gel process. The structural properties of Y2O3:Er^3+ films were characterized with X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The results indicated that the Y2O3:Er^3+ films might have high upconversion efficiency because of their low vibrational energy. Under 785 and 980 nm laser excitation, the samples showed green (^2H11/2→^4I15/2, ^4S3/2→^4I15/2) and red (^4F9/2→^4I15/2) upconversion emissions. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer process were discussed as possible upconversion mechanisms. The cross relaxation process in Er^3+ was also investigated.
基金supported by the National Natural Science Foundation of China (10474096 and 50672030)
文摘Cubic NaYF4:Yb^3+(20%)/Er^3+(1%) microspheres were synthesized by EDTA-assisted hydrothermal method. Under 980 nm excitation, ultraviolet (^4G11/2→^4I15/2), violet (^2H9/2→^4I15/2), green (^4F7/2→^4I15/2, 2H11/2→^4I15/2, and ^4S3/2→^4I15/2), and red (^4F9/2→^4I15/2) upconversion fluorescence were observed. The number of laser photons absorbed in one upconversion excitation process, n, was determined to be 3.89, 1.61, 2.55, and 1.09 for the ultraviolet, violet, green, and red emissions, respectively. Obviously, n=3.89 indicated that a four-photon process was involved in populating the ^4G11/2 state, and n=2.55 indicated that a three-photon process was involved in populating the ^4F7/2/^2H11/2/^4S3/2 levels. For the violet and red emissions, the population of the states ^2H9/2 and ^4F9/2 separately came from three-photon and two-photon processes. The decrease of n was well explained by the mechanism of competition between linear decay and upconversion processes for the depletion of the intermediate excited states.
基金financially supported by the Foundation for Universities by the Educational Department of Liaoning Province, China (No. 05L337)
文摘Y2O3:Er^3+ ultrafine phosphors with a varying Yb^3+ ion concentration were prepared by a urea homogeneous precipitation method. The results of XRD show that all the samples are of a pure cubic structure and the average crystallite sizes can be calculated as 45, 34, and 28 nm for Y2O3:Er^3+ ultrafine phosphors with Yb^3+ ion concentrations of 0, 10%, and 20%, respectively. The lattice constant and cell volume of the ultrafine phosphors decrease with enhancing Yb^3+ ion concentration. The upconversion luminescence spectra of all the samples were studied under 980 nm laser excitation. The strong green and red upconversion emission were observed, and attributed to the ^2H11/2→^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 →^4I15/2 transitions of Er^3+, respectively. The intensity of red emission increases with increasing Yb^3+ ion concentration. The effect of Yb^3+ ion concentration on the structures and upconversion luminescence mechanism were discussed.
基金Project supported bythe National Natural Science Foundation of China (50125258 and 60377040)
文摘Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate (BK7) glass containing Ce^3 + ions under focused infrared femtosecond laser irradiation. The emission spectra show that the upconversion luminescence comes from the 4f-5d transition of the Ce^3 + ions. The relationship between the intensity of the Ce^3 + emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.
基金the funding support from the Singapore Ministry of Education Academic Research Fund (AcRF Tier 3 Grant MOE2016-T3-1-004, R-397-000274-112 AcRF Tier 1 Grant R-397-000-270-114)
文摘Fluorescently encoded microbeads are in demand for multiplexed applications in different fields.Compared to organic dye-based commercially available Luminex's x MAP technology, upconversion nanoparticles(UCNPs) are better alternatives due to their large antiStokes shift, photostability, nil background, and single wavelength excitation. Here, we developed a new multiplexed detection system using UCNPs for encoding poly(ethylene glycol) diacrylate(PEGDA) microbeads as well as for labeling reporter antibody. However, to prepare UCNPs-encoded microbeads, currently used swellingbased encapsulation leads to non-uniformity, which is undesirable for fluorescence-based multiplexing. Hence,we utilized droplet microfluidics to obtain encoded microbeads of uniform size, shape, and UCNPs distribution inside. Additionally, PEGDA microbeads lack functionality for probe antibodies conjugation on their surface.Methods to functionalize the surface of PEGDA microbeads(acrylic acid incorporation, polydopamine coating)reported thus far quench the fluorescence of UCNPs. Here,PEGDA microbeads surface was coated with silica followed by carboxyl modification without compromising the fluorescence intensity of UCNPs. In this study, droplet microfluidics-assisted UCNPs-encoded microbeads of uniform shape, size, and fluorescence were prepared.Multiple color codes were generated by mixing UCNPs emitting red and green colors at different ratios prior to encapsulation. UCNPs emitting blue color were used to label the reporter antibody. Probe antibodies were covalently immobilized on red UCNPs-encoded microbeads for specific capture of human serum albumin(HSA) as a model protein. The system was also demonstrated for multiplexed detection of both human C-reactive protein(hCRP) and HSA protein by immobilizing anti-h CRP antibodies on green UCNPs.
基金supported by the National Natural Science Foundation of China (10774012,10434030)Beijing Jiaotong University Program (2007XM048,2006XM038)
文摘The upconversion emission spectra of Er^3+ doped oxyfluoride tellurite glasses excited by 808 nm laser diode (LD) were measured. The dependence of 550 nm upconversion emission on the excitation intensity was analyzed. Quadratic intensity dependence was only observed at weak excitation intensity. With increasing the excitation intensity, saturation was turned out. The experimental results were fitted to a model based on the rate equations.
基金supported by the National Natural Science Foundation of China (50372075)Shanghai Light-Tech Project (036105021)Singapore AStar SERC (052 101 0039)
文摘Cubic YAG:Yb3+, Ho3+ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials.After calcining the precipitates at 800 °C, the resultant YAG:Yb3+, Ho3+ nanocrystals were nearly spheric and the particle size was about 40 nm.Intense upconversion spectra were observed on the powder compact pumped by a 980 nm continuous wave diode laser, and green emission centered at 549 nm, red emission centered at 667 nm, and NIR centered at 760 nm were all due to two photons process, which originated from 5S2(5F4)→5I8, 5F5→5I8, and 5S2(5F4)→5I7 transitions, respectively.
基金the National Natural Science Foundation of China (50672098)the Major Sci. & Tech. Project of Fujian Province (2005HZ01-1, 2007HZ0002-2)+1 种基金the National Engineering Research Center for Optoelectronic Crystalline Materials (2005DC105003)Knowledge Innovation Program of the Chinese Academy of Sciences and the State Key Laboratory of Structural Chemistry (20080039)
文摘Nd^3+ doped transparent oxyfiuoride glass ceramic containing β-YF3 nanocrystals was prepared and the upconversion luminescence behaviors of Nd^3+ in the precursor glass and glass ceramic were investigated. Under 796 nm laser excitation, ultraviolet upconversion emissions of Nd^3+ ions at 354 nm (^4D3/2→^4I11/2) and 382 nm (^4D3/2→^4I11/2) were observed at room temperature. Power dependence analysis demonstrated that three-photon upconversion processes populated the ^4D3/2 excited state. In comparison with those of the precursor glass, the ultraviolet emissions were enhanced by a factor of 500 in the glass ceramic, which was attributed to the change in the ligand field of Nd^3+ ions and the decrease in phonon energy because of the partition of Nd^3+ ions into the β-YF3 nanocrystals after crystallization.
基金supported by the National Natural Science Foundation of China (60508014 and 50772102)Program for New Century Excellent Talents in University (NCET-07-0786)the Natural Science Foundation of Zhejiang Province (R406007)
文摘The red, green, and blue upconversion properties of Er^3+/Tm^3+/Yb^3+-codoped oxyhalide tellurite glasses were studied under 980 nm LD excitation. The intense red (657 nm), green (530 and 545 nm), and blue (476 nm) emissions were simultaneously observed at room temperature. The results showed that the mixed halide modified tellurite glass (TZFCB) had strong upconversion emissions. The effect of halide on upconversion intensity was observed and discussed, and possible upconversion mechanisms were evaluated. The intense red, green, and blue upconversion luminescence of Er^3+/Tm^3+/Yb^3+-codoped oxyhalide tellurite glasses might be a potentially useful material for developing three-dimensional displays applications.
基金Project supported by the National Natural Science Foundation of China (10474096 and 50672030)
文摘LaF3:Yb^3+ , Er^+ microcrystals were synthesized by a hydrothermal method, and then, the LaF3: Yb^3+ , Er^+ microcrystals were coated with silica. Phase identification of LaF3: Yb^3+ , Er^+ and LaF3: Yb^3+ , Er^+/SiO2 was performed via XRD. The TEM image showed that the size of LaF3: Yb^3+ , Er^+ was 150 nm and LaF3: Yb^3+ , Er^+/SiO2 presented clearly a core/shell structure with 20 nm shell thickness. The upconversion spectra of LaF3: Yb^3+ , Er^+ and LaF3: Yb^3+ , Er^+/SiO2 in solid state and in ethanol were studied with a 980 nm diode laser as the excitation source. The upconversion spectra showed that the silica shell had little effect on the properties of fluorescence of the LaF3:Yb^3+ , Er^+ microcrystals. At the same time, the green luminescence photo of LaF3: Yb3+, Er3+/SiO2 in the PBS buffer was obtained, which indicated that the LaF3: Yb^3+ , Er^+/SiO2 could be used in biological applications.
基金Project supported by the National Natural Science Foundation of China (Grant No 10074020).Acknowledgement The authors would like to thank Professor Siyuan Zhang for providing Er^3+:YAG crystal.
文摘This paper reports that the ultraviolet and visible upconversion luminescence from the ^4S3/2, ^2G9/2 and ^2P3/2 levels have been observed in Er^3+:YAG following 647.2 nm excitation of the ^4F9/2 multiple. Upconversion luminescence intensity dependence on pump power was recorded. The measured decay profiles were theoretically fitted by kinetics theory and the basically good agreements were achieved. The results indicate that some energy transfer processes proposed to explain the observed upconversion phenomena are reasonable.
基金Project supported by the Shanghai "Post-Qi-Ming-Xing plan" for Young Scientists, China (Grant No 04QMX1448) and the National Natural Science Foundation of China (Grant No 60207006).The author would like to thank Wen L,Shen Y H and Zhao Y for their help in machining and measuring.
文摘Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - (4.9 - x) AlF3(x=0, 0.5, 1.0, 1.5, 2.0) in tool fraction, Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm^3+: ^1D2 →^3F4, ^1G4 →^3H6, ^1G4 →^3F4, and ^3H4 →^3H6, respectively, are observed. Due to the sensitization of Yb^3+ ions, all the upconversion luminescence intensities are enhanced considerably with Yb^3+ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.
基金the National Natural Science Foundation of China(No.2 0 0 730 16 and 6 0 2 710 2 0 ) ,state 86 3Projects(No.2 0 0 2 AA 30 2 2 0 3) and state 973Projects(No.G19990 6 4 5 0 4 )
文摘Erbium, Ytterbium-codoped ZrO 2 nanoparticles(ZrO 2∶Er 3+ ,Yb 3+ ) were prepared by the sol-emulsion-gel technique. The purpose of the present study is the application of upconversion phosphor in the biological label. In order to make out the mechanism of upconversion under 980 nm excitation the 488 nm pump was used. The influence of temperature on the crystallite phase was studied. The results confirm the upconverted mechanism in ZrO 2∶Er 3+ ,Yb 3+ nanocrystals is due to an energy transfer upconversion(ETU).
基金Supported by the National Nature Science Foundation of China under Grant No 10374086, and the 0ne Hundred Talents Project of Chinese Academy of Sciences.
文摘The upconversion luminescence and dynamics in Er^3+ /Yb^3+ codoped nanocrystalline yttria (7-65 nm) are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the green emission of ^2H11/2/^4S3/2 in nanoparticles with lower concentration of Yb^3+ result from a two-photon excitation, In nanocrystals with higher Yb^3+ concentration, the red emissions from a two-photon excitation, while the green emissions from a three-photon excitation, The luminescence dynamics indicates that as the particle size decreases, both the rise and the decay time constants become shorter, As the size decreases to several nanometres, the rise process nearly disappears, suggesting that the upconversion luminescence originates mainly from self-excitation of Er^3+, instead of the energy transfer of Yb^3+→ Er^3+.
文摘Intense upconversion emissions of YLiF 4∶Er 3+ synthesized by hydrothermal method were obtained. The upconversion intensity decreases with the increase of environment temperature. In different temperature, the upconversion mechanism is different. At room temperature, the green upconversion mechanism is the combination of two photon process and three photon process, and the red upconversion mechanism is two photon process.