Development of red-emitting Ba2LaSbO6:Mn4+ phosphors for latent fingerprint detection

Latent fingerprints provide crucial affirmations of identity in forensic science. However, they are microscopic. In this study, novel fluorescence materials, Ba₂LaSbO₆:Mn⁴⁺ (BLSO:Mn⁴⁺) phosphors, were developed by a sol–gel method for the fluorescence imaging of latent fingerprints. The structural properties of the phosphors were investigated by powder X-ray diffraction (XRD) and its Rietveld refinement analyses, and transmission electron microscopy and scanning electron microscopy techniques. The photoluminescence properties of the BLSO:Mn⁴⁺ phosphors were evaluated comprehensively by recording the emission, excitation, and decay curves. The BLSO:Mn⁴⁺ phosphors provide a high-intensity red emission at 677 nm under 350 nm excitation caused by the ²E_g→⁴A_2g transition of Mn⁴⁺. The optimum concentration of Mn⁴⁺ in the BLSO host was determined to be ~0.2 mol%. The calculated Commission International de L'Eclairage (CIE) chromaticity coordinates (0.716, 0.283) of the emission from the BLSO:Mn⁴⁺ phosphor are located in the pure red region of the CIE 1931 diagram. The red-emitting BLSO:0.2Mn⁴⁺ phosphor was used as a fluorescence imaging powder for visualizing latent fingerprints on various substrates with high resolution, high contrast, and high efficiency, as well as good selectivity.     

Hexagonal sodium yttrium fluoride mesocrystals: One-pot hydrothermal synthesis,formation mechanism and multicolor up-/down-converted luminescence for anti-counterfeiting and fingerprint detection

Currently, a precise architecture manipulation of mesocrystals with controllable morphology and tunable size remains a huge challenge and is highly desired for their practical applications. Here, we develop a facile one-pot strategy for the direct synthesis of uniform and monodispersed β-NaYF₄ mesocrystals with cantaloupe-like shape and adjustable dimension. To investigate the formative mechanism of β-NaYF₄ superstructures in depth, the evolution processes for the crystal structure and morphology of β-NaYF₄ mesocrystals under different experimental conditions have been systematically researched and discussed. A series of experimental results demonstrate that intrinsic crystallographic structure and external factors govern the crystal growth process of hexagonal-phased NaYF₄. The processes of dissolution-renucleation, anisotropic growth, subsequent oriented attachment and self-assembly are believed to be responsible for the formation of cantaloupe-shaped β-NaYF₄ mesocrystals. Moreover, the luminescence properties of β-NaYF₄:RE³⁺ (RE = Ce, Tb, Eu, Yb, Tm and Ho) mesocrystals are also studied and efficient multicolor upconverting and downshifting emissions can be easily realized. As a proof of concept experiment, the as-synthesized β-NaYF₄:RE³⁺ phosphors are employed to demonstrate their promising applications in anti-counterfeiting and fingerprint identification.     

A highly intense double perovskite BaSrYZrO5.5: Eu3+ phosphor for latent fingerprint and security ink applications

A novel double perovskite BaSrYZrO_5.5:Eu³⁺ red-emitting phosphor was synthesized and characterized by XRD, SEM and PL analyses. The structure of the prepared phosphor was confirmed through JCPDS as well as Rietveld refinement analysis. The present phosphor shows an intense red emission at 613 nm when excited by 394 nm. The CIE colour coordinates value of BaSrYZrO_5.5:Eu³⁺ (9 mol%) phosphor is found to be (0.6181, 0.3783) and it has high colour purity of 99.1%. The 613 nm transition integrated intensity of the present phosphor is 4.44 times higher compared to the commercial red phosphor. The thermal stability and Quantum yield of optimized BSYZ:Eu³⁺ (9 mol%) phosphor were also calculated. The BSYZ:Eu³⁺ phosphor results can be employed as an efficient red component in latent fingerprint detection and anti-counterfeiting applications.     

A turn-on fluorescent solid-sensor for Hg(II) detection

A rhodamine organosilane derivative (Rh-UTES) has been obtained by one-pot synthesis. The chemical structure of Rh-UTES was confirmed by nuclear magnetic resonance (NMR) and infrared (FTIR) techniques. To obtain an inorganic-organic hybrid sensor, Rh-UTES was covalently immobilized on a porous silicon microcavity (PSiMc) via triethoxysilane groups. The attachment of the organic derivative into PSiMc was confirmed by FTIR, specular reflectance, and scanning electron microscopy (SEM). The optical performance of Rh-UTES receptor for Hg²⁺ detection was investigated by fluorescent spectroscopy and microscopy. Upon the addition of increasing amounts of Hg²⁺ ions, a remarkable enhancement in emission intensity was produced in both systems. In the solid phase, an increase of integrated fluorescent emission of 0.12- and 0.15-fold after Hg²⁺ receptor coordination was observed. The light harvesting capability of PSiMc devices allowed obtaining an enhanced fluorescent emission after Rh-UTES immobilization (277-fold). The fluorescence microscopy of hybrid PSiMc sensor provided an optical qualitative test for Hg²⁺ detection.     

海洋溢油化学指纹分析鉴定方法探讨

石油资源分布不均推动石油勘探和运输规模不断扩大,溢油事故日益增多,包括井喷,船舶漏油等,带来环境损害评估等问题。油指纹分析鉴定通过研究油品风化周期,推断溢油对环境的影响时间,通过生物毒性实验判断对环境影响程度。为事故调查处理提供科学依据,包括缩小调查对象范围,确定溢油来源种类。针对当前溢油鉴定中的问题进行研究,表明油品混合可能存在化学变化,扩大混合前油品特征比值差异,正构烷烃特征比值与萜烷类特征比值相同,可能为不同油品,说明多采集油品特征信息是溢油鉴定的重要基础。     

The use of fluorescent probes for the detection of under-film corrosion

An inexpensive and practical method for detecting under-film aluminium corrosion using a hand-held UV inspection lamp is described. A novel fluorescent probe for under-film iron corrosion is demonstrated. Studies of light transmission and ion transport through three types of paint film show polyester to be the best barrier to ions and epoxy to be the most transparent in the near UV.     

Synthesis of Li+-ion activated NaYF4: Er3+/Yb3+ phosphors via a modified solid-state process for latent fingerprint detection

Li⁺-ion codoped NaYF₄: Er³⁺/Yb³⁺ phosphors (β-NaYF₄) with a hexagonal structure were synthesized via a modified solid-state route. High-speed planetary ball milling and solid-liquid mixing were simultaneously used to overcome the drawbacks of high synthesis temperatures in conventional routes. A pure β-NaYF₄ phase was obtained through calcination at 600?°C for 3?h. Increases in the codoping content of Li⁺ ion caused a slight shift in X-ray diffraction peak positions toward high angles owing to the distortion of the local crystal field. Field emission scanning electron microscope images showed agglomerated spherical particles of approximately 0.7?µm with narrow size distribution. The upconversion properties of β-NaYF₄ codoped with Li⁺-ion were explored. Two emission bands in the green regions (520?nm and 545?nm) and one emission band in the red region (615?nm) were observed owing to the ²H_11/2→⁴I_15/2, ⁴S_3/2→⁴I_15/2, and ⁴F_9/2→⁴I_15/2 transitions of Er³⁺, respectively. Codoping with 6?mol% Li⁺ increased the upconversion intensity by three times, which was explained using the energy level diagram. The present phosphors with improved upconversion properties were utilized for latent fingerprint detection on smooth surfaces of regularly used polymer sheets, glass substrates, and compact discs. Using the present phosphors, the base elements with three-level features, such as sharp ridges, valleys, ridge flow, bifurcation, ridge shapes, and dots, were observed on all hydrophilic and hydrophobic surfaces. The prepared phosphors exhibited promising characteristics to detect the features of fingerprint impression for individual identification in forensic applications.     

A polymer based fluorescent sensor for Zn detection and its application for constructing logic gates

A polymer-based fluorescent sensor was synthesized by polymerization of (S)-6,6′-dibutyl-3,3′-(di-5-salicylde-ethynyl)-2,2′-binaphthol (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via nucleophilic addition-elimination reaction. The responsive optical properties of the polymer on transition metal ions were investigated by fluorescence and UV-vis spectra. The polymer (1.0 × 10⁻⁵ mol/L in THF) could emit fluorescence at 550 nm and exhibit high selectivity for sensing Zn²⁺ with 36.1-fold fluorescence enhancement. Three logic gates were designed according to the different fluorescence responses of this polymer sensor to Zn²⁺ and Cu²⁺.     

Ternary type BaY2ZnO5: Eu3+ deep-red phosphor for possible latent fingerprint,security ink and WLED applications

Pc-WLEDs are considered to play a spectacular role in future generation light sources in view of their outstanding energy efficiency. In this regard, Eu³⁺ activated BaY₂ZnO₅ phosphor was prepared and investigated by XRD, PL and SEM analyses. Rietveld refinement analysis was carried out to confirm the structure of the synthesized phosphor. The prepared phosphor shows an intense red emission around 627 nm under excitation by near UV light. The ⁵D₀-⁷F₂ transition intensity of the prepared phosphor is three times higher compared to the commercial (Y,Gd)BO₃:Eu³⁺ red phosphor. The CIE colour coordinates of BaY₂ZnO₅:Eu³⁺ (9mol%) phosphor corresponds to be (0.6169, 0.3742) and it has a high 97.9 % colour purity. The obtained results reveal the utility of BaY₂ZnO₅:Eu³⁺ phosphor as an efficient red component in WLEDs, anti-counterfeiting and fingerprint detection applications.     

Trap distribution and photo-stimulated luminescence in LaSrAl3O7:Eu2+ long-lasting phosphors for optical data storage

Here, a green emission persistent luminescent phosphor LaSrAl₃O₇:Eu²⁺ which is chargeable by UV light, was synthesized by solid-state reaction method. Elemental mapping and fluorescence microscopy photoluminescence of the sample demonstrated the homogeneous distribution of La, Sr, Al, O, and Eu in the phosphor. Rietveld refinement shows that the as-prepared sample belongs to the tetragonal crystalline structure with space group of P42₁m. The Eu²⁺:5d-4f broad persistent luminescence with maximum emission peaking at 518 nm can be effectively obtained after irradiating in the UV light. A series of excitation temperature-dependent thermoluminescence measurements were conducted to gain some insight into the information of traps. Additionally, to verify its feasibility of optical data storage, specific information letters were encoded on the LaSrAl₃O₇:Eu²⁺ phosphor films using the laser of 405 nm, then the stored information could indeed be read out by thermal stimulation as expected. Meanwhile, NIR photo-stimulated red persistent luminescence was also obtained, which holds great potential for optical information storage. Finally, combined with the experimental and density functional theory calculation results, we proposed a tentative schematic diagram to account for the PersL and photo-stimulated persistent luminescence mechanism in LaSrAl₃O₇:Eu²⁺ phosphor.     

A novel far-red phosphors Li2ZnTi3O8:Cr3+ for indoor plant cultivation:Synthesis and luminescence properties

A novel far-red phosphors Li₂ZnTi₃O₈:Cr³⁺ were successfully synthesized via the conventional solid-state method. The structural characteristics, luminescence properties and concentration quenching of the Li₂ZnTi₃O₈:Cr³⁺ phosphors were investigated systematically. Under the excitation at 360 nm and 468 nm, the Li₂ZnTi₃O₈:Cr³⁺ phosphors displays the emission spectra in the range from 600 nm to 850 nm. The far-red emission centered at 735 nm was attributed to the spin-forbidden ²E→⁴A₂ transition of Cr³⁺ ions. The research results of this paper indicate that the phosphors Li₂ZnTi₃O₈:Cr³⁺ has prospective applications in indoor plant cultivation.     

适用于催化剂和发光材料研究的并行合成和高通量表征技术

介绍了作者课题组近年来所发展的适用于催化材料和发光材料研究的并行合成和高通量表征技术,以及在新材料筛选方面开展的工作。在并行合成方面包括组合喷射合成仪、微型阵列式溶液燃烧技术以及结合四元掩模和连续掩模的磁控溅射和脉冲激光沉积系统;高通量表征部分包括真空紫外荧光照相系统和组合光谱扫描仪、红外热成像筛选装置和同步辐射红外光谱成像系统。最后,简要介绍了利用所发展的组合技术在稀土聚合物敏化发光材料、真空紫外荧光材料以及可见光响应光催化材料方面开展的工作。     

CdTe/CdS核壳量子点的合成和指纹检测研究

本文用水相合成法分别合成了巯基乙酸和谷胱甘肽修饰的CdTe/CdS量子点,讨论了不同反应时间对量子点大小的影响。发现随着回流时间延长量子点的粒径逐渐变大,其荧光发射及吸收峰位置也发生相应的红移,从而量子点发光颜色呈现递变。鉴于量子点这一优良的发光特性,将其应用于光滑客体表面潜在指纹的显现,结果表明此方法灵敏度高,简便,快速。     

Design of Eu2+-activated broadband orange-emitting phosphors with excellent luminescent performance for warm WLEDs

We report orange-emitting Sr₈La_0.5Na_0.5Mg_1.5(PO₄)₇:Eu²⁺ (SLNMPO-0.5:Eu²⁺) and Sr₇LaNaMg_1.5(PO₄)₇:Eu²⁺ (SLNMPO-1:Eu²⁺) phosphors with broad emission bands covering from 450 to 800 nm. The phosphors can be excited by n-ultraviolet and blue light efficiently. Their crystal structure, diffuse reflection spectra, photoluminescence (PL) spectra, fluorescence decay curves and thermal stability were investigated systematically. Under the excitation of 365 and 400 nm, SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺ both exhibit better PL properties and contain more red emissions than SMPO:Eu²⁺. CIE coordinates of SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺ under 365 nm excitation are (0.460, 0.497) and (0.457, 0.494), respectively. Furthermore, high-quality warm white light can be generated by fabricating warm white light-emitting diode (WLED) devices with 370 nm LED chips, BaMgAl₁₀O₁₇:Eu²⁺ commercial blue phosphor and orange-emitting SLNMPO-0.5:Eu²⁺ (or SLNMPO-1:Eu²⁺) phosphor. The correlated color temperature, R_a and color coordinates are 3880 K, 94.05, (0.3895, 0.3922) and 3736 K, 91.73, (0.4005, 0.4078) for the fabricated WLED devices with SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺, respectively. The excellent performances indicate that SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺ have great potential to be attractive candidates in the application of warm WLEDs.     

Novel cyan-emitting KBaScSi2O7:Eu2+ phosphors with ultrahigh quantum efficiency and excellent thermal stability for WLEDs

Owing to the conventional phosphor-converted white LEDs (pc-WLEDs) generally suffer from blue-green cavity, thus, developing an appropriate phosphors covering both the blue and green regions in their emission spectra are very urgent. Herein, a novel Sc silicate phosphor, KBaScSi₂O₇:Eu²⁺ (KBSS:Eu²⁺), has been successfully designed and prepared via a solid-state reaction. The crystal structure, luminescent properties, thermal quenching, quantum efficiency as well as its application in UV-pumped WLEDs have been investigated systematically. The KBSS:Eu²⁺ phosphor exhibits a strong and broad excitation band ranging from 290 to 450 nm, and gives a sufficient cyan emission of 488 nm with a full-width half-maximum (FWHM) of 70 nm, which filled the blue-green cavity. Importantly, the optimized KBSS:Eu²⁺ phosphor possesses an ultrahigh quantum efficiency (QE) up to 91.3% and an excellent thermal stability retaining 90% at 423 K with respect to that measured at room temperature. Finally, the as-fabricated UV-based WLEDs device, with only coupled the mixture of KBSS:Eu²⁺ cyan phosphor and CaAlSiN₃:Eu²⁺ red ones to a commercial 365nm UV chip, exhibits a satisfactory color-rendering index (Ra = 88.6), correlated color temperature (CCT = 3770K), and luminous efficiency (LE = 21 lm/W).     

Glass-ceramic phosphors for solid state lighting: A review

Solid state lighting, including phosphor converted light-emitting diodes (LEDs) and laser diodes (LDs), have released high demand to develop thermally stable phosphors. For this purpose, inorganic glass-ceramics (GCs) embedded with phosphor particles can act as competitive candidates. They are superior to traditional phosphors or resin/silica composites through successfully overcoming thermal aging and color temperature drifting problems and simultaneously maintaining high luminescent efficiencies. Inorganic GC phosphors can be classified into devitrified glass-ceramics, PiG (Phosphor-in-Glass) and sintered glass-ceramics. This review summarized the recent progress on LED/LD GC phosphors from the aspects of design principles, synthesis methods, microstructure-property relationships and their application studies. In addition, some challenging issues (e.g., crystallization behavior of luminous phase in glass, corrosion behavior of phosphor by glass matrix) are also discussed in detail. Significant issues of glass-ceramics packed LED/LD, such as luminescence efficiency, chromaticity, correlated color temperature and color gamut, are sorted out as well. Potential research directions are further suggested for not only developing new glass-ceramic phosphors but feeding upon various practical application.     

Electrospinning,optical properties and white LED applications of one-dimensional CaAl12O19:Mn4+ nanofiber phosphors

Non-rare-earth, red-emitting CaAl₁₂O₁₉:Mn⁴⁺ nanofiber phosphors have been successfully prepared by an electrospinning technique followed by an annealing process. The as-prepared precursor fibers have smooth surfaces with an average diameter of 5 µm. After annealing at high temperature, the diameter of the fibers gradually reduces due to the decomposition of the organic polymers. The photoluminescence and crystalline properties of the fibers were investigated as a function of Mn⁴⁺ concentration and the annealing temperature. Under ultraviolet and blue light excitation, CaAl₁₂O₁₉:Mn⁴⁺ exhibits a characteristic red emission at 655 nm with three satellite peaks due to the ²E→⁴A₂ transition of Mn⁴⁺. The highest PL intensity is achieved at a 0.5% Mn⁴⁺ concentration and a firing temperature of 1400 °C. In comparison to CaAl₁₂O₁₉:Mn⁴⁺ prepared by a usual solid-state reaction, the luminescence of the as-prepared nanofiber phosphors in the present work has been strongly enhanced by optimizing the morphology and improving the crystallinity and phase purity. The absorption band in the blue region and a bright emission in the red region make the CaAl₁₂O₁₉:Mn⁴⁺ nanofiber phosphor a candidate for achieving high color rendering in YAG:Ce-based WLEDs. A warm WLED with a high CRI of 88.5 at a CCT of 4553 K has been successfully achieved by coating YAG:Ce with CaAl₁₂O₁₉:Mn⁴⁺ nanofiber phosphors on blue InGaN chips.     

Luminescence properties of novel Eu3+-doped tantalate NaCaTiTaO6 red-emitting phosphors for solid-state lighting

A novel tantalate red-emitting phosphors NaCa_1-xEu_xTiTaO₆ (x = 0.02-0.50) is synthesized via the traditional solid-state reaction sintering. The photoluminescence properties, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal stability are characterized in detail. Photoluminescence spectra show strong red emission monitored at 614 nm at λ_ex = 395 nm. The spectral properties exhibit excellent color purity and chromaticity coordinate (CIE) characteristics. White light-emitting diodes (w-LEDs) device are fabricated by the prepared phosphors and show high quality of color-rendering index. The investigated results suggest that the Eu³⁺-doped NaCaTiTaO₆ phosphors can be as potential substitute red phosphors for w-LEDs.     

Preparation and luminescence of SrAl2O4: Eu2+,Dy3+ phosphors coated with maleic anhydride

In this paper, maleic anhydride is directly coated on the surface of SrAl₂O₄: Eu²⁺, Dy³⁺ (SAO‐ED) phosphors by an interfacial coordination chemistry method. Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectra (XPS), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) methods are used to characterize the coating. The experimental result shows that a dense coating layer is consisting of maleic anhydride coordination with metal ions on the surface of the phosphors and the coating process does not destroy the crystal structure of the phosphors. It is also found that the introduction of maleic anhydride does not change the excitation and emission spectra of SAO‐ED phosphors, but decreases the luminous intensity, which is verified by the photoluminescence (PL) measurement. Afterglow delay curves show that the initial brightness of coated SAO‐ED phosphors decreases, but the afterglow decay rate of coated phosphors is slower than that of uncoated phosphors after they both are immersed into water for one month. This indicates that the coating layer protects the phosphors and the crystal structure of coated phosphors in water was not destroyed.     

指纹特征-毛细管气相色谱法定性检测大米中矿物油

针对皂化法鉴定矿物油的不足,利用毛细管气相色谱仪,结合矿物油组成特点建立了大米中矿物油气相色谱指纹定性检测方法,通过比较大米提取物的色谱峰组成来对大米是否掺加矿物油进行定性,方法定性可靠直观,应用到大米的检测中效果良好。