Visualization Of Fingerprints Research Articles

Pyridinium‐Based Schiff‐Base Fluorescent Chemosensor for Sequential Detection of Al3+ Ions and TNP: Applications in Cell Imaging and Latent Fingerprint Visualization

AbstractA fluorescent pyridinium‐based chemosensor (E)‐1‐(2‐(3‐hydroxy‐4‐((pyridin‐2‐ylimino) methyl) phenoxy) ethyl) pyridin‐1‐ium bromide (BzPySB) was synthesized and characterized using various spectroscopic techniques. The chemosensing potential of BzPySB was explored using UV‐vis and fluorescence spectroscopy in the aqueous medium. The turn‐on fluorescence behavior was observed for BzPySB in the presence of Al3+, while other metal ions were non‐responsive. The B−H and Job′s plot confirmed the 1 : 1 stoichiometric ratio of the BzPySB and Al3+. The in situ generated complex BzPySB‐Al3+ offered selectivity toward TNP via fluorescence turn‐off phenomena with high Ksv and LOD values. The “off‐on‐off” sensing mechanism was elucidated through 1H NMR, mass spectrometry, and DFT calculations. The probe also detected Al3+ in plant and MCF‐7 cells, highlighting its potential in biological systems. Moreover, BzPySB exhibited solid‐state luminescent properties credited to weak π‐π interaction, leading to its successful application in the visualization of latent fingerprints.

Curcumin/kaolin composite for advanced latent fingerprint imaging with fluorescence quantification.

Latent fingerprints (LFPs) are invisible impressions that need to be developed before being used for criminal investigation; however, existing fingerprint visualization techniques face challenges, such as complex preparation and poor contrast. To advance practical fingerprint detection, green-emissive micron-sized curcumin/kaolin composites were synthesized via a facile and cost-effective one-step physical cross-linking method, which exhibited unprecedented performance in developing diversified marks, including LFPs, knuckle prints, palm prints, and footprints, with clear three-level details on various substrates. Notably, the powders successfully developed LFPs that were aged for 30 days and even up to 100 days, meeting the stringent requirements for comprehensive forensic application. Afterward, a novel method, termed Fingerprint Fluorescence Intensity Ratio (FFIR), was developed to quantify the contrast between fingerprint signals and background noise and to compare the efficacy of full-color developing agents. Compared with the existing grayscale conversion strategy, the proposed FFIR method achieved tunable multi-color fingerprint image enhancement for the first time, which helped to eliminate background fluorescence interference and improved visual perception. The feasibility of FFIR and its sensitivity in tracking image capture parameters were demonstrated by the established mathematical model. Hence, the newly synthesized modified composites and the mathematical model-validated method demonstrate profound practical significance in comprehensive fingerprint imaging.

An investigation of the potential of rhodamine B hydrazide as a fluorescent probe for enhancing latent fingerprints

A series of novel rhodamine B hydrazide derivatives were synthesized by refluxing rhodamine B hydrazide with various aromatic aldehydes, including 3-nitrobenzaldehyde, 4-nitrobenzaldehyde, 4-chlorobenzaldehyde, 4-hydroxybenzaldehyde, cinnamaldehyde, piperonal, and veratraldehyde. The resulting hydrazones were purified and characterized through techniques including melting point determination, UV–Vis spectroscopy (λmax ranging from 245 to 555 nm), infrared (IR) spectroscopy, and proton nuclear magnetic resonance (NMR) spectroscopy. The derivatives exhibited strong fluorescence with enhancements up to 90 % at optimized wavelengths, facilitating their use in latent fingerprint visualization. Yields of the purified derivatives exceeded 85 %, with melting points in the range of 172–188 °C. Notably, certain derivatives enhanced latent fingerprint contrast by up to 60 % on glass surfaces, indicating significant potential in forensic applications. This study demonstrates a cost-effective and environmentally friendly synthesis method that provides high yields of pure fluorescent agents suitable for forensic science.

Postmortem fingerprint identification: A novel adaptive approach to the transillumination technique using moistened black volcano powder for fragile epidermal tissue.

Postmortem identification through fingerprints often encounters significant challenges, particularly with damaged epidermal tissue, due to factors such as carbonization, putrefaction, mummification, or saponification. Traditional techniques frequently fall short in cases involving fragile skin, which complicates the collection of clear fingerprint impressions. This study presents and evaluates an adaptive modification of the transillumination technique, integrating it with moistened black volcano powder to enhance fingerprint recovery from compromised postmortem tissue. A retrospective comparative analysis was conducted on 55 cases processed at the Ricardo Gumbleton Daunt Institute of Identification, São Paulo, Brazil, from January 2012 to May 2022. Of these, 12 cases with both pre- and post-treatment records were selected, totaling 28 distal phalanx samples. The proposed technique involved applying moistened black volcano powder to the epidermis, followed by transillumination and direct photography. The enhanced technique demonstrated a significant improvement in fingerprint quality. Qualitative analysis revealed that all samples treated with moistened black volcano powder clearly presented visible ridges and minutiae, whereas four samples treated with traditional transillumination alone were insufficient for minutia marking. Quantitative analysis indicated that 75% of the samples scored +2 (greater minutiae details and contrast), with an additional 25% scoring +1 (slightly better minutiae details and contrast). The combined use of transillumination and moistened black volcano powder significantly improves the visualization of postmortem fingerprints, providing a reliable method for forensic identification in cases with fragile or compromised epidermal tissue from putrefied or carbonized skin. This technique generates high-resolution fingerprint images that are suitable for database comparison and forensic analysis.

Development of highly thermal-stable blue emitting Y4Al2O9:Bi3+ phosphors for w-LEDs, fingerprint and data security applications

A new blue-emitting Y4Al2O9:Bi3+ (YAO:Bi3+) phosphor is synthesized using the solution combustion method with mushroom extract as a binder. Its structural properties, concentration effects, temperature-dependent luminescence, and performance in LED devices are thoroughly investigated. Upon excitation at 367 nm, a strong blue light emission at 423 nm is observed, attributed to the 3P1→1S0 transition of Bi3+. The quantum efficiency reached approximately 63.5 %. The CIE diagram shows that the emission colour falls within the intense blue region, achieving a colour purity (CP) of 94 %. YAO:Bi3+ exhibits strong absorption in the near-ultraviolet range (330–400 nm), making it suitable for LEDs powered by near-ultraviolet chips. A thermal quenching experiment revealed an activation energy (Ea) of 0.323 eV, indicating that this YAO:Bi3+ phosphor possesses good thermal stability. This study showcases the use of YAO:Bi3+ phosphor in encapsulated LED devices. The device’s Commission Internationale de l’Éclairage (CIE) coordinates are (0.325, 0.310), with a high colour rendering index (CRI) of 94.70 and a low correlated colour temperature (CCT) of 5915 K at a current of 120 mA. These properties indicate that this phosphor is suitable for developing white LED devices powered by near-ultraviolet chips. The optimized YAO:Bi3+ phosphor is employed to enhance the detection of Level I-III fingerprint (FP) details with high resolution and contrast, showing effective visualization of latent fingerprints (LFPs) on various substrates. Furthermore, it is used as a model for developing fluorescent ink, which is applied to different media. The results suggest that YAO:Bi3+ phosphor has significant potential for applications in w-LEDs, advanced forensics, and anti-counterfeiting ink technologies.

Exploring the potential of BaLa₂ZnO₅ doped with individual rare-earth ions (Ce³⁺, Er³⁺, Eu³⁺) for w-LEDs, latent fingerprints, and anti-counterfeiting applications

The novel Ce3+/Er3+/Eu3+ (1 mol %) activated BaLa2ZnO5 (BLZO) nanophosphors (NPs) were synthesized via a combustion method. Micro-morphology, phase purity, luminescence characteristics, and crystallographic structure of the material are examined. The NPs with the subsequent characteristics exhibit notable emission under 349, 378, and 395 nm excitation: BLZO:Ce3+, BLZO:Er3+, and BLZO:Eu3+ at 400, 550, and 615 nm, respectively. The decay curves of each sample are recorded for specific excitation and emission wavelengths respectively. All the decay curves are well-fitted with single exponential function. The observed average decay time is 1.563, 1.165 and 0.949 ms. In addition, photometric studies including Chromaticity International d’Eclairage (CIE), correlated colour temperature (CCT) and colour purity (CP) are performed. The phosphor demonstrated good contrast, minimal background interference, and great resolution when applied to several substrates in latent fingerprints (LFPs). Therefore, the phosphor provides a material that shows promise for latent fingerprint visualization. The feasibility of the Anti-counterfeiting (AC) function of BLZO: Ce3+/Er3+/Eu3+ phosphor is investigated on a diverse of surfaces using both screen-printing and handwriting techniques. By means of aging, heat treatment, and water immersion treatment, the durability of all three security inks has been investigated. These diverse characterization results indicate that the hypothesized Ce3+/Er3+/Eu3+ activated BLZO phosphor has potential applications in solid-state lighting for white light emitting diodes (w-LEDs), LFPs and AC techniques.

Versatile organosilicone porous materials for the detection of nitroaromatics and the visualization of fingerprints

Achieving explosive detection and fingerprints visualization at the same time is of great significance. Towards this end, based on the cage structure and multiple reaction sites of octavinyl polyhedral oligomeric silsesquioxane (OVS), a series of multifunctional silicone porous materials OVSBs and OVSTs were designed and synthesized with 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-triazine. These porous materials have narrow pore size distribution, high specific surface area and pony-sized that smaller than 5 nm. The micropore volume ratio of porous materials can be changed by regulating the molar ratio of OVS to functional compounds. OVSB-2 shows excellent adsorption capacity for fluorescent dyes due to its highest specific surface area and high micropore volume ratio. OVSB-2 also has superior fluorescence characteristic, which can quickly detect nitroaromatic compounds within 20 s. This work provided a new method for expanding the application of silicone mesoporous materials in explosive detection and fingerprints visualization simultaneously.

Colorimetric and fluorimtric microenvironment responsivity of oxazolidine in solvatochromic latex nanoparticles: Versatile intelligent polymeric materials with advanced applications

Oxazolidine, a new category of stimuli-chromic dyes, has displayed a wide range of responsivities, such as halochromism, solvatochromism, ionochromism, and hydrochromism. The optical properties of oxazolidine molecules can be influenced notably by the polarity of solvent, media, and polymer nanoparticles. In this study, multi-functionalized acrylic latex nanoparticles containing different polar functional groups such as amide, amine, acid, hydroxyl, epoxide, and long-chain ester were synthesized by one-pot emulsion copolymerization. Prepared latex nanoparticles have a mean particle size in the range of 45–170 nm and spherical or non-spherical (anisotropic) morphologies depending on the polarity of functional groups. To prepare multi-color photoluminescent latex nanoparticles and investigation of solvatochromism in both colloidal solution and solid phase, as prepared multi-functionalized latex nanoparticles were modified physically with an oxazolidine derivative (5 wt%). Investigation of the solvatochromism of the oxazolidine in colloidal solution and solid phase indicated that the media is the main effective parameter for solvatochromism in colloidal solution. In the case of solid-state solvatochromism, the optical properties of oxazolidine were influenced significantly by the polarity of functional groups, because the interactions of oxazolidine molecules with functional groups of latex nanoparticles is the main parameter that influenced the solvatochromism. The solvatochromic properties of oxazolidine in solid polymer powders are useful for developing multi-color photoluminescent materials with advanced applications in the dual-mode visualization of latent fingerprints (LFPs), anticounterfeiting solid inks, and organic light-emitting diodes (OLEDs). Results displayed potential applications of multi-color polymer powders for the detection of LFPs under visible light and UV-light irradiation, for printing of optical security tags, and construction of OLEDs. The presented study introduces a new category of multi-color solid photoluminescent nanomaterials with multiple applications using solvatochromic properties.

Fluorescent Carbon Dots for Improved Visualization of Latent Fingermarks after Cyanoacrylate Fuming

Fluorescent Carbon Dots for Improved Visualization of Latent Fingermarks after Cyanoacrylate Fuming

Solid-state solvatochromism of oxazolidine in multi-functionalized copolymer nanoparticles: Development of advanced materials with multi-color fluorescence

Investigating the solvatochromism of stimuli-chromic compounds such as oxazolidine in polymer matrices with various polarities or functionalities is a unique approach to developing advanced materials for anticounterfeiting, sensor, optoelectronic, and displayers. In a novel strategy, multi-functionalized copolymer nanoparticles were synthesized by copolymerization of methyl methacrylate (MMA) with various functional comonomers in emulsion media for post-polymerization modification with oxazolidine and investigation of its solvatochromism in both colloidal solution and solid phase. The particle size and morphology of nanoparticles were influenced significantly by the polarity of functional groups, and the morphology evolution from sphere to anisotropic shapes was observed by increasing the polarity of functional groups. Investigation of oxazolidine solvatochromism in colloidal solution and solid polymer powders indicated different mechanisms for solvatochromism, in which the polarity of media is the main effective parameter in colloidal solution and the polarity of functional groups in the polymer structure is the main effective parameter in solid polymer phase. The solvatochromism of oxazolidine was confirmed by observed red shift and blue shift in UV–Vis and fluorescence spectra, in which the intensity of absorbance and emission peaks was changed as a function of the polarity of functional groups. Solvatochromic photoluminescent polymer nanoparticles were used for several advanced applications such as solid anticounterfeiting inks to information encryption, dual-mode visualization of latent fingerprints, and also development of organic light-emitting diodes (OLEDs). For the first time, the results indicate a significant effect of polymer chain local polarity induced by functional groups on the tuning of optical properties of the oxazolidine by the solid-state solvatochromic phenomenon. Solvatochromism of oxazolidine in functionalized polymer nanoparticles is an interesting approach to developing novel intelligent materials that have advanced applications in different fields such as anticounterfeiting and information encryption, optoelectronic, polarity sensor, and visualization of latent fingerprints.

A novel highly thermally stable phosphor powder Ba2LuSbO6: Eu3+ for latent fingerprint visualization

In modern forensic science, fingerprints are critical evidence due to their uniqueness and difficulty to replicate. However, it is challenging to observe and identify some latent fingerprints (LFP), because alternative processing methods for recognition are often required. The use of Eu3+-doped phosphors, which emit red-orange light, presents an effective approach for enhancing the visibility of LFP. Eu3+-doped Ba2LuSbO6 (BLSO) phosphors were synthesized using a high-temperature solid-state method, aiming to improve the recognition of LFP for enhanced fingerprint identification. The phase structure of the fluorescent powder samples was analyzed through X-ray diffraction (XRD) combined with Rietveld refinement, as well as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photoluminescence spectra of Ba2LuSbO6: xEu3+ phosphor samples exhibit orange-red emission peaks at 595 and 618 nm when excited by 250 nm deep ultraviolet light. Concentration quenching is observed at a doping concentration of 20 mol%. The Ba2LuSbO6: 0.2Eu3+ phosphor sample demonstrates exceptional thermal stability, with value of 92.50% at 423 K. The quantum efficiency of the Ba2LuSbO6: 0.2Eu3+ phosphor sample was evaluated using an integrating sphere, yielding an IQE of 79.34%. In order to visualize latent fingerprints (LFPs), hydrophilic BLSO: 0.2Eu3+ phosphors were transformed into hydrophobic BLSO: 0.2Eu3+@OA phosphors through a coating of oleic acid (OA). The BLSO: 0.2Eu3+@OA phosphor proves capable of generating dependable LFP fluorescence images with superior contrast and resolution. These findings underscore the significant potential for application of BLSO: 0.2Eu3+ products LFP visualization.

Dual-mode visual imaging of latent fingerprints based on organic fluorescent probe with enhanced TICT emission

Fluorescence-based imaging has emerged as a promising technique for high-resolution visualization of latent fingerprints (LFPs), but detecting LFPs by fluorescent probes remains challenging at present. Herein, a water-soluble fluorescent dye (DEPN) with red emission and twisted intramolecular charge transfer (TICT) properties was synthesized, which function as a dual-mode in-situ imaging probe for LFPs. The desired solid composite fluorescent fingerprint powder DEPN@MMT can be obtained by milling with montmorillonite (MMT) to realize the imaging of LFPs with 1–3 levels of details, which has the advantages of simple preparation, low doping ratio, good photostability, and is not limited by the substrate. Comparison with the actual fingerprint details extracted by fingerprint reader revealed a good match between the both, indicating that the fingerprint powder has high application value. The permanent preservation of LFPs with different curvatures was also realized by making rubbings. In addition, DEPN was able to image LFPs in aqueous solution with a concentration of 50 μM over a wide pH range, and it took only 20 s to obtain high-quality images that met the NFIQ2 detection standard. This dual-mode imaging probe of LFPs is highly practical, offering adaptable detection patterns for a range of complicated situations. It provides a valuable method for rapid and convenient visualization of LFPs, as well as their subsequent preservation and analysis.

AIE Active Imidazole-Stilbene Conjugated Fluorescent Probes: Illuminating Latent Fingerprints and Advancing Anticounterfeiting Technologies.

Aggregation-induced emission luminogens (AIEgens) are widely used in the realm of latent fingerprint visualization owing to their luminosity and resistance to photobleaching. However, challenges such as significant background interference and limited resolution hinder their rapid advancement. Consequently, there is a pressing need to improve the detailed visualization of latent fingerprint (LFP) imaging, particularly for analyzing level 3 details. To address this, we have designed donor-acceptor (D-A) type AIEgens named MMIMV, DMIMV, and TMIMV. These compounds exhibit robust emissions ranging from 481 to 552 nm and signify positive fluorosolvatochromism. When applied as powder dusting, these derivatives enable the fluorescence imaging of LFPs on various material substrates. The analysis of these imaged LFPs yields intricate details regarding fingerprint ridge patterns. Our results underscore the potential of highly emissive AIEgens MMIMV, DMIMV, and TMIMV as promising candidates for fingerprint visualization, thus offering significant implications for forensic investigations. Furthermore, these derivatives serve as effective fluorescent security inks for writing and drawing, presenting a novel avenue for robust anticounterfeiting applications.

Luminescent nanomaterials for developing high-contrast latent fingerprints.

Fingerprint patterns (or epidermal ridges) are by far one of the most reliable techniques for individual identification. Fingerprint patterns get deposited on all kinds of solid surfaces due to human transudation or exudation process. Bodily fluids through sweat glands contain moisture, natural oils and proteins. Since latent fingerprint patterns are not readily recognizable they are collected from a crime scene and are further processed physically or chemically. Fingerprints obtained using conventional black and white powders face severe drawbacks including low sensitivity, high background interference from the substrates, involvement of toxic materials, and poor stability. To overcome the above-listed issues, especially for coloured and transparent substrates, luminescent materials have emerged as potential agents for rapid visualization of high-contrast latent fingerprints. This review covers the recent advancements in luminescent nanomaterials of both kinds (up and down conversion) and persistent nanophosphors for developing latent fingerprints. Special emphasis has been given to an unusual class of luminescent materials known as persistent nanophosphors, which do not require a constant excitation, thereby completely eradicating background noise. The review also covers different approaches to gathering fingerprints such as powder dusting, cyanoacrylate fuming, ninhydrin fuming and vacuum metal deposition.

A smartphone-integrated bimetallic ratiometric fluorescent probe for specific visual detection of tetracycline antibiotics in food samples and latent fingerprinting

Designing and preparing highly sensitive and accurate fluorescent chemosensors for monitoring tetracycline antibiotics remains a challenge. Herein, a fluorescent chemosensor based on lanthanide metal-organic frameworks (Ln-MOFs) is proposed to realize high-precision monitoring by adjusting the ratio of lanthanide ions. Ln-MOFs with good aqueous stability were prepared by a solvothermal method using Eu3+, Tb3+ and the ligand 4,4′,4″-s-triazine-2,4,6-triyltribenzoic acid (H3TATB) in DMF/NMP/H2O. The Ln-MOFs could recognize oxytetracycline (OTC) and doxycycline (DOX), and the detection limits of OTC and DOX were as low as 8.6 and 4.8 nM, respectively. In particular, Eu(1.4 μM)-Tb-MOF sensors were used for visual detection of OTC and DOX in combination with smartphones with detection lines as low as 9.8 nM and 14.2 nM, respectively. Meanwhile, Eu-MOF, Tb-MOF and Eu(1.4 μM)-Tb-MOF can be used for latent fingerprint (LFP) visualization, demonstrating their potential applications in the field of criminal case investigation. The developed probes were successfully applied to determining OTC and DOX in milk, beef and pork with recoveries ranging from 92.0 % to 109.63 % and relative standard deviations (RSDs) ranging from 1.83 % to 4.56 %. Eu(1.4 μM)-Tb-MOF is believed to utilize its lanthanide metal ion coordination and photoinduced electron transfer (PET) mechanism to achieve highly selective and accurate OTC and DOX detection, which is supported by experimental and density functional theory (DFT) calculations.

Fluorescence and colorimetric dual-mode sensing of copper ions and fingerprint visualization by benzimidazole derivatives

In this paper, the molecular fluorescence probe H containing an imidazole structure was designed and synthesized by forming a ring between two amino groups and one aldehyde group. The synthesized probe H exhibits a Stokes shift of 144 nm with fluorescence emission at 555 nm and excitation at 411 nm. The fluorescence of probe H was quenched by the addition of Cu2+ and accompanied a red-shift of ultraviolet–visible (UV–Vis) absorption spectrum. Probe H reveals good selectivity and high sensitivity to Cu2+ in the fluorescence and UV–Vis absorption spectrum. And the limit of detection (LOD) for Cu2+ by fluorescence and UV–Vis spectrum methods were 0.14 nmol L−1 and 1.34 μmol L−1, respectively. The binding ratio of probe H and Cu2+ is 1:1 according to the Job’s plot equation. High resolution mass spectrometry (HRMS) and density function theory (DFT) calculations proved that the solvent acetonitrile and anionic chloride ion participated in the formation of H-Cu2+ complex. Furthermore, the established fluorescence analytical method was successfully applied for the detection of Cu2+ and spiked recovery experiments in tap water and mineral water. In addition, the probe exhibited outstanding solid-state fluorescence because of its excellently planar structure, and displayed a secondary fingerprint structure in the application of fingerprint detection.

Luminescence, temperature sensing and Judd-Ofelt analysis of Bi2Mo3O12:Eu3+ phosphors and the application in latent fingerprint visualization

Eu3+-activated materials have garnered significant attention due to their outstanding optical characteristics. In this work, the sol–gel method was successfully used to prepare Bi2Mo3O12 phosphors doped with different amounts of Eu3+. The generated samples were identified as orthorhombic Bi2Mo3O12 with a scheelite-like structure by X-ray diffraction analysis of the crystal structure. The sample’s morphology and size were examined using scanning electron microscopy and transmmission electron microscopy, which revealed irregular block morphology and tens to hundreds nanometers scale dimension. From the analysis of the concentration-dependent luminescence intensity of Eu3+, it was confirmed that the exchange interaction was responsible for the quenching of 5D0 fluorescence of Eu3+. When excited at 374 nm, the phosphor emitted brilliant red light, with the highest emission occurring at 616 nm (5D0→7F2 transition), and the calculated color coordinates of the sample were (0.663, 0.336). By examining the temperature dependence of the emission spectra, the temperature sensing performance of the sample and the thermal quenching behavior of Eu3+ luminescence was explored. Furthermore, the optical transition property of Eu3+ was investigated by using the emission spectra and fluorescence lifetime within the context of Judd-Ofelt theory. Ultimately, latent fingerprint visualization of the sample on various object surfaces was studied, thanks to the intense luminescence and small particle size of the Bi2Mo3O12:Eu3+ phosphor. The results indicated that the sample can clearly display the different hierarchical features of fingerprint on different object surfaces.

Latent fingerprint detection and identification using yellow-emitting YOF:Pr3+ nanophosphor

In this study, YOF:Pr3+ nanophosphors were synthesized using the microwave-assisted hydrothermal route. The structural and morphological properties of the nanophosphors calcined at different temperatures were studied in detail to optimize the synthesis conditions. The visible region and near-infrared (NIR) photoluminescence (PL) properties of the nanophosphors were obtained. Intense emission bands were observed in the blue and red regions under 250 nm excitation. The CIE chromaticity diagram showed that the color coordinates of the nanophosphors were located in the yellow region. The optimum Pr3+-concentration was found to be 0.002 mol fraction. The application of YOF: 0.002 Pr3+ nanophosphor for latent fingerprint detection was examined and evaluated on different types of surfaces. The nanophosphor demonstrated excellent adherence to the ridge patterns and sufficient sensitivity required for distinguishing between the ridges and the furrows. Different levels of detail were also observed that provided necessary information for the individualization of the fingerprints. The results suggest that the prepared YOF:Pr3+ nanophosphor can be a potential candidate for the rapid visualization and detection of latent fingerprints.

Thermal stable NaMgLaTeO6:Dy3+ double perovskite yellow phosphors for w-LEDs and latent fingerprint visualization

The novel Dy3+-doped NaMgLaTeO6 (NaMgLaTeO6:Dy3+) phosphors were produced through a high-temperature solid-state reaction. X-ray diffraction (XRD) analysis and Rietveld refinement manifest that the pure phosphor was committed to the space group (P21/m (11)) and features the double perovskite structure. The band gap (Eg) of the direct semiconductor NaMgLaTeO6 is calculated to be 2.065 eV. Under 388 nm excitation, the 4F9/2→6H13/2 energy level transition contributes to the maximum emission peak at 572 nm. Other properties of the phosphor include optimal concentration (x = 5 mol %), high thermal stability, activation energy (Ea = 0.31 eV), and internal quantum efficiency (IQE = 31.44 %). The relevant color coordinate of the white light emitting diode (w-LED) prepared by the phosphor is (0.298, 0.311). The features of the latent fingerprint (LFP) created by NaMgLaTeO6:Dy3+ can be clearly reflected on different surfaces. In summary, NaMgLaTeO6:Dy3+ phosphor has proven high potential in w-LEDs production and LFP detection.

A Comparative Analysis of Traditional Latent Fingerprint Visualization Methods and Innovative Silica Gel G Powder Approach

Latent fingerprints are a common source of information for forensic experts and law enforcement agencies. The thin layer chromatography (TLC) plates that are prepared in this work are made with silica gel G powder. Latent fingerprint remnants are made up of secretions from the nose, palm, and sebaceous, apocrine, and eccrine glands (sweat). However, the quest for more versatile and effective techniques persisted, leading to the emergence of innovative approaches like Silica Gel G powder. The silicon atoms are linked to –OH groups at the silica gel’s surface. A latent fingerprint is an imprint left by direct contact with a surface or object that is not apparent to the unaided eye. The advantages of using Silica Gel G powder for latent fingerprint visualization underscore its significance as an innovative technique in forensic science. The latent fingerprints were developed on each of the several substrates using Merck Specialties Private Limited’s white-coloured silica gel G powder. There are several techniques in the literature for creating latent fingerprints. The emergence of Silica Gel G powder in forensic science represents a significant breakthrough in the visualization of latent fingerprints. The process of using Silica Gel G powder for latent fingerprint visualization exemplifies the precision and attention to detail required in forensic investigations.