Ultraviolet Excitation Research Articles

Color tunability, concentration dependence, and temperature responsive afterglow of SrZn2(PO4)2: Eu2+, Mn2+ phosphors

Long persistent luminescence (LPL) materials with color adjustable afterglow have a wide application prospect in display and information encryption, yet there are few reports on such materials. In this paper, SrZn2(PO4)2 phosphors with tunable and thermal stimuli-responsive afterglow emissions were synthesized by a solid-state method. After ultraviolet (UV) excitation, the prepared samples exhibited emission at 419 nm, 533 nm, and 633 nm due to Eu2+: 4f65d1 → 4f7 transitions, Mn2+: 4T2(4G) →6A1(6S) transitions, and Mn2+: 4T1(4G) → 6A1(6S) transitions, respectively. The Commission Internationale de I’ Eclairage (CIE) coordinates of samples can be changed among blue, white, and yellow by varying the Mn2+ concentration. Additionally, due to the differing thermal stability of Eu2+ and Mn2+, the phosphor exhibited a temperature-responsive afterglow, and its colors can be adjusted between white and yellow over a temperature range from 293 K to 383 K. Given its distinctive temperature-responsive afterglow, the prepared phosphor is suitable for use as a temperature sensor. Moreover, the tunable afterglow colors of the phosphors are advantageous for application in anti-counterfeiting.

Few-femtosecond time-resolved study of the UV-induced dissociative dynamics of iodomethane

Ultraviolet (UV) light that penetrates our atmosphere initiates various photochemical and photobiological processes. However, the absence of extremely short UV pulses has so far hindered our ability to fully capture the mechanisms at the very early stages of such processes. This is important because the concerted motion of electrons and nuclei in the first few femtoseconds often determines molecular reactivity. Here we investigate the dissociative dynamics of iodomethane following UV photoexcitation, utilizing mass spectrometry with a 5 fs time resolution. The short duration of the UV pump pulse (4.2 fs) allows the ultrafast dynamics to be investigated in the absence of any external field, from well before any significant vibrational displacement occurs until dissociation has taken place. The experimental results combined with semi-classical trajectory calculations provide the identification of the main dissociation channels and indirectly reveal the signature of a conical intersection in the time-dependent yield of the iodine ion. Furthermore, we demonstrate that the UV-induced breakage of the C-I bond can be prevented when the molecule is ionized by the probe pulse within 5 fs after the UV excitation, showcasing an ultrafast stabilization scheme against dissociation.

Highly responsive gas sensors based on grain boundary–rich polycrystalline few-layer MoS2 films for NO2 detection

Abstract This study addresses the issues of insufficient sensitivity and poor reversibility for NO2 detection by successfully fabricating a sensor based on uniform and high-quality few-layer MoS2 polycrystalline material using chemical vapor deposition. This approach aims to improve the response of the sensor by exploiting the abundance of grain boundary (GB) defects in polycrystalline MoS2 membranes. Comprehensive surface morphology analysis of the few-layer MoS2 polycrystalline films was conducted using microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy to characterize their chemical composition and properties. Subsequently, evaluation of 1–100-ppm NO2 was conducted at room temperature (25°C). The results show excellent performance of the sensor, with a response range of 11–82.24. Notably, under ultraviolet excitation at room temperature, this sensor exhibits a response time of only 41 s to 50 ppm of NO2 with complete recovery and improved sensitivity, maintaining reliable stability over eight weeks. Furthermore, the findings reveal that the sensor demonstrates high selectivity toward NO2 gas with limit of detection and limit of qualification values of 10 and 34 ppb, respectively. Owing to the abundant adsorption sites provided by GB defects in polycrystalline thin films, the response performance of the sensor is effectively enhanced. This study provides valuable insights into the future design and development of high-performance NO2 gas sensors.

Rapid full-color serial sectioning tomography with speckle illumination and ultraviolet excitation

Three-dimensional (3D) high-resolution large-volume imaging has remained a challenge. Translational rapid ultraviolet-excited sectioning tomography (TRUST) achieves rapid and cost-effective whole-organ subcellular imaging through iterative optical scanning and mechanical sectioning. However, the axial resolution is limited by the mechanical sectioning thickness or the UV light penetration depth in tissue. Here, assisted with high-and-low-frequency (HiLo) microscopy (HiLoTRUST), the optical sectioning thickness has been reduced from tens of micrometers to ~5.8 µm. In addition, HiLoTRUST has attained a finer mechanical sectioning thickness (10–15 µm) compared to TRUST (50 µm). For high-content imaging as in TRUST, we employed two additional UV light-emitting diodes (LEDs) specifically for uniform illumination. The full-color imaging ability and improved axial resolution of HiLoTRUST have been validated by two-dimensional (2D)/3D imaging of various mouse organs and human lung cancer specimens. HiLoTRUST offers a cost-effective, full-color, and high-resolution 3D imaging approach, showing its great potential in 3D histology applications.

Exploration of Volatileomics and Optical Properties of Fusarium graminearum-Contaminated Maize: An Application Basis for Low-Cost and Non-Destructive Detection.

Fusarium graminearum (F. graminearum) in maize poses a threat to grain security. Current non-destructive detection methods face limited practical applications in grain quality detection. This study aims to understand the optical properties and volatileomics of F. graminearum-contaminated maize. Specifically, the transmission and reflection spectra (wavelength range of 200-1100 nm) were used to explore the optical properties of F. graminearum-contaminated maize. Volatile organic compounds (VOCs) of F. graminearum-contaminated maize were determined by headspace solid phase micro-extraction with gas chromatography-tandem mass spectrometry. The VOCs of normal maize were mainly alcohols and ketones, while the VOCs of severely contaminated maize became organic acids and alcohols. The ultraviolet excitation spectrum of maize showed a peak redshift as fungi grew, and the intensity decreased in the 400-600 nm band. Peak redshift and intensity changes were observed in the visible/near-infrared reflectance and transmission spectra of F. graminearum-contaminated maize. Remarkably, optical imaging platforms based on optical properties were developed to ensure high-throughput detection for single-kernel maize. The developed imaging platform could achieve more than 80% classification accuracy, whereas asymmetric polarization imaging achieved more than 93% prediction accuracy. Overall, these results can provide theoretical support for the cost-effective preparation of low-cost gas sensors and high-prediction sorting equipment for maize quality detection.

Study on luminescence properties and anti-counterfeiting application of Sr3Y2Ge3O12 doped Mn2+ long afterglow materials

Traditional anti-counterfeiting materials have the characteristics of static display of anti-counterfeiting patterns and are easy to be disturbed by background patterns. Consequently, the development of novel luminous materials represents an imperative objective. As a novel class of matrix material, Sr3Y2Ge3O12 has demonstrated considerable potential for application in the field of anti-counterfeiting. In this study, strontium yttrium germanate doped manganese ion long afterglow material was prepared by the high temperature solid phase method, and its afterglow performance and dynamic anti-counterfeiting application were studied. The experimental results show that the sample exhibits excellent luminescence characteristics. It is observed that the sample excited at 260 nm shows an emission band centred at 634 nm and a high-energy turning point at 578 nm. Using screen printing technology, design a variety of anti-counterfeiting labels. The prepared samples after ultraviolet excitation can maintain the pattern for a long time, and with the passage of time, the pattern shows dynamic attenuation, which is important in enhancing the anti-counterfeiting effect and improving product safety.

Sb3+ dopant triggered highly efficient emission in zero-dimensional organic-inorganic hybrid metal halides.

Hybrid luminescent metal halides have attracted considerable attention for their structural diversity and versatility in photonic applications. Herein, we fabricate Sb3+ doped organic-inorganic hybrid metal halides (DMA)2CsInCl6 (DMA = [CH3NH2CH3]+) single crystal. Under ultraviolet light excitation, the crystals yield bright green emission at 550 nm with near-unity photoluminescence quantum efficiency (PLQY), which is attributed to the strong electronegativity and ns2 lone pairs of Sb3+ dopants. Given the slender rod-shaped semblance, bright green emission, near-unity PLQY, and large Stokes shift, Sb3+-doped (DMA)2CsInCl6 allows the potential optical waveguide applications.

Tunable broadband luminescence of the novel Sn2+ doped oxyfluoride glass and glass-ceramics for W-LEDs

The demand for white-light luminescent materials for the white-light-emitting diodes (W-LEDs) field has been growing in modern life. In this work, a series of Sn2+ and Mn2+ ions co-doped highly transparent white-light emitting oxyfluoride glasses (precursor glass, PG) and Sr2LuF7 glass-ceramics (GC) were successfully prepared by the melt-quenching technique. Their luminescent and structural properties were investigated by the transmission spectra, excitation and emission spectra at different temperatures (300-500 K), luminescent decay curves, XRD, and TEM characterizations. Upon excitation with ultraviolet (UV) light, tunable broadband blue-white light emissions of Sn2+ were obtained by adjusting the concentration of Sn2+ ions. A conspicuous energy transfer process from Sn2+ to Mn2+ was observed in Sn2+/Mn2+ co-doped samples. Tunable broadband luminescence between blue-white light and orange-red light regions and nearly pink-white light emission was realized by varying Mn2+ concentration. Furthermore, compared to PG samples, the emissions were enhanced in GC samples due to the crystallization of Sr2LuF7 nanocrystals. Excellent thermal stability was also performed in these Sn2+ doped PG and GC samples with a recovering value of 96 % and 98.8 %, respectively. Simultaneously, Sn2+ doped PG and GC samples also own good optical thermal sensitivities with an SA value of 2.28 % and 2.47 % K-1, respectively. Our results indicate that these Sn2+/Mn2+ co-doped PG and GC may serve as tunable light sources under UV excitation and have prospects on the ratiometric optical thermometry fields.

Subpicosecond Dynamics of Rydberg Excitons Produced from Ultraviolet Excitation of Neutral Cuprite (Cu2O)n Clusters, n < 13.

The ultrafast dynamics of subnanometer neutral cuprite clusters (Cu2O)n, n < 13, are examined with pump probe spectroscopy. Upon absorption of an ultraviolet (400 nm) photon, all clusters exhibit a subpicosecond lifetime that we attribute to carrier recombination. Density functional theory (DFT) shows a change in the structural motif between small planar clusters and three-dimensional structures at n = 4. This transition is accompanied by a change in the excited state relaxation behavior, marking the onset for which lifetimes increase gradually with size. Time-dependent DFT calculations show that the excited state lifetimes align with calculated topological parameters and charge carrier delocalization associated with the formation of Rydberg excitons. Terminal Cu atoms are found to be important for the production of Rydberg excitons at the lowest optically allowed excited state. Upon excitation, the electron resides on terminal Cu atoms and the hole becomes delocalized across the remainder of the cluster.

Cyano-determined mercury (II) ion selective fluorescence assay over polymeric carbon nitride

Selective response is the key index to evaluate the performance of polymeric carbon nitride (PCN)-based heavy metal ion fluorescence sensors. Herein, to explore the role of cyano groups on selectivity, four kinds of PCN, including PCN-Cl, PCN-Ac, PCN-B and PCN-K were prepared by the molten salt method of sodium chloride and sodium acetate, the reduction method of sodium borohydride and the etching method of potassium hydroxide, respectively. These PCNs exhibited different surface cyano characteristics, but all of them had significant blue emission under ultraviolet excitation. It is proved that the assistant of sodium chloride or potassium hydroxide is an effective method to prepare PCNs with abundant surface cyano group. A series of fluorescence quenching experiments of metal ions showed that the cyano-rich degree of PCN is closely related to its selective response to mercury (II) ions. PCN-Cl and PCN-K emerged good selective quenching of mercury (II) ions, which may be related to the soft acid-soft base strong interaction between mercury (II) ions and cyano groups. Both PCN-Cl and PCN-K fluorescent probes for mercury (II) ions had a linear range of 5 ∼ 50 μmol L−1, and PCN-Cl exhibited a lower detection limit of 0.38 μmol L−1. This work confirmed the selective fluorescence response of cyano-rich PCN to mercury (II) ions, proposed the mechanism of selective fluorescence quenching response of mercury (II) ions, and provided a new idea for the design of efficient and accurate PCN-based fluorescence probes.

Colour tunability of Dy3+ & Sm3+ activated yttrium aluminium gallium nanocrystals for display applications

A set of powder samples of Y3AlGa4O12 doped with Dy3+ and Sm3+ with different concentration of Sm3+ ion were prepared via sol-gel synthesis. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive (EDS), Fourier transform infrared (FTIR) and photoluminescence spectral studies were carried out. All the diffraction peaks matched the cubic lattice Y3AlGa4O12, as given by the XRD. The SEM images revealed aggregated spherical particles ranging from 50 to 130 nm. The EDS analysis confirmed the presence of the initial chemicals in the synthesized samples. FTIR spectrum was used to examine the vibrational modes in the sample. Under a 366 nm excitation wavelength, the emission spectrum showed the peaks at 492 nm (blue), 580 nm (yellow), 673 nm (red), and 760 nm (near-infrared) corresponding to the characteristic transitions 4F9/2 → 6H15/2,13/2,11/2,9/2 of the Dy3+ ion, respectively. In comparison, the peaks at 568 nm, 614 nm, 664 nm, and 711 nm corresponded to the characteristic transitions 4G5/2 → 6H5/2,7/2,9/2,11/2 of the Sm3+ ion. Under near ultraviolet light excitation, the superposition of these blue, yellow and red colours produced excellent white light emission. The intensities of these transitions varied with the concentration of Sm3+ ion and the excitation wavelength. The emission spectrum of Dy3+ overlapped with the excitation spectrum of Sm3+, indicated possible energy transfer from Dy3+ to Sm3+. According to Inokuti-Hirayama's theory of energy transfer, the mechanism of energy transfer was understood to be quadrupole-quadrupole interaction. The CIE chromaticity co-ordinates and correlated colour temperature values showed that these samples were suitable for light-emitting diode applications.

UV wavelength-dependent photoionization quantum yields for the dark 1nπ* state of aqueous thymidine.

Despite the important role of the dark 1nπ* state in the photostability of thymidine in aqueous solution, no detailed ultraviolet (UV) wavelength-dependent investigation of the 1nπ* quantum yield (QY) in aqueous thymidine has been experimentally performed. Here, we investigate the wavelength-dependent photoemission spectra of aqueous thymidine from 266.7 to 240 nm using liquid-microjet photoelectron spectroscopy. Two observed ionization channels are assigned to resonant ionizations from 1ππ* to the cationic ground state D0 (π-1) and 1nπ* to the cationic excited state D1 (n-1). The weak 1nπ* → D1 ionization channel appears due to ultrafast 1ππ* → 1nπ* internal conversion within the pulse duration of ∼180 fs. The obtained 1nπ* quantum yields exhibit a strong wavelength dependence, ranging from 0 to 0.27 ± 0.01, suggesting a hitherto uncharacterized 1nπ* feature. The corresponding vertical ionization energies (VIEs) of D0 and D1 of aqueous thymidine are experimentally determined to be 8.47 ± 0.12 eV and 9.22 ± 0.29 eV, respectively. Our UV wavelength-dependent QYs might indicate that different structural critical points to connect the multidimensional 1ππ*/1nπ* conical intersection seam onto the multidimensional potential energy surface of the 1ππ* state might exist and determine the relaxation processes of aqueous thymidine upon UV excitation.

Large-Scale Mechanochemical Synthesis of Cesium Lanthanide Chloride for Radioluminescence.

Cesium lanthanide chloride (Cs3LnCl6), a recently developed class of lanthanide-based zero-dimensional metal halides, has garnered a significant amount of interest because of its potential applications in scintillators, light-emitting diodes, and photodetectors. Although cesium lanthanide chloride demonstrates exceptional scintillator properties, conventional synthesis methods involving solid-state and solution-phase techniques are complex and limited on the reaction scale. This study presents a facile mechanochemical synthesis method for producing Cs3CeCl6, Cs3TbCl6, and Cs3EuCl6 metal halides on a 5 g scale. These materials exhibit intense blue-violet, green, and red emissions upon ultraviolet excitation, with high photoluminescence quantum yields ranging from 54% to 93%. Furthermore, Cs3CeCl6, Cs3TbCl6, and Cs3EuCl6 metal halides exhibit intense radioluminescence spanning from the ultraviolet to the visible region. This research shows the potential of the scalable mechanochemical synthesis of lanthanide-based metal halides for the advancement of luminescent materials for scintillators.

White afterglow achieved in Eu2+, Ce3+, Dy3+co-doped LiSr4(BO3)3 phosphor

In prior study by our team, orange-yellow afterglow was observed in Eu2+ and Dy3+ co-doped LiSr4(BO3 )3 phosphor due to the emission from Eu2+ center. In this study, further incorporation of Ce3+into the phosphor lead to the observation of white afterglow due to the mixed result of blue light from Ce3+ and orange-yellow light from Eu2+ centers. Upon ultraviolet excitation, the phosphor displays a spectrum characterized from blue emission of Ce3+ at 462nm and orange-yellow emission of Eu2+ at 632nm. Fine-tuning the concentration of Ce3+ enabled the realization of white luminescence in LiSr4(BO3)3: Eu2+, Ce3+ and Dy3+phosphor with chromaticity coordinates of (0.3979, 0.2939). The photoluminescence intensities of the samples could be modulated by incorporating varying amounts of Ce3+ ions, with a critical quenching concentration identified with 0.16 Ce3+. White afterglow is also observed after the removal of the light illumination due to the existence of suitable electron traps with optimal trap depth created by the co-doped Dy3+. The underlying mechanism proposes that the white afterglow is generated by the mixed lights of blue and orange-yellow that are created by the recombination of heat-released electrons from the trap centers with pre-existing holes in the Ce and Eu emission sites.

Bright Yellow Luminescence from Mn2+-Doped Metastable Zinc Silicate Nanophosphor with Facile Preparation and Its Practical Application.

Mn2+-doped β-Zn2SiO4, a metastable phase of zinc silicate, is widely acknowledged for the uncertainties linked to its crystal structure and challenging synthesis process along with its distinctive yellowish luminescence. In this study, a vivid yellow luminescence originating from Mn2+-doped metastable zinc silicate (BZSM) nanophosphor is suggested, achieved through a straightforward single-step annealing process. The reliable production of this phosphor necessitates substantial doping, surplus SiO2, a brief annealing duration, and prompt cooling. The verification of the phase is demonstrated based on its optical and crystallographic characteristics. Moreover, the effective utilization of excimer lamps in practical scenarios is effectively demonstrated as a result of the vacuum ultraviolet excitation property of BZSM nanophosphor. This outcome paves the way for additional deployment of metastable zinc silicate in various fields, consequently generating novel prospects for future advancements.

Solid-state reaction synthesis of LuPO4:Yb3+, Tb3+ phosphors and the ultraviolet/near-infrared responsive spectra performances

Yb3+/Tb3+ co-doped LuPO4 phosphors were prepared by solid-state reaction method. The effects of Yb3+/Tb3+ doping concentrations on the downshifting and upconversion spectral performances of the synthesized phosphors were investigated. Upon the ultraviolet light excitation, the phosphors show obvious visible light emission, which can be assigned to the 5D4→7FJ (J=6, 5, 4, and 3) transitions of Tb3+ ions respectively, the green light emission at 543 nm is dominant. Upon 980 nm excitation, the phosphors display intense green and blue light emission, and weak yellow and red light emission, which originates from the cooperative energy transfer process between Yb3+ and Tb3+ ions. The synthesized LuPO4:Yb3+, Tb3+ phosphors show good ultraviolet/near-infrared responsive spectra, color-tunable and thermal-stability performances and may have potential applications in the related fields.

Multimodal anti-counterfeiting and optical storage application based on luminescence reversible modification and color change of photochromic phosphor

Reversible upconversion luminescence (RUCL) modification based on photochromism has received considerable interest due to its potential applications in optical storage and invisible optical anti-counterfeiting. Herein, white β-Ba2ScAlO5: Yb3+, Er3+ (β-BSAO-YE) phosphor was irradiated with 254 nm light, which caused the phosphor to turn blue due to the increase of oxygen vacancy. The blue β-BSAO-YE phosphor returns to its original color upon stimulation with 808 nm laser light or 125 °C, exhibiting a double photo-induced reversible photochromic change. The green and red upconversion luminescence (UCL) of the β-BSAO-YE were reversibly modified according to their photochromic properties. The UCL modification changes the luminescence color of the pattern, indicating that β-BSAO-YE phosphor is an ideal compound anti-counterfeit agent. The light information recorded on the β-BSAO-YE binary photochromic dot matrix can be read under ultraviolet (UV) and near-infrared (NIR) excitation, demonstrating the potential application of β-BSAO-YE phosphors as optical data storage media. In addition, the cyclic experiment showed good photochromic and UCL modulation repeatability. The new luminescent β-BSAO-YE not only proposes a new way to exploring upconversion red light materials, but also provides new materials for optical storage, optical information and optical anti-counterfeiting.

A Theoretical Exploration of the Photoinduced Breaking Mechanism of the Glycosidic Bond in Thymine Nucleotide.

DNA glycosidic bond cleavage may induce cancer under the ultraviolet (UV) effect. Yet, the mechanism of glycosidic bond cleavage remains unclear and requires more detailed clarification. Herein, quantum chemical studies on its photoinduced mechanism are performed using a 5'-thymidine monophosphate (5'-dTMPH) model. In this study, four possible paths were examined to study the glycosidic bond cleavage. The results showed that, upon excitation, the electronic transition from the π bonding to π antibonding orbitals of the thymine ring leads to the damage of the thymine ring. Afterwards, the glycosidic bond is cleaved. At first, the doublet ground state (GS) path of glycosidic bond cleavage widely studied by other groups is caused by free electron generated by photoirradiation, with a kinetically feasible energy barrier of ~23 kcal/mol. Additionally, then, the other three paths were proposed that also might cause the glycosidic bond cleavage. The first one is the doublet excited state (ES) path, triggered by free electron along with UV excitation, which can result in a very-high-energy barrier ~49 kcal/mol that is kinetically unfavorable. The second one is the singlet ES path, induced by direct UV excitation, which assumes DNA is directly excited by UV light, which features a very low-energy barrier ~16 kcal/mol that is favored in kinetics. The third one is the triplet ES path, from the singlet state via intersystem crossing (ISC), which refers to a feasible ~27 kcal/mol energy barrier. This study emphasizes the pivotal role of the DNA glycosidic bond cleavage by our proposed direct UV excitation (especially singlet ES path) in addition to the authorized indirect free-electron-induced path, which should provide essential insights to future mechanistic comprehension and novel anti-cancer drug design.

Excitation-dependent luminescent and optical thermometric properties of Er3+ and Yb3+ Co-doped K5Y(P2O7)2

We investigated the luminescent and optical thermometric properties of Er3+ and Yb3+ co-doped K5Y(P2O7)2 (KYP) with dependence on the excitation wavelength. To examine the role of Yb3+ ions in excitation-dependent luminescence, we synthesized three series of samples: an Er3+ singly doped KYP sample, and two Er3+ and Yb3+ co-doped KYP samples with varying concentrations of Er3+ or Yb3+. Although our samples exhibited visible and near-infrared (∼1550 nm) emissions under ultraviolet excitation, the doping with Yb3+ disturbed the luminescence of Er3+. In the case of 980 nm excitation, we identified upconversion luminescence (UCL) and 1550 nm luminescence; they were enhanced significantly via doping with Yb3+, which served as a sensitizer via energy transfer to Er3+. Our samples demonstrated excellent optical thermometric properties under 980 nm excitation compared with under ultraviolet excitation. In particular, the relative sensitivity of the UCL spectra was 1.01 %/K at 293 K. These results suggest the promising potential of using our Er3+ and Yb3+ co-doped KYP as an optical thermometer under 980 nm excitation.

Cooling Condition Effect on Spectral Properties and Smartphone-Based Anticounterfeiting Application of Zn3Ga2Ge2O10/Cr3+ Phosphors.

The influence of cooling history for the Zn3Ga2Ge2O10/Cr3+ phosphors prepared by solid state reaction on the spectral properties was discovered, and an anticounterfeiting scheme based on the identification with smartphone was proposed and experimentally demonstrated using the studied phosphors. A combination of color-tunable visible fluorescence emission and near-infrared (NIR) afterglow emission in Zn3Ga2Ge2O10/x mol % Cr3+(x = 0, 0.05, 1, 2, 3, and 4) phosphors to achieve multimode anticounterfeiting was reported. It is found that with the increasing Cr3+ concentrations, the visible emission can be tuned from green, light pink, and light red to deep red under 254 nm ultraviolet (UV) excitation. This phenomenon is related to the formation of oxygen vacancies in the host during the process of natural cooling and the characteristic emission of Cr3+. In addition, the persistent time of the Cr3+ emission centered at 700 nm can be also tuned by various Cr3+ concentrations. A possible mechanism was deduced to explain the afterglow phenomenon. Lastly, a flower pattern applied in anticounterfeiting was fabricated using the Zn3Ga2Ge2O10/x mol % Cr3+ (x = 0, 0.05, 1, 2, 3, and 4) phosphors to present tunable color and NIR afterglow signals at different excitation modes, and the camera of smartphone was chosen as a detection tool to take the NIR images. The results obtained above suggest that the prepared phosphors at natural cooling condition have great potential in affording advanced optical anticounterfeiting.