Ion Beam Induced Luminescence Research Articles

In situ luminescence measurements of GaN/Al2O3 film under different energy proton irradiations

Ion beam-induced luminescence (IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al2O3 at varying ion energies, which allowed for the measurement of defects at different depths within the material. The energies of H+ were set to 500 keV, 640 keV and 2 MeV, the Bragg peaks of which correspond to the GaN film, GaN/Al2O3 heterojunction and Al2O3 substrate, respectively. A photoluminescence measurement at 250 K was also performed for comparison, during which only near band edge (NBE) and yellow band luminescence in the GaN film were observed. The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed, and both exhibited a decrease with the fluence of H+. Additionally, the luminescence of F centers, induced by oxygen vacancies, and Cr3+, resulting from the 2E →4A2 radiative transition in Al2O3, were measured using 2 MeV H+. The luminescence intensity of F centers increases gradually with the fluence of H+. The luminescence evolution of Cr3+ is consistent with a yellow band center, attributed to its weak intensity, and it is situated within the emission band of the yellow band in the GaN film. Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy. Luminescence measurement can be excited by various techniques, but IBIL can satisfy in situ luminescence measurement, and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions. The evolution of defects at different layers with ion fluence can be obtained.

Ion beam induced luminescence analysis of europium complexes in styrene-divinylbenzene copolymer-coated spherical silica by proton and argon ion beams irradiation

Ion beam induced luminescence (IBIL) analysis of adsorbents containing Eu complexes was carried out using a 3-MV single-ended accelerator and an azimuthally varying field cyclotron to evaluate structures of complexes in an extraction chromatography. Some adsorbents were prepared by impregnating a styrene-divinylbenzene copolymer-coated porous silica particle (SiO2-P) with extractants. The IBIL spectra of Eu complexes in the adsorbents produced some differences depending on the kinds of extractants. The experimental results imply that the difference in the IBIL spectra of Eu complexes in the adsorbents is caused by the difference in the structures. The only clear luminescence peak in the alkyl diamide amine (ADAAM) with n-octyl and 2-ethylhexyl alkyl chains (ADAAM(Oct, N(EH))) adsorbent was not observed by H+ ion beam irradiation. Meanwhile, the luminescence of Eu could be detected by irradiation of an Ar8+ ion beam. The luminescence of Eu complexes is presumed to be easily detected by high linear energy transfer (LET) beam irradiation. The symmetric properties of Eu complexes were evaluated with the luminescence due to the 5D0 → 7F2 transition, and it is implied that ADAAM with 2-ethylhexyl alkyl chains (ADAAM(EH, N(EH))) is a high asymmetry property. The luminescence intensity of Eu complexes in the adsorbent decreased with the ion beam irradiation because extractants were damaged by the ion beam. This phenomenon was clearly observed by irradiation of high LET ion beam, Ar8+.

Ion fluence-dependent luminescence of the Yb2+ centre in an undoped YAG single crystal

In this work, the ion beam-induced luminescence of Yb2+ with the 4f136s ground state in an undoped YAG single crystal was studied. The 4f135d(2F7/2eg) → 4f136s transition of Yb2+ in the form of Re-F centres exhibits seven iconic narrow emission bands in the 590–720 nm range. The comparison of experimental data suggests that the IBIL spectrum is superior tothe RL spectrum in characterizing the trace rare earth element Yb2+. A decrease in the Yb2+ luminescence intensity was observed under increasing ion fluence, which can be effectively described by a single exponential model. The probable explanations for the luminescence decay behaviour of Yb2+ with increasing fluence were discussed based on SRIM simulation data and the evolution of the peak parameters with fluence, which was a powerful supplement to previous research. Even when the ion fluence reaches 1014 cm−2, the luminescence intensities of the seven Yb2+ luminescence peaks in the YAG single crystal are still more than 60% of the initial luminescence intensity, showing that the Yb2+:4f135d(2F7/2eg) → 4f136s transition has good radiation resistance.

Virtual photon approach of cathodoluminescence and ion-beam induced luminescence of solids

A novel analysis of cathodoluminescence (CL) and ion-beam induced luminescence (IBIL) is presented on the basis of virtual photon spectra (VPS) produced by charged particles (electrons or ions) passing by luminescent species such as defects or impurities, in wide band-gap ionic-covalent solids. A discussion is provided for irradiations in a wide range of charged particle kinetic energy by using the Weizsäcker-Williams theory. The computed VPS are found to decay rapidly as a function of virtual photon (VP) energy regardless of particle energy, for close or distant collisions. The electron-energy dependence of experimental CL spectra of sapphire (α-Al2O3) is discussed in relation to the computed VPS for the primary and secondary electrons. The experimental IBIL spectra of α-Al2O3 are also analyzed in this framework for protons and helium ions in the MeV energy range. The variations of stopping power are consistent with the variation of the number of emitted VPs. The decay of IBIL yield versus ion stopping power is discussed on the basis of the variation of the computed VPS, and ionization and excitation induced by primary ions and secondary electrons. This decay is accounted for by a decrease of the yield of low-energy secondary electrons with the subsequent VP emission.

IBIL Measurement and Optical Simulation of the DI Center in 4H-SiC

In this paper, DI defects are studied via experiments and calculations. The 2 MeV H+ is used to carry on an ion-beam-induced luminescence (IBIL) experiment to measure the in-situ luminescence of untreated and annealed 4H-SiC at 100 K. The results show that the luminescence intensity decreases rapidly with increasing H+ fluence, which means the losses of optical defect centers. In addition, the evident peak at 597 nm (2.07 eV) is the characteristic peak of 4H-SiC, and the weak peak between 400 nm and 450 nm is attributed to the DI optical center. Moreover, the first-principles calculation of 4H-SiC is adopted to discuss the origin of DI defects. The optical transition of the defect SiC(CSi)2 from q = 0 to q = 1 is considered the experimental value of the DI defect center.

Probing the Cr3+ luminescence sensitization in β-Ga2O3 with ion-beam-induced luminescence and thermoluminescence

Ion-beam-induced luminescence (IBIL) measurements were performed in Cr-doped β-Ga2O3 using both protons and helium ions, showing a strong enhancement of the Cr3+ luminescence upon ion irradiation. Theoretical modelling of the IBIL intensity curves as a function of the fluence allowed estimating the effective cross-sections associated with the defect-induced IBIL enhancement and quenching processes. The results suggest that sensitizing the Cr3+ luminescence is more efficient for H+ than for He+ irradiation. Thermoluminescence (TL) studies were performed in the pristine sample, with no TL signal being observed in the spectral region corresponding to the Cr3+ emission. In agreement with the IBIL study, upon ion irradiation (with either protons or helium ions), this TL emission is activated. Moreover, it can be quenched by annealing at 923 K for 10 s, thus revealing the role played by the defects induced by the irradiation. These results show that the irradiation-induced defects play a major role in the activation of the Cr3+ luminescence, a fact that can be exploited for radiation sensing and dosimetry.

Temperature and fluence dependence of the luminescence properties of Ce:YAG single crystals with ion beam-induced luminescence

The emissions of Ce3+ in Ce:YAG are at approximately 550 nm and are generated by the overlapping emission of two transitions 5d →2F5/2 (2F7/2), and their luminescence characteristics are markedly influenced by temperature and ion fluence. In this study, the temperature and ion fluence dependence of Ce3+ emission was investigated using ion beam-induced luminescence (IBIL) at four different temperatures (25, 150, 300, and 450 °C), and potential theoretical explanations for the variation were discussed. Experimental results show that (1) as the temperature increases, the intensity of Ce3+ decreases, and the central peak position continues to redshift; (2) as the temperature rises, the proportion of the high-energy peak at approximately 2.3 eV continuously increases; (3) a double exponential model can describe the evolution of the Ce3+ luminescence intensity with fluence; and (4) the influence of 2 MeV H+ on the luminescence characteristics of Ce:YAG is limited. The luminescence characteristics of the Ce:YAG single crystal deteriorate when exposed to high temperatures. Combined with the observed experimental phenomena, we recommend that the practical operating temperature of the Ce:YAG single crystal in a high ion fluence environment should be as low as 150 °C when possible to ensure a high scintillation yield and good luminescence performance.

Effect of point defects on the STE luminescence of CaF2 single crystals

The study is devoted to the radiation defects created in the calcium fluoride single crystals with reactor irradiation to the fluence of 3.7 × 1017 thermal and 4.6 × 1017 fast (En > 1 MeV) neutrons per cm2, and their effect on the luminescence of the crystals. UV–VIS absorption spectroscopy revealed the formation of point defects, mainly F and F2 centers. From the comparison of the annealing behavior of the absorption and the ion-beam-induced luminescence (IBIL), we conclude that the color centers are responsible for a non-radiation decay of self-trapped excitons (STEs) and thus cause the luminescence quenching. In addition, the Raman analysis revealed a disorder of about 44% and a stress formation in the material after the neutron irradiation. Annealing at 100 °C reduces the disorder to 13% and eliminates the stress.

Ion beam induced luminescence (IBIL) analysis of europium-activated phosphate glass micro-beads scintillators at clinical carbon beam therapy field

The possibility of real-time monitoring of clinical carbon beams was investigated by analyzing ion beam induced luminescence (IBIL) using phosphate glass (PG) with a dopant of europium (Eu). Phosphate glass with a silver activator (PG: Ag) is known as a substrate for personal dosimeters. Several trials are being made by utilizing PG: Ag as an in-situ diagnostic tool for the clinical radiation therapy field. However, silvers are not actively responding to the radiation during the irradiation because of their build-up effect. In this study, we introduced a co-activator of europium, which is expected to coexist with silvers and have a scintillator property for real-time response. IBIL was successfully visualized with each bunch of 290 MeV/n from synchrotron under different beam intensity from 6.0×106 to 3.0×109 (clinical beam condition) counts/spill. IBIL measurement at each position of Bragg peak suggested that developed PG:Ag-beads with Eu co-activators have successfully demonstrated real-time radiation monitoring of clinical carbon beams.

The newly installed IBIL (Ion Beam Induced Luminescence) set-up at CEDAD-University of Salento: design and first applications on perovskite

We present the design and implementation of the new Ion Beam Induced Luminescence set-up recently installed and tested at the Centre of Applied Physics, Dating and Diagnostics of the University of Salento. The set-up allows the irradiation of samples at atmospheric pressure with MeV protons produced by a 3 MV Tandetron accelerator and extracted in air through a kapton membrane. Ion beam induced luminescence is collected by an optical fiber and analyzed by an imaging spectrometer. Simultaneously, characteristic X-Rays emitted by the sample are detected by a Silicon Drift Detector (SSD) detector. The system also allows combined photoluminescence measurements by using an excitation laser focused onto the samples. First applications in the analysis of all-inorganic perovskites (CsPbBr3) deposited by PLD (Pulsed Laser Deposition) are presented.

Facile synthesis of ZnO/CWO nanocomposite with brilliant enhanced optical response

In this research, novel zinc oxide/cadmium tungstate (ZnO/CWO) nanocomposite was prepared by a simple chemical method. The prepared nanocomposite was characterized for its structural and optical properties by different techniques. For the first time, the radiation response of prepared nanocomposite was studied using 241Am alpha source and ion beam induced luminescence (IBIL) measurement. Also, photocurrent transient responses of the prepared nanocomposite were recorded under Xe source radiation. ZnO/CWO nanocomposite exhibited strong light emission in the blue-green range at room temperature. Under alpha irradiation, the ZnO/CWO nanocomposite showed an excellent sensitivity when compared to pure ZnO or CWO. FESEM and TEM images showed a uniform distribution of spherical nanoparticles with an average particle size of 77 nm. XRD, XPS, and EDX results indicated characteristic peaks of ZnO, CWO, and related elements in the composite. Fourier transform infrared spectroscopy confirmed the presence of several groups in the nanocomposite. Investigations indicated that the optical quality of the ZnO/CWO nanocomposite was improved when compared with pure ZnO and CWO. According to obtained results, it is anticipated that ZnO/CWO nanocomposite would hold suitable potential for applications in optoelectronic devices and detection.

Temperature dependence of ZnO crystals from ion-beam-induced luminescence

The effect of temperature (300-100 K) on the luminescence behavior of ZnO crystals irradiated with 2 MeV H+ were reported by ion-beam-induced luminescence (IBIL). Compared with constant-temperature IBIL spectra, the fluence mainly affects the luminous intensity, and the peak position shift is mainly affected by the temperature. For deep-band emissions (DBEs) at temperature ranges of 300–200 K, three emission bands exist in the red, orange-red, and green regions. These three emission bands illustrate different temperature dependencies with decreasing temperature: red and orange-red emission bands are not sensitive to temperature and redshift to green emission bands. The origins of three emission bands are the radiative recombination of deeply trapped holes with shallowly trapped electrons at the Oi, transition from the Zni to Oi level and transition related to oxygen vacancy levels. For DBE of 200–100 K, the orange-red emission band is not sensitive to temperature and has the same origin as the high-temperature section. The temperature dependence of UV band emission associated with recombination of excitons is caused by the temperature-induced band-gap shrinkage. The abnormal movement with temperature of violet emission band associated with Zni results from competition between localization effect at Zni and the band-gap shrinkage.

Optical spectral study of Nd3+ in YSZs with ion beam-induced luminescence

Ion beam-induced luminescence (IBIL) spectroscopy based on the stark level characteristics of trivalent neodymium (Nd3+): 4F3/2 → 4I9/2 emissions is a powerful tool for characterizing material molecules and crystal structures and quantifying radiation damage. Its spectral parameters are considered to characterize the molecular and crystal structure environment and to track the degree of short-range order disturbance of cationic sites. However, IBIL-based related technologies have rarely been reported. In this article, the IBIL of Nd3+ in yttria-stabilized zirconia (YSZs) was studied in the near-infrared region, especially the Nd3+: 4F3/2 → 4I9/2 emission at room temperature with 2 MeV H+. The results show that 1) a single IBIL spectrum carries as much information about the structure of a substance as the PL spectrum. 2) The surrounding crystal environments of Nd3+ cations in the three samples are consistent. 3) H+ does little damage to the sample in the course of analysis.

The origin of the 500 nm luminescence band related to oxygen vacancies in ZrO2

In this paper, ion-beam-induced luminescence (IBIL) spectra of raw ZrO2 irradiated with 2 MeV H+ ions and photoluminescence (PL) spectra of annealed (200, 500 and 800 °C in air, nitrogen or oxygen) ZrO2 were investigated. The luminescence intensity decreased with increasing fluence, which indicated that the concentration of luminescence centers decreased during irradiation. The PL spectral results show that, with increasing partial pressure of oxygen during annealing, the intensity of luminescence decreases due to the decrease in oxygen vacancies. First-principles calculations were used to study the formation energy and transition level for oxygen vacancies (Vo), Ti-substituted Zr (Ti) and Ti adjacent to the nearest Vo (Ti-Vo) complex. The binding energies of Ti3+ and Vo + are 2.10 eV, which indicates that oxygen vacancies benefit the formation of Ti3+. The calculated configuration coordinate diagram and IBIL results indicated that Vo is not the luminescence origin. A new light-emitting structure of the Ti-Vo complex (FA center) structure was proposed based on our calculations and previous studies. The calculated results of the luminescence model match the PL and IBIL spectra remarkably. The emission band of ZrO2 at approximately 500 nm was assigned to the FA center or Ti3+ (the eg to t2g transition) adjacent to Vo+.

Effect of different type of dopants on the enhancement of KCl single crystal optical properties

As the most attractive phosphors, the enhancement of the optical properties of single crystalline alkali halides such as KCl using different types of dopants was approached. Pure and doped KCl single crystals were grown using Czochralski method. Different activators such as Ag, In, Mn, and Sn ions were employed to enhance the optical properties of grown KCl single crystals. The structure of the single crystalline samples was investigated through X-ray diffraction (XRD). The optical properties of the samples were studied by employing UV–vis spectroscopy, photoluminescence (PL) analysis and ion beam-induced luminescence (IBIL), to confirm the incorporation of dopants into the host lattice. In the PL spectra of the samples, two UV and near UV emission lines and one red emission line were detected in the PL spectrum of the pure sample at 357 nm, 420 nm and 697 nm respectively that have not been reported before. Dopants led to the change in the intensity and position of the peaks. The peaks at 420 nm and 697 nm in the doped samples were shifted towards shorter wavelengths and a 500 nm emission was emerged due to impurities. The IBIL analysis proposed the violet color center for the Sn and Mn doped samples. These peaks turn the KCl single crystals into attractive phosphors.

Surface structure investigation by means of ion beam-induced luminescence imaging: A preliminary study

The idea of ionoluminescence 3-D imaging is introduced to provide surface structural information of luminescent samples from a depth of tens of micrometers. Application of broad ion beam in an in-air setup results in capturing high resolution 2-D images in short times. Therefore, ionoluminescence 3-D imaging is a non-destructive technique which can extract information such as inhomogeneity, porosity and roughness, especially from historical precious samples. In order to display the capabilities of the ionoluminescence 3-D imaging technique, the 3-D image of an inhomogeneous lapis lazuli sample is produced based on stereo-ionoluminescence approach. The results are indicative of high potentials of the applied imaging technique for revealing surface structural information of luminescent samples.

Synthesis condition effects on the emission enhancement of YBO3 powder

In the present study, self-activated YBO3 powder was successfully synthesized via a facile solid-phase method using ammonium tetraborate tetrahydrate. A modified synthesis temperature (900 °C) reduced the nanoparticle sizes up to 5 nm. Very detailed investigations using different characterization methods such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman and photoluminescence (PL) spectroscopies, and ion beam-induced luminescence (IBIL) were performed. Raman spectrum confirmed the presence of small amounts of boron in BO3 coordination. PL spectroscopy of the synthesized YBO3 powder showed that the prepared sample emitted a strong blue emission band centered at 416 and an intense green emission band centered at 480 nm. Another green emission line at 529 nm with lower intensity was also detected at all excitations. IBIL spectrum showed a broad UV-blue emission line from 220 to 450 nm and two green emission lines. These emission lines were observed without any dopant. They were the result of the size of particles and boron in BO3 coordination which leads to vacancy defects. The results of the study demonstrated that the ultrafine microstructures and the existence of boron in the three-fold coordination played critical roles in receiving new optical properties.

In situ luminescence measurement of 6H-SiC at low temperature**Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 11905010), the Fundamental Research Funds for the Central Universities, China (Grant No. 2018NTST04), the China Postdoctoral Science Foundation (Grant No. 2019M650526), and Guangdong Province Key Area R&D Program, China (Grant No. 2019B090909002).

To understand the evolution of defects in SiC during irradiation and the influence of temperature, in situ luminescence measurements of 6H-SiC crystal samples were carried out by ion beam induced luminescence (IBIL) measurement under 2 MeV H+ at 100 K, 150 K, 200 K, 250 K, and 300 K. A wide band (400–1000 nm) was found in the spectra at all temperatures, and the intensity of the IBIL spectra was highest at 150 K among the five temperatures. A small peak from 400 nm to 500 nm was only observed at 100 K, related with the D1 defect as a donor–acceptor pair (D–A) recombination. For further understanding the luminescent centers and their evolution, the orange band (1.79 eV) and the green band (2.14 eV) in the energy spectrum were analyzed by Gaussian decomposition, maybe due to the donor–deep defect/conduction band–deep defect transitions and Ti related bound excition, respectively. Finally, a single exponential fit showed that when the temperature exceeded 150 K, the two luminescence centers’ resistance to radiation was reduced.

Ions beam induced luminescence study of variation of defects in zinc oxide during ion implant and after annealing

<sec>The optical and electrical properties of ZnO related on the type and the concentration of defects in ZnO crystal. Ion implantation and annealing can change the type and the concentration of defects in ZnO. To understand the variation of defects in ZnO during ion implantation and after different temperature annealing, in situ luminescence measurements of ZnO crystal samples were carried out by ion beam induced luminescence (IBIL) during ion implantation of 2 MeV H<sup>+</sup> and then after annealing at 473 K and 800 K in vacuum on the GIC4117 tandem accelerator in Beijing Normal University.</sec><sec>IBIL spectra of ZnO showtwo emission peaks: UV emission, which is called near band emission (NBE), and visible emission, which is called deep band emission (DBE).The high-intensity of DBE and weak NBE of IBIL spectra of ZnOmay be due to the NBE is intrinsic to ZnO samples and therefore is just visibly observed from samples that are virtually defect-free. With the ion implantation, the destruction of the crystal structure and the arising of a mass of defects, inducing the weak intensity NBE and intense DBE.In addition, the overall IBIL spectra of ZnOreveal decrease intensity with the ion fluence,which indicates that the concentration of luminescence centersdecreases duringion implantation.With the H<sup>+</sup> fluence, the concentration of the point defects increases. The point defects migrate and subsequently agglomerate into larger defect clusters. These defect clusters serve as traps for catching electrons and holes, which result in the quenching of luminescence centres. Annealing can help todecompose the defect clusters and repair the defects of crystal. However, amounts of defects and clusters still remain in the irradiated sample annealed at 473 K in vacuum, which acted as nonradiative center and suppress the luminescence induced weak intensity of IBIL. Annealing the sample at 800 K in vacuum may facilitate the decomposition of defect clusters during ion irradiation to point defects and the point defect return to the lattice position that can reduce the nonequilibrium defects inside the crystal and improve the crystallinity of the crystal, which increase the intensity of its IBIL.</sec>

Micro-ion beam-induced luminescence spectroscopy for evaluating SiAlON scintillators

Ion beam-induced luminescence (IBIL) spectroscopy was used for luminescent material characterization and analysis for the investigation of new scintillator families. Under continuous 3 MeV proton microbeam irradiation, the crystal structures of α-SiAlON:Eu, β-SiAlON:Eu, and CaAlSiN3 (CASN) emitted bright luminescence at peak wavelengths of 605, 540, and 670 nm, respectively. As the irradiation progressed, the IBIL intensity of the conventional ZnS:Ag scintillator decreased sharply, whereas that of the SiAlONs and CASN remained within the detection limit. IBIL spectroscopy was performed on individual grains of the SiAlON scintillators. IBIL imaging and spectroscopy of two grains of β-SiAlON:Eu showed that the main peak in the IBIL spectrum of β-SiAlON:Eu obtained from a large-area beam scan consisted of several small peaks, which were observed in spectra from individual grains. Our experimental results suggest that microscopic spectroscopy of IBIL is an effective tool for microscopic material characterization of luminescent targets.