Luminescence Methods Research Articles

Crystal-chemical characterisation and spectroscopy of fluorcarletonite and carletonite

AbstractThe minerals of carletonite group, fluorcarletonite, KNa4Ca4[Si8O18](CO3)4(F,OH)·H2O and carletonite, Na4Ca4[Si8O18](CO3)4(OH,F)·H2O, were investigated using a multi-method approach. A detailed comparative chemical study of the minerals was carried out using electron probe microanalysis and Fourier transform infrared spectroscopy. Using X-ray techniques and the results obtained, geometrical and distortion characteristics of the mineral structures are calculated and the successful crystal-structure refinement of these two natural compounds are given. Using spectroscopic and luminescence methods and ab initio calculations, it is shown that hole defects (CO3)•– are responsible for the colouration of the samples studied. Luminescence due to 5d–4f transition in Ce3+ ions is observed in both investigated compounds. Moreover, luminescence attributed to intrinsic luminescence, corresponding to the decay of electronic excitations of (CO3)2– complexes in the carletonite sample, is registered for the first time in phyllosilicates. An analysis of the optical absorption spectra and g-tensor values suggests that (CO3)•– defects in the crystal structure are localised in the C1 positions. Identification of these specific properties for these sheet silicates, with a two-dimensional infinite tetrahedral polymerisation, indicates that carletonites could be prospective materials for novel phosphors and luminophores.

Synergistic anticancer effects of crocin combined with deuterium-depleted water on HT-29 cells.

Colorectal cancer is one of the most common types of cancer in the world and the study of the role of nutrients in preventing or inhibiting the growth of this cancer is of interest to scientists. In this article, the synergistic effect of deuterium-depleted water(DDW) and crocin at specific concentrations on HT-29 cells was investigated. In this regard, HT-29 cells were grown in RPMI medium containing DDW, alone and in combination with crocin for 24, 48 and 72 h. Cell viability, cell cycle changes and antioxidant enzymes status were determined by MTT assay, flow cytometry and quantitative luminescence methods, respectively. The results of these analyses proved the cell growth inhibitory effect of deuterium alone and its synergistic effect in combination with crocin. The cell cycle analysis showed an increase in the number of cells in the G0 and G1 phases whereas there was a decrease in the number of cells in the S, G2 and M phases. The activities of superoxide dismutase and catalase enzymes also decreased compared to the control group that is a reason to increase Malonyl dialdehyde factor. The results suggested that a combination of DDW and crocin can open a new strategic approach in the prevention and treatment of colorectal cancer.

The Effect of Instability of KCl:Na Single Crystals

For the first time, the stability of KCl single crystals doped with sodium impurity ions was analyzed via the optical absorption and luminescence methods. Using the characteristic bands of optical absorption, as well as of X-ray and tunnel luminescence, ascribed to radiation defects and exciton-like formations localized near sodium impurity, the removal of Na+ ions from regular cation sites into nanosized clusters in KCl:Na crystals stored for a long time at room temperature was demonstrated. At the same time, the subsequent annealing of such “decayed” crystals at high temperature (400–700 °C) led to a partial incorporation of sodium impurity ions back into cation sites and the restoration of a homogeneous distribution of Na+ in the KCl:Na lattice. With an increase in the quenching temperature, the restoration degree continuously increased until it reached the saturation level (about 80% of the characteristics of a freshly grown crystal). The detectable/disappearing X-ray-induced absorption bands at 6.3 and 3.5 eV (respectively ascribed to interstitial chlorine ions and atoms localized near Na+), as well as the luminescence bands at 2.8 and 3.1 eV, typical of recombinationally generated exciton-like formations near Na+ or Na+-Na+, were the indicators of sodium ion redistribution in the crystal lattice.

State of the Art on Developments of (Bio)Sensors and Analytical Methods for Rifamycin Antibiotics Determination.

This review summarizes the literature data reported from 2000 up to the present on the development of various electrochemical (voltammetric, amperometric, potentiometric and photoelectrochemical), optical (UV-Vis and IR) and luminescence (chemiluminescence and fluorescence) methods and the corresponding sensors for rifamycin antibiotics analysis. The discussion is focused mainly on the foremost compound of this class of macrocyclic drugs, namely rifampicin (RIF), which is a first-line antituberculosis agent derived from rifampicin SV (RSV). RIF and RSV also have excellent therapeutic action in the treatment of other bacterial infectious diseases. Due to the side-effects (e.g., prevalence of drug-resistant bacteria, hepatotoxicity) of long-term RIF intake, drug monitoring in patients is of real importance in establishing the optimum RIF dose, and therefore, reliable, rapid and simple methods of analysis are required. Based on the studies published on this topic in the last two decades, the sensing principles, some examples of sensors preparation procedures, as well as the performance characteristics (linear range, limits of detection and quantification) of analytical methods for RIF determination, are compared and correlated, critically emphasizing their benefits and limitations. Examples of spectrometric and electrochemical investigations of RIF interaction with biologically important molecules are also presented.

Diagnosis of the technology of titanium and hafnium oxides by luminescence methods

The article shows the role of oxygen vacancies in the formation of luminescence bands of titanium and hafnium oxides, and also demonstrates the relationship between the intensity of luminescence bands and the conditions for the synthesis of films of these materials. It is concluded that photoluminescence is a very sensitive method for diagnosing the composition of oxides. Luminescence bands at 2.45 eV in titanium oxide and 2.91 eV in hafnium oxide make it possible to analyze the change in the film composition under various technological conditions of their production. Keywords: oxygen vacancies, titanium oxide, hafnium oxide, photoluminescence.

Diamonds of the Ebelakh placer (Anabar, Yakutia): new data on the division by primary sources

Based on the data obtained during the study of a representative collection of diamonds of the Ebelah placer by morphological analysis, luminescence, IR and EPR methods, a scheme for dividing crystals into three groups, presumably related to the primary sources of diamonds, is proposed. The separation is based on the statistical distribution of diamonds in the collection according to the content of A (IR) centers; the validity of the allocation of three groups is confirmed by the revealed differences in crystals of these groups in a significant part of typomorphic features, including habitus, surface morphology, color, visual luminescence, the presence of twins and accretions, the degree of mechanical wear, etc.

PROCYONIDAE (CARNIVORA) IN A CAVE IN THE PARQUE NACIONAL DE UBAJARA, NORTHEAST OF BRAZIL (EOHOLOCENE)

The most recent procyonids of Brazil came from North America at the end of the Pleistocene. This work presents and describes the first carnivore record (Procyonidae Gray, 1825) found in a cave deposit and collected from dated sediments in northeastern Brazil. The collection was made during an excavation mission at the Gruta do Urso Fóssil, Parque Nacional de Ubajara, State of Ceará. The studied material was found at a depth of 0.8 m. Using the Thermoluminescence and Optically Stimulated Luminescence methods, the material was dated to ± 8,450 years BP. The animal is represented by a maxilla fragment with a complete right M2 and can be attributed to Procyon cancrivorus (Cuvier, 1798). The presence of this species in this area suggests that the environmental dynamics of the region has been harmonious and conserved for, at least, the last 8,000 years.

Editorial: Luminescence and electrochemical methods: Analysis of physical evidence

EDITORIAL article Front. Anal. Sci., 22 November 2022Sec. Forensic Chemistry Volume 2 - 2022 | https://doi.org/10.3389/frans.2022.1080042

AIEgen-Enabled Multicolor Visualization for the Formation of Supramolecular Polymer Networks.

Extensive reports on the use of supramolecular polymer networks (SPNs) in self-healing materials, controlled release system and degradable products have led more researchers to tap their potential owing to the unique properties. Yet, the attendant efforts in the visualization through conventional luminescence methods during the formation of SPNs have been met with limited success. Herein, we designed a special type of SPNs prepared by PPMU polymer chains containing pyrene benzohydrazonate (PBHZ) molecules as AIEgens for the multicolor visualization with naked eyes. The complete detection of the formation process of the networks relied on the PBHZ molecules with aggregation-induced ratiometric emission (AIRE) effect, which enabled the fluorescence of the polymer networks transits from blue to cyan, and then to green with the increasing crosslinking degree derived from the hydrogen bonds between 2-ureido-4-pyrimidone (UPy) units of the polymer chains. Additionally, we certificated the stimuli-responsiveness of the obtained SPNs, and the fluorescence change, as well as observing the morphology transition. The AIEgen-enabled multicolor visualization of the formation of SPNs may provide better understanding of the details of the crosslinking interactions in the microstructural evolution, giving more inspiration for the multifunctional products based on SPNs.

Luminescence and ESR dating of the sedimentary infill from the multi-level cave system of Alkerdi-Zelaieta (Navarre, N Spain)

The finding of Upper Paleolithic engravings in 2016 triggered a multidisciplinary investigation of the Alkerdi cave system (Urdazubi, N Spain). The study of the speleogenetic processes led to the identification of at least 6 paragenetic cave levels with associated sedimentary infill. In order to unravel the timing of changes in the karst dynamics and to get some insights about sediment origin, two sediment samples were collected from cave levels 4 and 1 for numerical dating purpose, using both Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR) methods. One additional modern-age sample was also taken from the entrance of the karst to evaluate the magnitude of the optical bleaching achieved by the quartz grains before entering the cave system. Last, one sample was collected from a flowstone for U-series dating, providing independent age control. OSL measurements were carried out using small quartz multi-grain (MG) and single-grain (SG) Single Aliquot Regenerative-dose (SAR) protocol. Initial Equivalent Dose (D e ) results show evidence of saturated OSL signal for the sample of the higher level (with ∼60% of saturated aliquots). Unlike SA data, SG analyses do not meet the usual quality criteria (e.g., relatively high recuperation ratios, only a few grains with useable signal), suggesting that corresponding dating results should be treated with caution. Hence, both MG and SG TT-OSL and MG ESR methods were subsequently employed, as the corresponding signals are known to have higher saturation levels than OSL ones. ESR analyses were based on the Multiple Centre (MC) approach using the standard multi-grain multi-aliquot additive (MAA) dose method, while TT-OSL measurements were performed following Demuro et al. (2020). The latter, however, did not return any useful results for both samples. MC ESR data show the usual D e pattern (D e (Al)>D e (Ti op. D)>D e (Ti–H)) indicating that among the three ESR signals analyzed, the Ti–H most likely provides the closest estimate to the true burial age. However, low measurement repeatability and goodness-of-of fit indicate that the reliability of the ESR results may be reasonably questioned. Results derived from this multi-technique dating approach provide the first chronological constraints for the sedimentary infill of the Alkerdi cave system. In particular, they suggest that sediment deposition in Cave Level 4 (ALK-OSL01) occurred around 130 ka, which is in good agreement with the minimum age constraint given by the speleothem (80.5 ± 9.0 ka). In comparison, the young age obtained for sample ALK-OSL02 (5.0 ± 0.9 ka) suggests recent Holocene formation of the lowest cave level 1. Finally, the MG De value obtained for the modern sample is close to zero (<1 Gy), indicating that the OSL signal is almost fully reset at a multi-grain level before entering the cave. Additionally, despite the large De overdispersion measured in this modern sample, the De values are one to two order of magnitude lower than those obtained with the same model in the other two samples. Therefore, the large OSL D e overdispersion (OD) values of up to 64% obtained for the two samples from Cave Level 4 and 1 are most likely related to re-sedimentation processes inside the cave system.

Luminescence and defects creation processes in Bi3+-doped gallium garnets

Microcrystalline powders of Y3Ga5O12:Bi and Gd3Ga5O12:Bi are investigated by the X-ray diffraction, scanning electron microscopy, time-resolved photoluminescence, and thermally stimulated luminescence methods in a wide temperature range (4.2–500 K). The results are compared with those obtained recently for the Lu3Ga5O12:Bi powder. The presence of the ultraviolet (UV) emission of a Bi3+ ion and the visible (VIS) emission of an exciton localized around the Bi3+ ion is confirmed for all the investigated gallium garnets. The processes of photostimulated creation of electron and hole centers taking place under irradiation in the 4–6 eV energy range are investigated. The origin of the hole centers responsible for the UV and VIS electron recombination luminescence is clarified. Electron transitions between the energy levels of Bi3+ ions and the Bi3+ → Ga3+oct, Bi3+ → Ga3+tetr, and Bi3+ → Y3+ or Bi3+ → Gd3+ electron transfer transitions are found to appear in the photo- and thermoluminescence excitation spectra. The Bi3+ energy level positions in the band gap are determined. Their influence on the luminescence and photostimulated creation of electron and hole centers is discussed.

A pedogenically-informed chronostratigraphic model elucidates the geochronology at the type site of the Bohunician technocomplex

The Bohunician, a Moravian variant of the broader Initial Upper Palaeolithic (IUP) lithic technocomplex, is thought to have arisen during the transition from the Middle to the Upper Palaeolithic in the ‘contact zone’ between the first anatomically modern humans and local Neanderthals. Attempts to date the Bohunician occupation at the eponymous site of Brno-Bohunice using luminescence and radiocarbon methods have yielded contradictory results. We propose a new perspective of the chronological position and taphonomy of the Bohunician finds based on a revaluation of published radiometric and luminescence data from the Brno-Bohunice site according to an updated radiocarbon calibration curve and recently revised pedostratigraphy. Here, for the first time, we combined contradictionary results of various dating method into one chronostratigraphical model of the site. The Bayesian model considers the discovery that the palaeosol(s) contemporary to most of the artefacts is (are) missing and the actual position was affected by frost-heaving processes. The onset of the Bohunician technocomplex is therefore placed most probably as early as ∼50 ka cal BP (the end of GI 14) and shows that it existed mainly during the interstadials GI 13 and GI 12. Nevertheless, the broad timespan of unmodelled thermoluminescence dates indicates a possible persistence of the last practitioners of Bohunician technology until ∼42 ka cal BP (GI 11), when development of a Cambisol horizon took place. Our model has two possible explanations: The first wave of anatomically modern humans (with or without Neanderthal introgression) arrived in Central Europe before GI 12, or the Bohunician technocomplex is connected with the local Neanderthal population.

Guide for interpreting and reporting luminescence dating results

The development and application of luminescence dating and dosimetry techniques have grown exponentially in the last several decades. Luminescence methods provide age control for a broad range of geological and archaeological contexts and can characterize mineral and glass properties linked to geologic origin, Earth-surface processes, and past exposure to light, heat, and ionizing radiation. The applicable age range for luminescence methods spans the last 500,000 years or more, which covers the period of modern human evolution, and provides context for rates and magnitudes of geological processes, hazards, and climate change. Given the growth in applications and publications of luminescence data, there is a need for unified, community-driven guidance regarding the publication and interpretation of luminescence results. This paper presents a guide to the essential information necessary for publishing and archiving luminescence ages as well as supporting data that is transportable and expandable for different research objectives and publication outlets. We outline the information needed for the interpretation of luminescence data sets, including data associated with equivalent dose, dose rate, age models, and stratigraphic context. A brief review of the fundamentals of luminescence techniques and applications, including guidance on sample collection and insight into laboratory processing and analysis steps, is presented to provide context for publishing and data archiving.

Development of BeO:Na,Yb,Dy ceramics for optically stimulated luminescence dosimetry

This paper presents the structural and luminescence characterization of undoped and trivalent lanthanide-doped BeO ceramics synthesized via the co-precipitation synthesis technique. Phase confirmation of the products was achieved by the x-ray diffraction (XRD) method, while the surface and elemental morphology were carried out with scanning electron microscopy (SEM)/energy dispersive spectrum (EDS) analyses. Radioluminescence (RL), Thermoluminescence (TL) and Optically stimulated luminescence (OSL) methods were utilized for the luminescence characterization. Moreover, the relationship between TL and OSL signals was investigated in-depth with three different experiments (TL after OSL, step annealing and thermally-transferred OSL (TT-OSL).The radiation sensitivity of BeO:Na5%,Yb0.2%,Dy0.01% ceramics was found to be high as a peak OSL signal of 1.3 × 104 counts/mg for 0.2 Gy beta dose. A wide green emission band between 475 and 625 nm was detected for the first time in the RL emission spectra of doped/undoped BeO ceramics. It has been found that the RL and TL emissions of BeO ceramics have partially similar luminescence mechanisms and the TL traps responsible for the ∼315 °C TL peak are the main source of OSL signals. The Tm-Tstop method, Eac-Tstop graph and deconvolution of TL glow curve have been conjunctionally used to estimate kinetic parameters of TL traps in BeO:Na5%,Yb0.2%,Dy0.01% pellets. The results demonstrate that the TL glow curve has at least five TL peaks at 172 ± 2, 223 ± 2, 316 ± 2, 356 ± 2 and 465 ± 2 °C with estimated activation energies 1.13, 1.16, 1.39, 1.41, and 1.99 eV, respectively. The dosimetric characteristics of BeO:Na5%,Yb0.2%,Dy0.01% pellets have been also performed by reusability, dose-response, and fading experiments, and the results show that the material is promising and encouraging for use in dosimetric applications.

The enhancement of exciton-like luminescence in KCl single crystals under local and uniaxial elastic lattice deformation

Radiative annihilation of exciton-like formations (bound excitons) in KCl single crystals doped with various impurity cations (Li, Na, Sr) has been studied using highly sensitive luminescence methods. In KCl:Na with different sodium concentration, X-ray luminescence bands with the maxima at 2.8 and 3.1 eV, which and attributed to exciton-like formations in the region of local lattice deformation by single Na+ and pair Na+-Na+ centers, become significantly more intense with sodium impurity concentration. The luminescence efficiency of such bound anion excitons also increases in the KCl:Na crystals exposed to a uniaxial elastic stress along the 〈100〉 and 〈110〉 crystallographic directions. The influence of temperature as well as lattice symmetry lowering due to applied elastic deformation (external action) or local deformation in the vicinity of impurity ions (internal action) on the efficiency of the recombination formation of bound excitons has been analyzed.

Quartz luminescence sensitivity from sediment versus bedrock in highly weathered soils of the Piedmont of North Carolina, south-eastern USA

Deeply weathered soils cover most of the Piedmont physiographic province of the south-eastern United States of America (USA). These soils have traditionally been inferred to derive from weathered bedrock, but recent work (e.g. Ferguson et al., 2019) suggests that deposited sediments are more prevalent than recognized. Distinguishing sediment from weathered bedrock is integral to understanding critical-zone processes and overall Quaternary landscape evolution, yet the well-developed, red, clay-dominated Ultisols of this temperate and humid region mask differences between transported from non-transported material. Our goal is to determine if optically stimulated luminescence (OSL) methods can distinguish quartz sand from allochthonous (e.g. transported sediment) versus autochthonous (e.g. in situ weathered bedrock) material in soil-profile and core samples from the Redlair Observatory in southwestern North Carolina, USA. Here, we turn to OSL sensitivity and linear-modulated OSL (LM-OSL) to observe the intensity or lack thereof of the fast-decay luminescence component (most light-sensitive signal) in quartz grains from soil horizons and crystalline bedrock-derived saprolite. We find that quartz grains sampled from in situ weathered bedrock as well as from saprolotized clasts of rock have weak luminescence properties and are not dominated by a fast-decay luminescence component. In contrast, quartz grains from transported sediment (e.g. mobile regolith; colluvium; alluvium) contain sensitive grains with more dominant fast components. These results suggest that quartz luminescence sensitivity can be a tool to differentiate between in situ weathered bedrock and similar looking mobile regolith and colluvium over-printed by soil development.

Structural characterization, continuous-wave optically stimulated luminescence, and correlation between thermoluminescence and EPR of Ce-doped Ca2Al2SiO7 phosphor synthesized by a solid-state reaction method

A calcium aluminum silicate (Ca2Al2SiO7) phosphor doped with different concentrations of cerium has been prepared by a solid-state reaction method. From X-ray diffraction (XRD) data and using the Rietveld refinement method, the phase, structure, and average crystalline size have been determined. Luminescence emissions have been investigated by optically stimulated luminescence (OSL) and thermoluminescence (TL) methods. TL studies reveal a broad peak centered at 220 °C with an emission band at 410 nm. The TL intensity of a sample doped with 0.1 mol% Ce proved to be 115 times stronger than that of an undoped sample. Electron paramagnetic resonance (EPR) has been utilized to detect the defect centers responsible for the TL process in Ce-doped Ca2Al2SiO7 phosphor. The observed EPR spectrum results from a superposition of three defect centers. Center I with a g-value of 2.0090 is assigned to an O− ion and exhibits hyperfine interaction with a nearby nucleus with spin 3/2. This center relates to the TL peak at 220 °C. Center II with an isotropic g-value of 2.0073 is also ascribed to an O− ion and correlates with the dominant 220 °C TL peak. Center III has a g-value of 2.0076 and is identified as an F+ center (singly-ionized oxygen vacancy).

Excited state dynamics in Bi3+-doped lutetium gallium garnet

Microcrystalline powders of Bi3+-doped Lu3Ga5O12 garnet are investigated by the X-ray diffraction, time-resolved luminescence spectroscopy, and thermally stimulated luminescence methods. The mechanisms of the processes are clarified, which take place in the excited states of the Bi3+-related luminescence centers and result in the appearance of two (ultraviolet and visible) emission bands with strongly different characteristics in the photo- and thermoluminescence spectra as well as in the creation of stable electron and hole centers of different types. The conclusion is made that besides the electron transitions between the Bi3+ levels, the photoexcitation of Lu3Ga5O12:Bi results in the ionization of Bi3+ and in the Bi3+ → Ga3+oct, Bi3+ → Ga3+tetr, and Bi3+ → Lu3+ electron transfer transitions. These processes can lead to the release of free electrons into the conduction band, their trap at different electron traps, and formation of hole centers of the type of Bi4+ and {O- - Bi3+}. The recombination of electrons with these hole centers results in the ultraviolet emission of a Bi3+ ion and visible emission of an exciton localized around the Bi3+ ion, respectively.

Analysis of Methods for Diagnosing the Aromatic Groups Fraction in Transformer Oils

This review describes one of transformer oil degradation mechanisms - an increase in the fraction of aromatic compounds during the operation of oil-filled electric power equipment. The influence of such substances on the properties and characteristics of oils used in the power system of the Russian Federation, and the features relating to the operation of oil filled transformers with an increased fraction of arenes are discussed. The need to monitor the fraction of aromatic compounds in transformer oils is substantiated. The known qualitative and quantitative analysis methods suitable for this purpose (Nastyukov reaction, mass spectroscopy, ultraviolet spectroscopy, infrared spectroscopy, nuclear magnetic resonance, Raman scattering, chromatography, luminescence, and the nomogram method) are listed. The paper gives brief characteristics of the parameters by which the fraction of aromatic groups in transformer oil is determined. The advantages and disadvantages of each method are analyzed with taking into account the features of the systems under study. It is concluded that infrared spectroscopy and 1H and 13C nuclear magnetic resonance are the most promising ones for monitoring the content of aromatic substances in transformer oil, whereas the use of Raman scattering and luminescence methods requires further research and development for being applied in transformer oil analysis procedures.

Vegetation History and Survival Patterns of the Earliest Village on the Qinghai-Tibetan Plateau.

The upper Yellow River valley in the northeastern Qinghai–Tibetan Plateau (QTP) is an important corridor for prehistoric migration to the hinterland plateau. However, most studies have focused on the Neolithic Age, with limited evidence for earlier periods. The Shalongka (SLK) site on the northeastern QTP spans the Epipaleolithic to Bronze Age and contains cultural deposits, so provides a good basis for unraveling the evolutionary history of the human-land relationship. In this study, we sampled the 420-cm-thick section T1406E at the SLK site and undertook lithologic stratigraphic description and analysis of grain size, redness, magnetic susceptibility, geochemical elements, pollen and charcoal. Dating control was provided by accelerated mass spectrometry 14C and optically stimulated luminescence methods. Results show that SLK site was affected by the local fluvial sedimentary environment. The absolute dating results of the SLK site have revealed that humans occupied the site during the Epipaleolithic (8.5–7.3 cal ka BP), Yangshao culture (5.9–5.1 ka) and Qijia Culture (4.1–3.9 cal ka BP). Pollen analysis showed that the humans lived in a landscape that was predominated by forest-steppe. Consolidating with multidisciplinary evidence, we learned that Epipaleolithic sites were occupied by microlithic hunter-gatherers and comprised by relatively fixed seasonal central campsites, and their mobility was significantly decreased from the early to late period. Subsequently, farmers of the Yangshao culture migrated from the low elevation (Chinese Loess Plateau) to the upper Yellow River valleys on the QTP and founded the earliest settlement villages (~5.9 ka) on the QTP. People of the Qijia culture adopted diversified survival strategies under the settled lifestyle. In all, we infered that SLK site may play an important role in the communication and integration between different people and cultures.