Single Exponential Function Research Articles

Synthesis and luminescent properties of CaLa2ZnO5:Ln (Ln:Tm3+ or Er3+) phosphors

Tm3+ or Er3+ ions individually doped CaLa2ZnO5 (CLZO) phosphors were synthesized by a citrate sol–gel method. The phase formation and morphological properties of these phosphors were analyzed by X-ray powder diffraction patterns and scanning electron microscope images, respectively. Under ultraviolet (UV) or near UV light excitations, the luminescence properties of these phosphors were studied as a function of Tm3+ or Er3+ ion concentration. Likewise, cathodoluminescence properties were measured as a function of accelerating voltage and filament current. The CLZO:Tm3+ phosphor revealed the intense blue emission due to the 1D2→3F4 electronic transition and the CLZO:Er3+ phosphor exhibited the green emission due to the 4S3/2→4I15/2 electronic transition. The decay curves of these phosphors were well fitted to a single exponential function. The chromaticity coordinates were calculated for the synthesized CLZO:Tm3+ and CLZO:Er3+ phosphors.

Three Pseudomonas putida FNR Family Proteins with Different Sensitivities to O2

The Escherichia coli fumarate-nitrate reduction regulator (FNR) protein is the paradigm for bacterial O2-sensing transcription factors. However, unlike E. coli, some bacterial species possess multiple FNR proteins that presumably have evolved to fulfill distinct roles. Here, three FNR proteins (ANR, PP_3233, and PP_3287) from a single bacterial species, Pseudomonas putida KT2440, have been analyzed. Under anaerobic conditions, all three proteins had spectral properties resembling those of [4Fe-4S] proteins. The reactivity of the ANR [4Fe-4S] cluster with O2 was similar to that of E. coli FNR, and during conversion to the apo-protein, via a [2Fe-2S] intermediate, cluster sulfur was retained. Like ANR, reconstituted PP_3233 and PP_3287 were converted to [2Fe-2S] forms when exposed to O2, but their [4Fe-4S] clusters reacted more slowly. Transcription from an FNR-dependent promoter with a consensus FNR-binding site in P. putida and E. coli strains expressing only one FNR protein was consistent with the in vitro responses to O2. Taken together, the experimental results suggest that the local environments of the iron-sulfur clusters in the different P. putida FNR proteins influence their reactivity with O2, such that ANR resembles E. coli FNR and is highly responsive to low concentrations of O2, whereas PP_3233 and PP_3287 have evolved to be less sensitive to O2.

Photochemical Property and Photodynamic Activity of Tetrakis(2-naphthyl) Porphyrin Phosphorus(V) Complex

Photochemical Property and Photodynamic Activity of Tetrakis(2-naphthyl) Porphyrin Phosphorus(V) Complex

Temporal behavior of the singlet molecular oxygen emission in imidazolium and morpholinium ionic liquids and its implications.

The solvent effect of ionic liquids on the lifetime of singlet molecular oxygen, O2((1)Δg), was investigated by means of time-resolved near-IR emission spectroscopy. O2((1)Δg) was generated by photosensitization of methylene blue in morpholinium and imidazolium ionic liquids, both comprising various alkyl chains of different lengths. The measured time profiles of O2((1)Δg) luminescence for the (1)Δg → (3)Σg(-) transition were represented by a single-exponential decay function. The phosphorescence lifetime was found to be correlated with the alkyl chain length of the morpholinium ionic liquids. This observation was interpreted by considering efficient quenching of O2((1)Δg) through energy transfer to the high-frequency C-H stretching modes of the N-alkyl chain in the morpholinium cation. Interestingly, we found that O2((1)Δg) quenching by the C-H stretching modes of the ring of the cations was remarkably depressed. The kinetics of the O2((1)Δg) emission decay process was discussed on the basis of the heterogeneous structure of ionic liquids consisting of polar and nonpolar domains.

Ultrafast Intramolecular Electron and Proton Transfer in Bis(imino)isoindole Derivatives.

Concerted motion of electrons and protons in the excited state is pertinent to a wide range of chemical phenomena, including those relevant for solar-to-fuel light harvesting. The excited state dynamics of small proton-bearing molecules are expected to serve as models for better understanding such phenomena. In particular, for designing the next generation of multielectron and multiproton redox catalysts, understanding the dynamics of more than one proton in the excited state is important. Toward this goal, we have measured the ultrafast dynamics of intramolecular excited state proton transfer in a recently synthesized dye with two equivalent transferable protons. We have used a visible ultrafast pump to initiate the proton transfer in the excited state, and have probed the transient absorption of the molecule over a wide bandwidth in the visible range. The measurement shows that the signal which is characteristic of proton transfer emerges within ∼710 fs. To identify whether both protons were transferred in the excited state, we have measured the ultrafast dynamics of a related derivative, where only a single proton was available for transfer. The measured proton transfer time in that molecule was ∼427 fs. The observed dynamics in both cases were reasonably fit with single exponentials. Supported by the ultrafast observations, steady-state fluorescence, and preliminary computations of the relaxed excited states, we argue that the doubly protonated derivative most likely transfers only one of its two protons in the excited state. We have performed calculations of the frontier molecular orbitals in the Franck-Condon region. The calculations show that in both derivatives, the excitation is primarily from the HOMO to LUMO causing a large rearrangement of the electronic charge density immediately after photoexcitation. In particular, charge density is shifted away from the phenolic protons and toward the proton acceptor nitrogens. The proton transfer is hypothesized to occur both due to enhanced acidity of the phenolic proton and enhanced basicity of the nitrogen in the excited state. We hope this study can provide insight for better understanding of the general class of excited state concerted electron-proton dynamics.

Structural and spectroscopic characteristics of Eu3+-doped tungsten phosphate glasses

Tungsten based phosphate glasses are interesting non-crystalline materials, commonly known for photochromic and electrochromic effects, but also promising hosts for luminescent trivalent rare earth ions. Despite very few reports in the literature, association of the host́s functionalities with the efficient emissions of the dopant ions in the visible and near-infrared spectra could lead to novel applications. This work reports the preparation and characterization of glasses with the new composition 4(Sb2O3)96−x(50WO3 50NaPO3)xEu2O3 where x=0, 0.1, 0.25, 0.5 and 1.0mol%, obtained by the melt quenching technique. The glasses present large density (∼4.6gcm−3), high glass transition temperature (∼480°C) and high thermal stability against crystallization. Upon excitation at 464nm, the characteristic emissions of Eu3+ ions in the red spectral region are observed with high intensity. The Judd–Ofelt intensity parameters Ω2=6.86×10−20, Ω4=3.22×10−20 and Ω6=8.2×10−20cm2 were calculated from the emission spectra and found to be higher than those reported for other phosphate glass compositions. An average excited state lifetime value of 1.2ms, was determined by fitting the luminescence decay curves with single exponential functions and it is comparable or higher than those of other oxide glasses.

Crystal structure, morphology and luminescent properties of rare earthion-doped SrHPO4 nanomaterials

Undoped and rare earth ions (Eu3+, Ce3+, Tb3+) doped β-SrHPO4 nanomaterials were successfully prepared by a facile hydrothermal method. The crystal structure, morphology and luminescent properties were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra and luminescence decay curves. The results indicated that the undoped and rare earth ions doped SrHPO4 nanomaterials (the doping concentration was not above 7%) were well crystallized, with the same crystal structure (β-SrHPO4). Nevertheless, the doping of rare earth ions could lead to the changing of morphology from nanoflakes to nanocrystals. Under the excitation of UV light, rare earth ions (Eu3+, Ce3+, Tb3+) doped β-SrHPO4 nanocrystals exhibited the characteristic emission of Eu3+, Ce3+ and Tb3+ ions, respectively. The luminescence decay curves of β-SrHPO4:Eu3+ and β-SrHPO4:Ce3+,Tb3+ nanocrystals conformed to the double exponential fluorescence decay, and the average lifetimes were 1.14 and 4.12 ms, respectively. The luminescence decay curve of β-SrHPO4:Ce3+ was fitted into a single exponential function, and the lifetime was about 0.78 ns.

Dynamic regulation of a cell adhesion protein complex including CADM1 by combinatorial analysis of FRAP with exponential curve-fitting.

Protein components of cell adhesion machinery show continuous renewal even in the static state of epithelial cells and participate in the formation and maintenance of normal epithelial architecture and tumor suppression. CADM1 is a tumor suppressor belonging to the immunoglobulin superfamily of cell adhesion molecule and forms a cell adhesion complex with an actin-binding protein, 4.1B, and a scaffold protein, MPP3, in the cytoplasm. Here, we investigate dynamic regulation of the CADM1-4.1B-MPP3 complex in mature cell adhesion by fluorescence recovery after photobleaching (FRAP) analysis. Traditional FRAP analysis were performed for relatively short period of around 10min. Here, thanks to recent advances in the sensitive laser detector systems, we examine FRAP of CADM1 complex for longer period of 60 min and analyze the recovery with exponential curve-fitting to distinguish the fractions with different diffusion constants. This approach reveals that the fluorescence recovery of CADM1 is fitted to a single exponential function with a time constant (τ) of approximately 16 min, whereas 4.1B and MPP3 are fitted to a double exponential function with two τs of approximately 40-60 sec and 16 min. The longer τ is similar to that of CADM1, suggesting that 4.1B and MPP3 have two distinct fractions, one forming a complex with CADM1 and the other present as a free pool. Fluorescence loss in photobleaching analysis supports the presence of a free pool of these proteins near the plasma membrane. Furthermore, double exponential fitting makes it possible to estimate the ratio of 4.1B and MPP3 present as a free pool and as a complex with CADM1 as approximately 3:2 and 3:1, respectively. Our analyses reveal a central role of CADM1 in stabilizing the complex with 4.1B and MPP3 and provide insight in the dynamics of adhesion complex formation.

Analyzing surface plasmon resonance data: choosing a correct biphasic model for interpretation.

Surface plasmon resonance (SPR) has been widely used as a label-free biophysical technique to quantitatively study biochemical processes. For the SPR data fitting using a single exponential function, the procedure to extract the rate constants is straightforward. However, there is no simple procedure for SPR data fitting with double exponential functions. A highly non-linear fitting procedure is, therefore, used to fit the biphasic SPR data with numerical solutions of the rate equations. This procedure requires some prior knowledge of the underlying interaction mechanism, and the extracted rate constants often have large uncertainties. In this report, we propose a new method of analyzing the biphasic SPR data using the three commonly employed biphasic models. Our method is based on a general analytical solution of the biphasic rate equations, which is much more transparent and straightforward than the highly non-linear numerical integration approach. Our method can be used to determine the underlying biphasic interaction mechanism from the analysis of the SPR data and to extract the rate constants with high confidence levels. We have illustrated the procedures with examples of the data analysis on simulated SPR profiles, and the results are discussed.

THE STRUCTURE AND STELLAR CONTENT OF THE OUTER DISKS OF GALAXIES: A NEW VIEW FROM THE Pan-STARRS1 MEDIUM DEEP SURVEY

We present the results of an analysis of Pan-STARRS1 Medium Deep Survey multi-band (grizy) images of a sample of 698 low-redshift disk galaxies that span broad ranges in stellar mass, star-formation rate, and bulge/disk ratio. We use population synthesis spectral energy distribution fitting techniques to explore the radial distribution of the light, color, surface mass density, mass/light ratio, and age of the stellar populations. We characterize the structure and stellar content of the galaxy disks out to radii of about twice Petrosian r90, beyond which the halo light becomes significant. We measure normalized radial profiles for sub-samples of galaxies in three bins each of stellar mass and concentration. We also fit radial profiles to each galaxy. The majority of galaxies have down-bending radial surface brightness profiles in the bluer bands with a break radius at roughly r90. However, they typically show single unbroken exponentials in the reddest bands and in the stellar surface mass density. We find that the mass/light ratio and stellar age radial profiles have a characteristic "U" shape. There is a good correlation between the amplitude of the down-bend in the surface brightness profile and the rate of the increase in the M/L ratio in the outer disk. As we move from late- to early-type galaxies, the amplitude of the down-bend and the radial gradient in M/L both decrease. Our results imply a combination of stellar radial migration and suppression of recent star formation can account for the stellar populations of the outer disk.

Analytical investigations of thermoluminescence glow curve on quartz for luminescence dating

Investigations of bleaching and thermoluminescence (TL) response to radiation dose of quartz are importance in luminescence dating. Although such research has been extensively carried out for various types of quartz, most work was performed on the basis of TL intensity integrated for a particular temperature range on the glow curve, without any peak separation. In this study we investigated bleaching by a blue light stimulation and radiation dose behaviour for separated TL glow peaks of quartz, which are thermally stable, by using the computerized glow curve deconvolution (CGCD) method combined with the Tm–Tstop method. The Tm–Tstop method indicates that the glow curve of quartz is the superposition of at least seven components (P1–P7) in the temperature range between room temperature and 450 °C. A bleaching experiment for four thermally stable glow peaks (P4–P7) using a blue light stimulation revealed that the bleaching rate of peak P4 exhibits three different exponential decays, whereas the peaks P5, P6 and P7 are bleached with two different exponential decays. After bleaching of 12 h, the TL intensity of peaks P4, P5, P6 and P7 were reduced to approximately 6%, 16%, 26% and 68% of the initial value, respectively. Additionally, in a study of the radiation dose response of the four thermally stable glow peaks, all peaks have a similar pattern, which are well fitted by a single saturating exponential function.

Near-infrared luminescence of bismuth in fluorine-doped-core silica fibres.

Photoluminescence spectra and decay kinetics of bismuth inclusions in silica optical fibres containing fluorine additive in the core glass are studied in the vicinity of a wavelength of 1420 nm at temperatures of 80-900 K under a continuous wave (CW) and a pulsed diode laser pump at a wavelength of 808 nm. At high fluorine concentration and low temperatures, luminescence decay kinetics becomes essentially bi-exponential, typical lifetimes being 720 and 1200 µs. Hydrogen and deuterium loading at pressures of up to 125 bar leads to a decrease of the steady-state luminescence intensity and lifetime. We attribute this to the appearance of an energy transfer bridge from bismuth clusters to vibrational degrees of freedom of diatomic molecules. It is found that in the presence of H(2) or D(2) molecules experiencing random walking in silica, luminescence decay kinetics stop following a single exponential function even in fluorine-free silica-core fibre, deviation from the single exponent being greater at higher temperatures. The induced quenching rate increases with the increase of temperature as well and is greater for H(2) molecules. All conditions being equal, the equilibrium concentration of hydrogen molecules is greater in heavily fluorinated silica. At temperatures below ~250 K, the presence of dissolved molecules has no effect, which speaks for the primary importance of having rotational degrees of freedom of migrating interstitial diatomic molecules in an excited state for effective quenching of bismuth electronic excitations. It is found that the influence of dissolved deuterium is weaker than that of hydrogen. We attribute this feature to a greater angular momentum of the D(2) molecule and correspondingly smaller energy of the molecule's rotational quantum. The results of the experiments show that bismuth clusters mainly located in voids of the silica network, rather than bismuth point defects, are responsible for near-infrared luminescence.

An Exponential Melanoma Trend Model

The present study investigated whether whole population exposure to radiation introduced by radio broadcasting and cell phone systems might explain recent increases in melanoma trends in Nordic countries or not. Trends were modeled using a single exponential function of the time each age group has been living in the new environment since an environmental change took place. The results clearly show that melanoma incidences started to increase exponentially by the time lived as an adult since 1955 and that a second trend break occurred in 1997. We searched best fit between calculated and reported age-standardized rates by parameter variation, and compared calculated with reported age-specific rates without further parameter adjustments. Local variations of breast cancer, lung cancer and all cancers together significantly correlated with corresponding local melanoma rates in Sweden. Increasing cancer trends since around 1997 seem related to a population covering environmental change effective from early 90’s. We conclude that this exponential trend model can be a useful tool in understanding responses to sudden environmental changes.

UNILATERAL MINI NMR SENSOR USED FOR ASSESSING THE AGING STATUS OF THE SHEDS OF COMPOSITE INSULATORS

The number of composite insulators used in power transmission lines increases year by year. To detect and assess the aging status accurately concerns the security and stability of the power system. In order to achieve nondestructive testing of the sheds of composite insulators, a unilateral mini Nuclear Magnetic Resonance (NMR) sensor is proposed in this paper. The design of the magnet body and the optimization of the RF coil are presented. The Carr-Purcell-Meiboom-Gill (CPMG) sequence was employed to record the 1 H relaxation curves of the sheds of three composite insulators from 110 kv lines with different service years. The curves were fitted to both single exponential function and inverse Laplace transformation functions. The results demonstrate that an increase of service year of the insulator results in a decrease of the effective transverse relaxation time (T2eff ). It is indicated that the sensor has a potential to assess the aging status of the composite insulators.

Photodynamic Modification of Sea Urchin spHCN Channel

The hyperpolarization activated cyclic nucleotide gated ion channels (HCN channels) are nonspecific cation channels that play vital role in the generation of rhythmic activities in the brain and the heart. Among the various members of HCN channels, spHCN channel is unique in that it undergoes rapid inactivation following a hyperpolarizing voltage step and cAMP binding abolishes the inactivation. Previously, we had shown that mouse HCN2 channel can be modified by a photodynamic process that involves photosensitizer, oxygen and laser pulses. Here, we asked whether similar photodynamic process could modify spHCN channel. We applied 1µM FITC-conjugated cAMP to the intracellular side of the membrane patch. Application of short laser pulses abolished spHCN inactivation. The channel opening after the laser pulses can be fitted with a single-exponential function, with a time constant around 150msec. After 4-6 laser pulses (100 msec long), the macroscopic current reaches about 30% of maximal current, as determined in the presence of 10µM cAMP. Furthermore, we demonstrate that single point mutation from Histidine to Alanine (H462, located near the intracellular end of S6) eliminates the effects of laser modification. To further investigate the mechanism, we applied 100nM Rose Bengal, a widely used as an organic singlet oxygen generator and observed similar changes to channel activity which suggests that this is photodynamic transformation process that involves a photosensitizer and most likely the generation of singlet oxygen. Thus, together with our previous observation, with the photodynamic transformation of mouse HCN2 channel, we demonstrate that this photodynamic process could be applied to the invertebrate form of HCN channel. The reason for HCN channels to be highly sensitive to photodynamic transformation, most likely through generation of singlet oxygen and the corresponding physiological relevance are open question needed to be addressed in the future study.

Modal Gating of Muscle AChRs having Loop C Mutations

Many ion channels exhibit multiple patterns of kinetic activity (‘modes’) in single-channel currents. This behavior is rare in WT mouse muscle acetylcholine receptors (AChRs), where A2C↔A2O gating events are well-described by single exponentials. We have found that mutations of all loop C residues at the transmitter binding site (except αY190 and αY198) increase the probability of modes. The free energy of diliganded gating is the sum of that for unliganded gating and from agonist affinity-changes at 2 binding sites: ΔG2=ΔG0+2ΔGB. For WT adult AChRs these values are (−100 mV; kcal/mol): −1.9, +8.3 and −5.1 (ACh). All mutations of αP197 (ACDEGIKSVY) had at least 2 gating modes with all agonists (ACh, Cho, CCh and TMA). We focused on αP197A and ACh and Cho. There were 3 distinct modes at saturating [agonist] but only 1 mode without agonist. Hence, the kinetic heterogeneity for this construct is generated by fluctuations in ΔGB. ΔΔGB was estimated for each mode (kcal/mol) for ACh (−1.7, WT and +1.6) and Cho (−2.2, WT and +0.9). That is, the gating equilibrium constant for one mode was ∼30-times larger than the WT (for both agonists), for another was about the same as the WT and for the third was ∼8-times smaller. An added F mutation at αY190 or αW149 reduced modal gating whereas one at αY198 or αY93 did not. An F substitution at eW55 had no effect, but one at δW57 reduced the modes. We also examined AChRs having only 1 active binding site and observed less heterogeneity from αP197A at the fetal α-γ site vs. the adult α-e or α-δ sites. Our working hypothesis is that mutations in loop C allow the agonist to sample multiple, meta-stable positions within the binding pocket, to produce distinct ΔGB values.

On the use of Simple Moving Averages for supply chains where information is not shared

Despite the evidence of benefits of information sharing, there are many supply chains that are unable to share information due to constraints such as compatibility of information systems, information quality, trust and confidentiality. Furthermore, a steady stream of papers has explored a phenomenon known as Downstream Demand Inference (DDI) where the upstream member in the supply chain can infer the downstream demand without the need of a formal information sharing mechanism. Recent research has shown that under a more practical setting, with less restrictive assumptions, DDI is not possible with optimal forecasting methods or Single Exponential Smoothing but is possible when supply chains use a Simple Moving Average (SMA) method. In this paper, we propose a simple DDI strategy based on SMA for supply chains where information cannot be shared. This strategy allows the upstream member in the supply chain to infer the consumer demand mathematically rather than sharing this. We compare the DDI strategy with the existing No Information Sharing (NIS) strategy. The comparison is made analytically which enables to show that using the DDI strategy reduces the MSE in the supply chains.

OSL dating of fine and coarse quartz from a Palaeolithic sequence on the Bistrița Valley (Northeastern Romania)

Previous works focused on optically stimulated luminescence dating of quartz extracted from Romanian and Serbian loess reported significant discrepancies between ages obtained on fine (4–11 μm) and coarse (63–90 μm) quartz. The present study is directed at expanding these investigations. The SAR-OSL and double SAR-OSL protocols are applied on quartz of different grain sizes belonging to 9 samples extracted from a newly identified archaeological site at Bistricioara-Lutărie III on the Bistrița Valley (NE Romania). Radiocarbon ages are also obtained for the 3 uppermost cultural layers hosted in the loess-like deposit.Discrepant ages are obtained between fine (4–11 μm) and coarse (63–90 and 90–200 μm, respectively) quartz for equivalent doses higher than ∼80–100 Gy. However, a very good agreement is achieved for the youngest sample, with an age of ∼8 ka (with a De of 38 Gy for fine and 35 Gy for coarse grains, respectively). The comparison with independent control provided by radiocarbon dating suggests better agreement of ages calculated for coarse quartz. Our results are once again proof that concerns should be raised regarding the reliability of the equivalent doses obtained on quartz samples for which the laboratory dose response cannot be fitted by a single saturating exponential function. Further systematic investigations are required regarding the very different saturation characteristics of fine and coarse grained quartz.

Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation.

We study theoretically the kinetics of mRNA translocation in the wild-type (WT) Escherichia coli ribosome, which is composed of a small 30S and large 50S subunit, and the ribosomes with mutations to some intersubunit bridges such as B1a, B4, B7a, and B8. The theoretical results reproduce well the available in vitro experimental data on the biphasic kinetics of the forward mRNA translocation catalyzed by elongation factor G (EF-G) hydrolyzing GTP, which can be best fit by the sum of two exponentials, and the monophasic kinetics of the spontaneous reverse mRNA translocation in the absence of the elongation factor, which can be best fit by a single-exponential function, in both the WT and mutant ribosomes. We show that both the mutation-induced increase in the maximal rate of the slow phase for the forward mRNA translocation and that in the rate of the spontaneous reverse mRNA translocation result from a reduction in the intrinsic energy barrier to resist the rotational movements between the two subunits, giving the same degree of increase in the two rates. The mutation-induced increase in the maximal rate of the fast phase for the forward mRNA translocation results mainly from the increase in the rate of the ribosomal unlocking, a conformational change in the ribosome that widens the mRNA channel for the mRNA translocation to take place, which could be partly due to the effect of the mutation on the intrasubunit 30S head rotation. Moreover, we study the translation rate of the WT and mutant ribosomes. It is shown that the translation rate versus the concentration of EF-G-GTP does not follow the Michaelis-Menten (MM) kinetics, which is in sharp contrast to the general property of other enzymes that the rate of the enzymatic reaction versus the concentration of a substrate follows the MM kinetics. The physical origin of this non-MM kinetics for the ribosome is revealed.

Structure determination and optical properties of CsSm(PO3)4

A new alkali metal-rare earth polyphosphate CsSm(PO3)4 has been synthesized by flux method. The obtained compound has been characterized by means of single crystal X-ray diffraction, Fourier transform infrared (FTIR) and Raman scattering spectroscopies. It crystallizes in the monoclinic space group P21/n with the following unit-cell parameters: a=10.382(2), b=8.978(6), c=11.205(4)Å, β=106.398(3)° and Z=4. The structure of CsSm(PO3)4 is an infinite three-dimensional framework made up of double spiral (PO3)n chains linked with neighboring SmO8 and CsO11 polyhedra. Spectroscopic properties of Sm3+ in this new compound including excitation, emission, and kinetic measurement have been performed. The emission spectrum shows four transitions characteristics of Sm3+ in the orange–red region by excitation wavelength at 400nm. The decay time curve of 4G5/2→6H7/2 transition has been also registered and fitted to a single exponential function.