Erbium Levels Research Articles

Structural, thermal and spectroscopic properties of Er2O3-doped oxyfluoro tellurophosphate glasses

Employing the melt quench method, the oxyfluoro tellurophosphate glasses (PTBMEr), doped with varying erbium concentrations, were prepared. Their physical, structural, optical, and luminescent characteristics were investigated using XRD, EDX, FTIR, absorption and Photoluminescence studies. The amorphous nature and elemental composition were identified using the XRD and EDX spectra. The J-O parameters and radiative parameters, including energy gap (ΔE), branching ratio (βR), radiative lifetime (τrad), and radiative transition probability (AR), were established for different excited levels of erbium in PTBMEr glass matrices. The visible emission spectra were acquired through excitation at a wavelength of 377 nm, resulting in a highly pronounced emission band at 544 nm, corresponding to the transition 4S3/2→ 4I15/2. The NIR emission spectra obtained through excitation at 980 nm showed a prominent broad emission band at 1534 nm pertaining to the transition 4I13/2→4I15/2. Within the set of prepared samples, the PTBMEr05 sample exhibits highest stimulated emission cross section of 0.75 × 10-20 cm2 for the transition 4S3/2→4I15/2. It also exbited superior parameters for the transition 4S3/2→4I15/2 including a stimulated emission crosssection of 1.19 × 10-20 cm2, gain bandwidth of 64.87 × 10-25 cm3, and optical gain of 53.41 × 10-24 cm2s. Experimental lifetime values for the excited level 4I13/2 of erbium in PTBMEr glasses were calculated and found to decrease with concentration due to non-radiative mechanisms and concentration quenching. These results reflect that PTBMEr05 glass is best suited for green laser emission devices and optical fiber communication windows.

Study on synergistic effects of 4f levels of erbium and black phosphorus/SnNb2O6 heterostructure catalysts by multiple spectroscopic analysis techniques.

Lanthanide single atom modified catalysts are rarely reported because the roles of lanthanide in photocatalysis are difficult to explain clearly. Based on the construction of Er single atom modified black phosphorus/SnNb2O6 (BP/SNO) heterojunctions, the synergistic effect of 4f levels of Er and heterostructures was studied by combining steady-state, transient, and ultrafast spectral analysis techniques with DFT theoretical calculations. According to the Judd-Ofelt theory of lanthanide ions, the CO2 photoreduction test under single wavelength excitation verifies that the 4F7/2/2H11/2 → 4I15/2 emissions of Er in BPEr/SNOEr can be more easily absorbed by SNO and BP, further proving the role of the 4f levels. As a result, the CO and CH4 yields of BPEr/SNOEr-10 under visible light irradiation are 10.7 and 10.1 times higher than those of pure BP, respectively, and 3.4 and 1.5 times higher than those of SNO. The results of DFT calculations show that the Er single atoms can cause surface reconstruction, regulate the active sites of BP, and reduce the energy change value in the key steps (CO2* + H+ + e- → COOH* and COOH* → CO* + H2O). This work provides novel insights into the design of lanthanide single atom photocatalysts for CO2 reduction.

Quantification of the resonant energy transfer processes in Er3+/Yb3+ co-doped Ca3Al2Si3O12 glasses

The resonant cross relaxation processes between Yb3+ and Er3+ ions in calcium alumino-silicate glasses have been quantified under selective Er3+ excitation. The infrared emission spectra, measured under steady state conditions (CW excitation to the 4I9/2 erbium level), have allowed to obtain an experimental relationship linking the transfer (Yb3+ → Er3+) and back transfer (Er3+ → Yb3+) parameters. These measurements combined with the dynamics of the main emitting levels, measured under pulsed excitation to the 2H11/2 erbium level, have allowed the fully quantification of the energy transfer parameters. The obtained values, C25=5.5×10−18cm3s−1 (Yb3+ → Er3+), C52=1.5×10−18cm3s−1 (Er3+ → Yb3+) and C27=7.6×10−18cm3s−1 (up-conversion mechanism, estimated from the Judd-Ofelt analysis previously reported), can be used to predict the temporal evolution of the main luminescent emission bands.

Excitation power density dependence of a primary luminescent thermometer based on Er3+, Yb3+: GdVO4 microcrystals operating in the visible

A discussion about the calibration of the Er3+,Yb3+:GdVO4 microcrystals as a luminescent primary thermometer based on the known equation of state of Boltzmann distribution of the electronic population of the two Erbium emitting coupled levels has been given. Its validity has been demonstrated. Besides, when Er3+,Yb3+:GdVO4 microcrystals acting as secondary thermometer, it has been proven the dependence of the thermometric ratio based on the integrated intensities of the green visible emissions arising from the two thermally coupled levels of erbium, 2H11/2 and 4S3/2, on the excitation power density for the Er3+,Yb3+:GdVO4 microcrystals. The effect of the excitation power density on the relative thermal sensitivity and temperature resolution has been also analyzed.

Synthesis and Laser-Related Spectroscopy of Er:Y2O3 Optical Ceramics as a Gain Medium for In-Band-Pumped 1.6 µm Lasers

In this paper, Er:Y2O3 optical ceramics were fabricated and details of the synthesis were presented. The spectral–luminescent properties of Er3+:Y2O3 optical ceramics were investigated. The absorption and emission cross-section spectra were determined. The luminescence kinetics at near 1.6 µm was single exponential and the lifetime of erbium 4I13/2 energy level was determined. In the frame of the conventional Judd–Ofelt theory, the emission properties of the energy levels of erbium 4I13/2 and 4I11/2 involved in laser operation at near 1.6 µm were calculated. The gain coefficient curves for typical values of the relative population of the upper laser level 4I13/2 were presented. The composition and structure were studied using the SEM, XRD, FTIR spectroscopy, and X-ray computer tomography techniques.

Mathematical Modelling of Einstein’s Rate Equations for Zinc Phosphate Glass with Er<sup>3+</sup>-Yb<sup>3+</sup>

There is a constant growth in the demand of data information transmission capacity, that is, more and more people send data, voice, video signals, among others, through communications networks. Due to the above there is great interest in improving network devices, such as optical amplifiers, which must cover a large bandwidth and generate greater gain than those currently available. For this reason in this work a computational simulation for a Quasi-system was carried out three energy levels of Erbium and Ytterbium varying their concentrations and proving that they are optimal candidates in a zinc phosphate matrix as this type of glass contains properties such as, high transparency, low melting point, high thermal stability, high gain density due to high solubility, low refractive index and low dispersion, which makes them optimal as signal amplifiers. The results confirm that by increasing the doping of the Erbium ion the gain of the amplifier decreases, contrary to the Ytterbium ion that by increasing the doping the gain of the amplifier increases.

Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths of Some Levels in Er i and Er ii

Abstract Radiative lifetimes for 104 levels of Erbium (Er) i in the energy range between 31,926.003 and 44,525.705 cm−1 and 51 levels of Er ii from 31,381.779 to 47,840.962 cm−1 were measured by a time-resolved laser-induced fluorescence method. Branching fraction (BF) determinations for 356 lines from 47 out of 104 Er i levels and 122 lines related to 19 out of 51 Er ii levels were completed based on the emission spectra of hollow cathode lamps recorded using the 1.0 m Fourier transform spectrometer and are available from the digital library of National Solar Observatory on Kitt Peak, USA (http://diglib.nso.edu/). By combining these BFs and the lifetime results measured in this work, absolute transition probabilities and oscillator strengths were determined for 352 lines of Er i and 92 lines of Er ii for the first time, increasing the total number of lines with experimental transition probabilities to over 910 for Er i and over 540 for Er ii.

Synthesis and visible-near-infrared photoluminescence emission of Er3+-doped LnP5O14 (Ln = La, Gd) ultraphosphates

Er3+-doped LnP5O14 (Ln = La, Gd) ultraphosphates were synthesized via solid state reaction. The phase purity and the structure of samples were characterized by the X-ray powder diffraction (XRD) and the Fourier transform infrared spectroscopy (FTIR). The optical properties were investigated by analysis of the photoluminescence emission spectra recorded in 430–900 nm and 1450–1600 nm wavelength range at room temperature. Upon visible excitation, the Ln1-xP5O14:xEr3+ (Ln = La, Gd; x = 1–5%) phosphors exhibit bright green emission bands, corresponding to transitions from the 2H11/2 and 4S3/2 erbium levels to the 4I15/2 ground state and week red luminescence related to the 4F9/2 → 4I15/2 transition. A strong luminescence at 1.53 nm in the infrared (IR) region due to 4I13/2 → 4I15/2 transition has been observed in Ln0.95P5O14:0.05Er3+ (Ln = La, Gd) phosphors under the excitation by 488 nm laser light. The experimental results suggest that Er3+ activated ultraphosphates hosts are useful for solid-state lasers applications.

Body burden of toxic metals and rare earth elements in non-smokers, cigarette smokers and electronic cigarette users

Smoking is considered an important source for inorganic elements, most of them toxic for human health. During the last years, there has been a significant increase in the use of e-cigarettes, although the role of them as source of inorganic elements has not been well established. A cross-sectional study including a total of 150 subjects from Brasov (Romania), divided into three groups (non-smokers, cigarette smokers and electronic cigarettes smokers) were recruited to disclose the role of smoking on the human exposure to inorganic elements. Concentration of 42 elements, including trace elements, elements in the ATSDR's priority pollutant list and rare earth elements (REE) were measured by ICP-MS in the blood serum of participants. Cigarette smokers showed the highest levels of copper, molybdenum, zinc, antimony, and strontium. Electronic cigarette (e-cigarette) users presented the highest concentrations of selenium, silver, and vanadium. Beryllium, europium and lanthanides were detected more frequently among e-cigarette users (20.6%, 23.5%, and 14.7%) than in cigarette smokers (1.7%, 19.0%, and 12.1%, respectively); and the number of detected REE was also higher among e-cigarette users (11.8% of them showed more than 10 different elements). Serum levels of cerium and erbium increased as the duration of the use of e-cigarettes was longer. We have found that smoking is mainly a source of heavy metals while the use of e-cigarettes is a potential source of REE. However, these elements were detected at low concentrations.

Optical temperature sensing of Er3+/Yb3+ doped LaGdO3 based on fluorescence intensity ratio and lifetime thermometry

The investigation of the fluorescence intensity ratio and the lifetime thermometry techniques for two rare earth perovskites-type oxide (LaGdO3:Er3+ and LaGdO3:Er3+/Yb3+) has been carried out. We have demonstrated that the intensity ratio of thermally coupled levels of erbium (2H11/2 and 4S3/2) is temperature dependant in the range from 283 to 393 K. The sensitivity parameter was found to reach a maximum value of 31 × 10−4 K−1 and 34 × 10−4 K−1 at 393 K and the temperature resolution to be equivalent to 1.61 and 3.1 K, for Er3+ and Er3+/Yb3+ doped oxide, respectively. By studying the temperature dependence of the normalized lifetimes in the range from 293 to 348 K, we proved that the sensitivity of the green emission (4S3/2) is higher than the red one (4F9/2) for both samples, and that it increases from 144 × 10−4 K−1 for LaGdO3:Er3+ to 179 × 10−4 K−1 for LaGdO3:Er3+/Yb3+. The thermal coefficients were quite large in comparison to those calculated for different luminescent materials and reported in literature. The repeatability of measurements was tested by performing heating and cooling cycles for both methods and the results show that these optical techniques have a good repeatability performance. Hence, the LaGdO3: Er3+, Yb3+ oxide has a precise and a satisfying sensitivity associated to a good thermal and chemical stability, suggesting that it can be a potential candidate in temperature sensing.

Enhanced down and upconversion emission for Li+ co-doped Gd2O3:Er3+ nanostructures

A phosphor with higher emission efficiency in the visible region can be very helpful in various optoelectronics applications such as solar cells. Effective conversion of UV and NIR radiations to more useful visible and red emissions were carried out through Gd2O3:Er3+ nanostructures synthesized by conventional co-precipitation method. The spectroscopic study of Gd2O3:Er3+ samples were carried out as a function of dopant concentration under the excitation wavelengths of 378, 975 and 1540 nm, respectively. The doping of erbium show downconversion emission at 561 and 660 nm under 378 nm excitation while upconversion emission under 975 and 1540 nm excitations shows upconversion of NIR photons to 561 and 660 nm visible emissions. The enhanced red emission (660 nm) at higher erbium concentration was observed due to the dominant cross-relaxation processes. The efficiency of upconversion luminescence is highly dependent on the various relaxation and energy transfer processes involved in different energy levels of erbium. The intensity of downconversion and upconversion emission was enhanced by lithium co-doping in Gd2O3:Er3+ nanostructures. The incorporation of alkali metal ions in Gd2O3:Er3+ shows considerable enhancement in downconversion and upconversion emission intensity making the phosphor more suitable for optoelectronic applications.

Upconversion emission of a novel glass ceramic containing Er3+, Yb3+:Sr1−xYxF2+x nano-crystals

Transparent oxyfluoride glass ceramics with a novel composition of Er3+, Yb3+:Sr1−xYxF2+x nano-crystals were processed. When excited under infrared light, an intense green upconverted luminescence was observed for the glass ceramic obtained from the precursor glass after a heat treatment of 4h at 750°C. X-ray diffraction and transmission electron microscopy analysis confirmed the precipitation of Sr1−xYxF2+x nano-crystals of sizes in the range of 9–45nm in the heat treated samples. The position of Er3+, Yb3+ ions in the sample (either amorphous or crystalline phases) was studied at four different heat treatment temperatures of 600, 650, 700 and 750°C. The measurements were based on analyzing the lifetimes of the 4S3/2 and 4I11/2 levels of erbium and the 2F5/2 level of ytterbium. Ytterbium and erbium ions started to incorporate into the crystalline phase when the heat treatment temperature was more than 650°C and 600°C, respectively. The sample that was heat treated at 750°C for four hours showed the highest green upconversion intensity among the other heat treated samples. In this sample, majority of Er3+, Yb3+ ions were in the crystalline phase as the lifetime of 4S3/2 (Er3+) and 2F 5/2 (Yb3+) levels were increased to 500μs and 2ms, respectively, which are longer than their values in the precursor glass. High ion solubility of Er3+ and Yb3+ in the novel Sr1−xYxF2+x nano-crystals and their local environments in the nano-structure are believed to be the reasons for this high intense green upconversion.

Influence of gallium on infrared luminescence in Er3+ doped Yb3Al5−yGayO12 films grown by the liquid phase epitaxy

Erbium (Er3+) doped ytterbium garnet Yb3Al5−yGayO12 (y=0, 0.55 and 1.1, YbAGG) thick films were grown by the isothermal liquid phase epitaxy method (LPE) on LuAG or YAG substrates. The influence of gallium on the photoluminescent properties of Er3+ is presented in this paper. Room temperature transmission and emission spectra were measured for the 0.5at% Er3+:YbAGG films with a different doping level of Ga. Also Er3+:Yb3Al3.9Ga1.1O12 (y=1.1) films with a different doping level of erbium (0.5, 1 and 2at%) were tested. The presence of gallium significantly affects the fine splitting and total intensity of erbium emission in an infrared region (the transition 4I13/2→4I15/2). Even at the highest doping level of erbium (2at%), no up-conversion luminescence was observed, resulting in a maximum efficiency of the infrared emission. The lifetime of luminescence at 1530nm was studied for all samples.

Optical spectroscopy and population behavior between ^4I_11/2 and ^4I_13/2 levels of erbium doped germanate glass

In this paper, mid-infrared emission properties and energy transfer mechanism were investigated in Er3+ doped germanate glass pumped by 980 nm diode laser. Spontaneous radiative transition probability and emission cross section at 2.7 μm were calculated to be as high as 36.45 s−1 and 1.61 × 10−20 cm2, respectively. Corresponding upconversion emission spectra and radiative lifetimes of 4I13/2 level were determined to elucidate the mid-infrared luminescent characteristics. Moreover, population behaviors of Er3+: 4I11/2 and 4I13/2 level were analyzed numerically via Inokuti-Hirayama model, rate equations and Dexter’s theory. In addition, DSC curves of developed samples were measured and thermal stabilities were studied to evaluate the ability of resisting thermal damage and crystallization. The results indicate that erbium activated germanate glass is a promising candidate for mid-infrared applications. This work may provide beneficial guide for investigation of population behaviors of Er3+ ions at 2.7 μm emissions.

Reduced erbium-doped ceria nanoparticles: one nano-host applicable for simultaneous optical down- and up-conversions.

This paper introduces a new synthesis procedure to form erbium-doped ceria nanoparticles (EDC NPs) that can act as an optical medium for both up-conversion and down-conversion in the same time. This synthesis process results qualitatively in a high concentration of Ce3+ ions required to obtain high fluorescence efficiency in the down-conversion process. Simultaneously, the synthesized nanoparticles contain the molecular energy levels of erbium that are required for up-conversion. Therefore, the synthesized EDC NPs can emit visible light when excited with either UV or IR photons. This opens new opportunities for applications where emission of light via both up- and down-conversions from a single nanomaterial is desired such as solar cells and bio-imaging.

Fluorophosphate nanostructured glass ceramics activated by erbium ions

Possibility of preparation of transparent nanostructured glass crystalline materials based on fluorophosphate glasses with high fluoride content is demonstrated. The influence of concentration of rare earth ions (REI) on the crystallization process is studied. We determined the conditions of heat treatment to form nanocrystals containing REI whose growth is evidenced by the results of X-ray phase analysis changes in the absorption and luminescence spectra and in the lifetime of the excited level of trivalent erbium.

A distributed model for continuous-wave erbium-doped fiber laser

A distributed model of a continuous-wave erbium-doped fiber laser is discussed. The model is based on two contra-propagated traveling laser waves, and includes inhomogeneous pumping, excited state absorption at the pump and the laser wavelengths, amplified spontaneous emission and radial distribution of populations of erbium levels. It is shown that excited state absorption is a main limiting factor to the laser's efficiency. Moreover, consideration of radial distributions of erbium levels' populations in the model reduces laser efficiency and decreases optimal reflection of the laser output coupler. The modeling results are in excellent agreement with the experimental study on the EDFL efficiency.

Er离子注入的富硅SiO2MOS-LED的可见和红外电致发光特性

Metal-oxide-semiconductor structure of ITO/Si-rich SiO2∶Er/Si containing erbium ions and silicon nanocrystals was fabricated by ion implantation of Si and Er combined with post-annealing.The electroluminescence spectra and current-voltage characteristics were measured to investigate the influence of silicon concentration on the excitation mechanism of luminescence centers and conductance process.It was found that the excitation mechanism of erbium ions was variational in the MOS-LED with silicon content.For the silicon concentration less than 5%,the upper levels of erbium can be excited by resonant energy transfer from silicon-oxygen deficiency centers,which induce an enhancement of the 522 nm peak emission intensity of Er3+ ion.For the silicon concentration above 5%,the excess silicon formed silicon nanocrystals by post-annealing.The direct tunneling of electrons between silicon nanocrystals dominate the conductance,resulting a decrease of average energy of hot electrons and quenching of all the electroluminescence peaks of erbium.

Radiative lifetimes of neutral erbium

Radiative lifetimes have been measured for 123 levels of neutral erbium using time-resolved laser-induced fluorescence on a slow beam of erbium atoms. Of the 123 levels, 56 are even parity and range in energy from 26 993 to 40 440 cm−1 and 67 are odd parity ranging from 16 070 to 38 401 cm−1. This set of Er i lifetimes is much more extensive than others published to date, with 90 of the 123 level lifetimes measured for the first time. These lifetimes will provide the absolute calibration for a large set of measured Er i transition probabilities. Spectroscopic studies of rare earth elements including erbium are motivated by research needs in both the astrophysics and lighting communities.

Infrared and visible emission of Er 3+ in combustion-synthesized CaAl 2O 4 phosphors

New near-infrared luminescent, monoclinic CaAl 2O 4:Er 3+ phosphor was prepared by using the combustion route at furnace temperatures as low as 500 °C in a few minutes. Combustion synthesized phosphor has been well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive analysis of X-ray (EDAX) mapping studies. The luminescence spectra of Er 3+-doped calcium aluminate were studied at UV (380 nm), vis (488 nm) and IR (980 nm) excitation. Upon UV and vis excitation, the CaAl 2O 4:Er 3+ phosphor exhibits emission bands at ~523 nm and at ~547 nm, corresponding to transitions from the 2H 11/2 and 4S 3/2 erbium levels to the 4I 15/2 ground state. A strong luminescence at 1.55 μm in the infrared (IR) region due to 4I 13/2→ 4I 15/2 transition has been observed in CaAl 2O 4:Er 3+ phosphor upon 980 nm CW pumping. In the spectrum of IR-excited up-conversion luminescence, green (~523 and ~547 nm) and red (662 nm) luminescence bands were present, the latter associated with the 4F 9/2→ 4I 15/2 transitions of Er 3+ ions. Both excited state absorption and energy transfer may be proposed as processes responsible for the population of the 4S 3/2 and 4F 9/2 erbium levels upon IR excitation. The mechanisms responsible for the up-conversion luminescence are discussed.