Near-infrared Emission Spectra Research Articles

Energy transfer of Er3+-Nd3+ co-doped in tellurite glass via energy level match

Er3+/Nd3+ co-doped tellurate glass was prepared by melt quenching method. The relationship between the energy levels of two rare earth ions was studied by absorption spectra and excitation spectra. At 379/407/488 nm excitation, visible light, near-infrared (NIR) emission spectra, and fluorescence attenuation curves were measured. The NIR emission spectrum and fluorescence lifetime show that Er3+ can transfer energy to Nd3+, thus enhancing the NIR emission of Nd3+ in tellurate glass. In the co-doped sample, under excitation of 379/407/488 nm, the NIR emission of Nd3+ has a concentration quenching point related to Er3+, and the optimal co-doped concentration is 1mol% ErF3. At 365/451 nm excitation, NIR emission was not enhanced and no energy transfer occurred. In contrast to the energy transfer between conventional Er3+-Nd3+ co-doped glasses, this paper investigates the effect of matching the higher Er3+ energy levels with adjacent Nd3+ levels on the energy transfer. The energy transfer process of Er3+-Nd3+ co-doped glasses is studied in the energy level diagram.

Luminescent Er3+ based single molecule magnets with fluorinated alkoxide or aryloxide ligands.

We report the synthesis, structures, and magnetic and luminescence properties of a series of new mono- and dinuclear Er3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4-tBu-2,6-(Ph2CH)2C6H2O]3Er(THF) (1), [(C6F5)3CO]3Er(Me3SiOH) (2), [(C6F5)3CO]3Er[(Me3Si)2NH] (3), [(C6F5)3CO]3Er(C6H5CH3) (4), [(C6F5)3CO]3Er(o-Me2NC6H4CH3) (5) and {[Ph(CF3)2CO]2Er(μ2-OC(CF3)2Ph)}2 (6). In compounds 1, 2, and 4, the Er3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er3+ is impacted by the presence of several relatively short Er⋯F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er3+ characteristic near infrared (NIR) emission associated with the 4I13/2 → 4I15/2 transition with a remarkably long lifetime going up to 73 μs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data.

Growth and near-infrared optical properties of Nd3+-doped KGd0.1Lu0.9(WO4)2 crystal

In this paper, x at.% Nd3+: KGd0.1Lu0.9-x(WO4)2 (x = 1, 2, 3, 4, 5) crystals were grown by the top seed solution growth method (TSSG). The crystal structure was analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), and the crystal structure data was obtained by Rietveld refinement. The absorption spectra, near-infrared emission spectra and fluorescence decay curves of Nd3+ ions in the crystal were measured at indoor temperature. According to Judd-Ofelt theory, the spectral intensity parameters Ω2, Ω4 and Ω6 are calculated. When the doping concentration is 3 at.%, Ω2 is the largest, which is 3.84 × 10−20 cm2, while the spectral mass factor is the lowest, which is 0.3734. The absorption and emission cross-section are calculated by combining the absorption spectrum and emission spectrum, and the maximum calculated result of emission cross-section is 1.35 × 10−19 cm2. The results show that Nd3+: KGd0.1Lu0.9(WO4)2 crystals has great application potential in the 1.0 µm field.

Anharmonic IR absorption spectra of the prototypical interstellar PAHs phenanthrene, pyrene, and pentacene in their neutral and cation states

Combination band and overtone transitions of polycyclic aromatic hydrocarbon (PAH) cations in the 2000–2900 cm-1 (5-3.5 µm) region are implicated as carriers of the ‘quasi-continuum’ observed in the near-infrared (IR) emission spectra of many astronomical objects. In neutral PAHs, the strongest absorption features are concentrated in the 700–900 cm-1 (14–11 µm) range, which are associated with CH out-of-plane bending motions. Upon ionization, this shifts to the 1000–1600 cm-1 (10–6 µm) range, where bands are associated with C=C stretches and CH in-plane bends. Anharmonicity is required to accurately characterize the IR absorption spectrum of PAHs, indicated herein by the ability to directly assign the bands in high-resolution experimental absorption spectra of neutral and cationic phenanthrene, pyrene, and pentacene. Neutral PAHs are indicated as the source of the strong 3.3 and 11.2 µm astronomical PAH features, while the broad features in the 6–10 µm region and the ‘quasi-continuum’ from 3.5–5 µm stem from PAH cations. This study reinforces the need for including anharmonicity in the computation of IR absorption and emission spectra of larger and more complex PAHs. This is particularly pertinent to the interpretation of data returned by JWST.

Visible upconverted and NIR luminescence properties of Er3+ and Er3+/Yb3+-doped Lu3Sc2Ga3O12 nanocrystals

Trivalent erbium and ytterbium embedded in Lu3Sc2Ga3O12 nanocrystals in the garnet phase were synthesised employing the citrate sol-gel method. The crystalline phase and size, grain size, and effect of ion concentration and laser pump power on the photoluminescence properties of lanthanide ions were systematically characterised. XRD results showed that the present phosphor was in the cubic garnet phase with an average crystallite size of 27 nm and a lattice constant of 12.325 Å. Morphology images revealed the particles to be nearly spherical and agglomerated. Partial energy level diagrams have been constructed using diffused reflectance and excitation spectra. Stokes and anti-Stokes photoluminescence spectra were observed under 980 nm laser excitation. The near-infrared (NIR) photons (980 nm) were successfully converted into visible radiation. Upconverted luminescence spectra consisted of two strong peaks located in the green and red regions, corresponding to the 2H11/2,4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of the Er3+ ion. The intensity ratio of red to green emission bands increased with increasing Er3+ or Yb3+ concentrations as well as with the pump power of laser. Power-dependent photoluminescence spectra revealed that there were two photons involved in the upconversion mechanism. The decay profiles of the thermally coupled 2H11/2,4S3/2 levels of Er3+ showed a non-exponential nature accompanied by a shortening of lifetime as the concentration increased. CIE colour co-ordinates were located in the green region and shifted to the yellow region with increasing Yb3+ ion concentration. NIR emission spectra exhibited an intense peak at around 1535 nm, attributed to the 4I13/2 → 4I15/2 transition of Er3+ ion, the intensity of which was observed to increase with the incorporation of Yb3+ ions up to 5 mol%, confirming the existence of Yb3+-to-Er3+ energy transfer processes. Therefore, the present phosphors can be used for photovoltaic cells, solid-state light emitting diodes, and display devices.

Optical transition and near-infrared upconversion luminescence properties of YNbO4: Er3+, Yb3+ phosphors

Optical transition and near-infrared upconversion luminescence properties of Er3+ single-doped and Er3+, Yb3+ co-doped YNbO4 phosphors are reported. Based on the framework of Judd-Ofelt theory and modified Judd-Ofelt calculation method, the optical transition properties of Er3+ and Yb3+ ions in YNbO4: Er3+, Yb3+ sample were studied, respectively. The calculated results showed that the absorption cross-section of Er3+ ion at ∼1550 nm is larger than that at ∼980 nm in YNbO4: Er3+ phosphor. And, the absorption cross-section of 2F7/2 → 2F5/2 transition of Yb3+ in YNbO4: 15.0 mol% Er3+, 15.0 mol% Yb3+ sample was calculated to be 138.70 × 10−20 cm2. According to the emission cross section of Er3+ (4I11/2 → 4I15/2) and the absorption cross section of Yb3+ (2F7/2 → 2F5/2), the energy transfer rates from Er3+ to Yb3+ were quantitatively analyzed via the Föster-Dexter model. Furthermore, 1550 nm was selected as the excitation wavelength, the near-infrared upconversion emission spectra of YNbO4: Er3+, Yb3+ samples were measured. It was found that the sample has strong emission at ∼980 nm and the emission intensity was still enhanced with the incorporation of Yb3+.

Influences of Mn2+ ions, and Mn2+–Yb3+ dimer on the optical band gaps and bandwidth flatness of near-infrared emissions of Ho3+/Tm3+, Ho3+/Tm3+/Yb3+ co-doped calcium aluminosilicate glasses

We investigate and report the influences of Mn2+−Yb3+ dimer on the optical band gaps and bandwidth flatness of near-infrared (NIR) emission spectra of Ho3+/Tm3+, and Ho3+/Tm3+/Yb3+ co-doped CaO–Al2O3–SiO2 (CAS) calcium aluminosilicate glasses. Differential thermal analysis (DTA) and Energy dispersive X-ray spectroscopy (EDS) analyzes were performed to determine temperature values for heat treatment and elemental composition existing in the glass materials, respectively. NIR emission spectra of Ho3+/Tm3+/Yb3+ co-doped CAS glasses with a bandwidth of ∼450 nm using a 980 nm laser diode (LD) as the excitation resource was identified. Influences of Mn2+ ions and Mn2+–Yb3+ dimer on the direct/indirect optical band gaps, and bandwidth flatness of NIR emission of Ho3+/Tm3+/Yb3+ co-doped were investigated. At the same time, we determined the optimal Mn2+:Yb3+concentration ratio for the best flatness of the bandwidth NIR emission of Ho3+/Tm3+/Yb3+ co-doped CAS glasses.

A strong H− opacity signal in the near-infrared emission spectrum of the ultra-hot Jupiter KELT-9b

We present the analysis of a spectroscopic secondary eclipse of the hottest transiting exoplanet detected to date, KELT-9b, obtained with the Wide Field Camera 3 aboard the Hubble Space Telescope. We complement these data with literature information on stellar pulsations and Spitzer/Infrared Array Camera and Transiting Exoplanet Survey Satellite eclipse depths of this target to obtain a broadband thermal emission spectrum. Our extracted spectrum exhibits a clear turnoff at 1.4 μm. This points to H− bound-free opacities shaping the spectrum. To interpret the spectrum, we perform grid retrievals of self-consistent 1D equilibrium chemistry forward models, varying the composition and energy budget. The model with solar metallicity and C/O ratio provides a poor fit because the H− signal is stronger than expected, requiring an excess of electrons. This pushes our retrievals toward high atmospheric metallicities ([M/H] = 1.98−0.21+0.19) and a C/O ratio that is subsolar by 2.4σ. We question the viability of forming such a high-metallicity planet, and therefore provide other scenarios to increase the electron density in this atmosphere. We also look at an alternative model in which we quench TiO and VO. This fit results in an atmosphere with a slightly subsolar metallicity and subsolar C/O ratio ([M/H] = −0.22−0.13+0.17, log (C/O) = −0.34−0.34+0.19). However, the required TiO abundances are disputed by recent high-resolution measurements of the same planet.

Optimizing Broadband Near-Infrared Emission in Bi/Sn-Doped Aluminosilicate Glass by Modulating Glass Composition.

The Bi/Sn-doped aluminosilicate glass samples were prepared using a melting–quenching method and their near-infrared (NIR) emission properties were studied. An ultra-broadband NIR emission ranging from 950 nm to 1600 nm was observed in all samples under 480 nm excitation, which covered the whole fiber low-loss window. The NIR emission spectrum showed that the maximum emission peak was about 1206 nm and the full width at half maximum (FWHM) was about 220 nm. Furthermore, the NIR emission intensity strongly depends on the composition of the glass, which can be optimized by modulating the glass composition. The Bi0 and Bi+ ions were the NIR luminescence source of the glass samples in this paper. The Bi/Sn-doped aluminosilicate glass has the potential to become a new type of core fiber material and to be applied to optical fiber amplifiers (OFAs), based on its excellent performance in ultra-broadband NIR emission.

Structural and optical properties in Tm3+/Tm3+–Yb3+ doped NaLuF4 glass‐ceramics

AbstractTransparent NaLuF4 glass‐ceramics (GCs) doped with Tm3+ and Tm3+/Yb3+ have been prepared by melting‐quenching followed by thermal treatment at temperatures near the glass transition temperature. The crystallization process has been studied using X‐ray diffraction (XRD) and high‐resolution transmission electron microscopy (HRTEM). NaLuF4 nanocrystals (NCs) ranging 9–30 nm in size are the only crystalline phase, the crystal size increasing with the dopant concentration. Energy dispersive X‐ray (EDX) measurements confirm the Tm3+ and Yb3+ incorporation in the NCs. Optical characterization included the analysis of up‐conversion (UC) as well as the Near‐infrared (NIR) luminescence. NIR emission spectra of Tm3+ and Yb3+ in co‐doped samples confirmed an efficient energy transfer between both ions. No UC emissions are observed in Tm3+ single‐doped glass and GCs. Yb3+ incorporation favors the Tm3+‐Tm3+ UC processes resulting in Tm3+ blue, yellowish‐red and NIR UC emissions after excitation at 975 nm. Blue UC emission is also observed in the codoped samples after Tm3+ excitation at 791 nm. These effects were more evident for the GCs compared to the base glasses, confirming the RE ions incorporation in the NCs. As a result, these GCs can be used to tune the UC emission from NIR to blue by selective excitation.

Investigations on the luminescence and gamma ray shielding features of Pr3+: BLCZFB glass for orange-red laser and radiation applications

Praseodymium (Pr3+) ions doped barium lithium calcium zinc fluoroborate (BLCZFB) glasses were prepared with the melt quenching technique, and their physical, optical, and shielding properties were estimated. Their amorphous nature was verified with X-ray diffraction (XRD) pattern. Each of their absorption spectra exhibited nine peaks in the visible and near infra-red (NIR) regions. The absorption bands of oscillator strength and Judd-Ofelt (J-O) parameters were used to evaluate their radiative parameters. Their predominant emission peak in their visible emission spectra was observed at 604 nm (16556 cm−1), attributed to 1D2→3H4 transition. And their main emission peak in the NIR emission spectra was at the wavelength of 1458 nm (6858 cm−1), corresponding to the 1D2→1G4 transition. Their spectroscopic properties, including the stimulated emission cross-section (σPE), branching ratio (βR), quantum efficiency (η), gain bandwidth (σPE×Δλeff), and optical gain parameter (σPE×τexp) were also calculated for the visible (1D2→3H4) and NIR (1D2→1G4) emission transitions. From their emission spectra, the color chromaticity coordinates, (x, y) and (u, v), the color purity (CP), and the correlated color temperature (CCT) were calculated. The concentration quenching mechanism and energy transfer process were also explored from the emission spectra. Both the visible and the NIR lifetime curves exhibited non-exponential behaviour for all the glasses. The experimental lifetime decreases with the increase of Pr3+ ions concentration, which could be attributed to the cross-relaxation channels. The decay profiles are well fitted with Inokuti-Hirayama (IH) model (S = 6) to realize the energy transfer process. The energy transfer parameter (Q), donor-acceptor interaction parameter (CDA), and critical distance (R0) were also calculated. Next, the direct and indirect allowed transitions, the band tailing (B), and Urbach parameters (ΔE) were calculated. Then the shielding parameters, including the mass attenuation coefficient (MAC), the mean free path (MFP), and the equivalent atomic number (Zeq), etc., were articulated. Based on the above parameters, 1PrBLCZFB and 2PrBLCZFB glasses are suggested to be used for future solid-state orange-red laser, photonic devices, optical amplifier, and gamma ray shielding.

First Detection of Hydroxyl Radical Emission from an Exoplanet Atmosphere: High-dispersion Characterization of WASP-33b Using Subaru/IRD

Abstract We report the first detection of a hydroxyl radical (OH) emission signature in the planetary atmosphere outside the solar system, in this case, in the dayside of WASP-33b. We analyze high-resolution near-infrared emission spectra of WASP-33b taken using the InfraRed Doppler spectrograph on the 8.2 m Subaru telescope. The telluric and stellar lines are removed using a detrending algorithm, SysRem. The residuals are then cross-correlated with OH and H2O planetary spectrum templates produced using several different line lists. We check and confirm the accuracy of OH line lists by cross-correlating with the spectrum of GJ 436. As a result, we detect the emission signature of OH at K p of km s−1 and v sys of −0.3 km s−1 with a signal-to-noise ratio (S/N) of 5.4 and a significance of 5.5σ. Additionally, we marginally detect H2O emission in the H-band with an S/N of 4.0 and a significance of 5.2σ using the POKAZATEL line list. However, no significant signal is detected using the HITEMP 2010, which might be due to differences in line positions and strengths, as well as the incompleteness of the line lists. Nonetheless, this marginal detection is consistent with the prediction that H2O is mostly thermally dissociated in the upper atmosphere of the ultra-hot Jupiters. Therefore, along with CO, OH is expected to be one of the most abundant O-bearing molecules in the dayside atmosphere of ultra-hot Jupiters and should be considered when studying their atmospheres.

Non-Linear Optical Properties of Er3+-Yb3+-Doped NaGdF4 Nanostructured Glass-Ceramics.

Transparent oxyfluoride glass–ceramics containing NaGdF4 nanocrystals were prepared by melt-quenching and doped with Er3+ (0.5 mol%) and different amounts of Yb3+ (0–2 mol%). The selected dopant concentration the crystallization thermal treatments were chosen to obtain the most efficient visible up-conversion emissions, together with near infrared emissions. The crystal size increased with dopant content and treatment time. NaGdF4 NCs with a size ranging 9–30 nm were obtained after heat treatments at Tg + 20–80 °C as confirmed by X-ray diffraction and high-resolution transmission electron microscopy. Energy dispersive X-ray analysis shows the incorporation of rare earth ions into the NaGdF4 nanocrystals. Near-infrared emission spectra, together with the up-conversion emissions were measured. The optical characterization of the glass–ceramics clearly shows that Er3+ and Yb3+ ions are incorporated in the crystalline phase. Moreover, visible up-conversion emissions could be tuned by controlling the nanocrystals size through appropriated heat treatment, making possible a correlation between structural and optical properties.

Precipitation of rare-earth ions doped pyrochlore nanocrystals in glasses

Pyrochlore structured nanocrystals could have large solubility of rare-earth ions, making them promising for application in various light emitting materials and immobilization of radioactive nuclear waste. In this work, rare-earth doped pyrochlore structured nanocrystals were precipitated in glasses using melt-quenching and subsequent thermal treatment. Lu3+ along with Yb3+ and Er3+ ions were doped into the glasses, and Yb3+ and Er3+ were employed as probes to illustrate the incorporation of rare-earth ions into pyrochlore nanocrystals. X-ray diffraction patterns and transmission electron microscopy showed the precipitation of pyrochlore nanocrystals with average diameters of 13–15 nm upon thermal treatment. Energy dispersive spectroscopy, absorption spectra, visible and near-infrared emission spectra all confirmed the incorporation of rare-earth ions into these pyrochlore structured nanocrystals.

Theoretical calculations and experimental investigations of lead phosphate glasses singly doped with Pr3+ and Tm3+ ions using luminescence spectroscopy

Abstract Lead phosphate glasses singly-doped with selected Ln3+ ions (Ln = Pr, Tm) were prepared by traditional melt-quenching method. The effect of concentration of optical active dopants in glass composition on spectroscopic properties of lead phosphate glasses were systematically investigated based on excitation, visible and near-infrared emission spectra as well as luminescence decay analysis. It was found that the luminescence intensity decreases with increasing content of Pr3+ and Tm3+ ions due to the concentration quenching. Also, the luminescence lifetimes of 1D2, 1G4 (Pr3+) and 1D2, 3H4 (Tm3+) states decrease with increasing concentration of both ions. Based on luminescence decay analysis and calculations using theoretical Inokuti-Hirayama model it was confirmed that non-radiative processes like cross-relaxation among the donor systems are dominate and influence direct donor-acceptor energy transfer in lead phosphate glasses. Moreover, the obtained results suggest clearly lower self-quenching emission in lead phosphate glasses doped with Pr3+ than Tm3+ ions.

Influence of optimized concentration of samarium (III) ions on structural, optical and fluorescence properties of calcium-based lead borate glasses for reddish-orange device applications

The calcium-based lead borate glasses doped with 1 mol% Sm3+ ions were prepared using melt quenching technique. The prepared glass samples were analyzed through an X-ray diffractometer, FT-IR, Optical absorption, Emission, and fluorescence decay analysis. Physical properties have been calculated for the prepared glasses. The absorption spectrum has been recorded for 1.0 mol% Sm3+ ions doped calcium-based lead borate glasses. From the absorption spectrum, oscillatory strengths and JO intensity parameters have been calculated. The visible and near-infrared emission spectra were recorded with 402 nm excitation for 1.0 mol% Sm3+ ions. The prepared glass shows that the highest emission intensity for 4G5/2 → 6H11/2 transition centered at 610 nm. Emission properties for the prepared glass were calculated. Decay profile has been analyzed and lifetime value for 4G5/2 exited level of Sm3+ ion calculated for 1.0 mol% Sm3+ ions doped Ca-based lead borate glass: decay profile was well fitted for exponential decay 2, and the lifetime of 4G5/2 excited level is 1.041 ms. The obtained results suggested that the present 1.0 mol% Sm3+ ions doped calcium-based lead borate glass could be useful for the visible lasers and or photonic display devices applications.

Thermal, structural, mechanical and 1.8 μm luminescence properties of the thulium doped Pb-K-Al-Na glasses for optical fiber amplifiers

ABSTRACT Lead based phosphate glasses with the concentration variation of Tm3+ ions (PPbKANTm) were prepared by using melt-cast technique. These glasses are characterized by using thermal (DSC), structural (XRD and Raman), mechanical (Knoop hardness) and optical (absorption, emission and lifetime) studies. The structural geometry of the PPbKAN glasses were explored by Raman spectrum and the phonon energy was found to be 1124 cm−1. The three Judd-Ofelt parameters were obtained in order to attain information about the ligand environment, radiative lifetime as well as branching ratios of Tm3+ ion. In general, McCumber theory found to be quite successful to evaluate the cross-section of the metastable state, 3F4→3H6 (1.8 μm). Distinctive down-conversion (420–500 nm) was studied by exciting the 1G4(Tm3+) state. The decay rate of 1D2→3F4 level measured for all the concentrations under λexc = 355 nm. With λexc = 808 nm, the near-infrared emission spectra was also studied and the spectra having two emission transitions of 3H4→3F4 at 1.47 μm and 3F4→3H6 around 1.8 μm. The emission intensity increases with increasing Tm3+ ions concentration upto 1.0 mol% and decreases beyond 1.0 mol% where the optimal 1.8 μm emission is observed when Tm3+ ions concentration is 1.0 mol%. From the near-infrared emission spectra, the crucial spectroscopic parameters such as emission (1.41 × 10−20 cm2) cross-section, effective bandwidth (197 nm) and gain coefficient (277.7 × 10−27 cm3) were evaluated. The Knoop hardness was measured for all the glasses and confirms that the present lead based phosphate glasses doped with Tm3+ ions are mechanically stable. From the analysis of the outcome, it was concluded that the present PPbKANTm glasses are useful for broad band amplifications.

Synthesis and Luminescence properties of Lithium Aluminium Phosphate Glasses Doped with Nd3+ Ion for Laser Medium

Nd3+ ion doped lithium aluminium phosphate glasses were synthesized and studied their properties for laser medium application. The density and the refractive index of the glass samples were carried out at the room temperature. The optical and luminescence properties were studied by investigating absorption and NIR emission spectra of the glass samples. The glasses absorbed photons in ultraviolet (UV), visible light (VIS) and near-infrared (NIR) regions are clearly observed from absorption spectra. For the photoluminescence properties, the glass samples showed the strongest emission at 1063 nm when it were excited by 581 nm which assigned to the energy transitions of Nd3+. The three phenomenological Judd-Ofelt parameters (Ω2, Ω4, Ω6) were determined from the spectral intensities of absorption band in order to calculate the radiative transition possibility (AR), stimulated emission cross section (σ(λp)) and branching ratio (βR) of the w4F3/2 → 4I9/2, 4I11/2 and 4I13/2 transitions. From the obtained results the conclusions made about the possibility of using these glasses as laser material.

Broad Emission and Absorption Line Outflows in the Quasar SDSS J163345.22+512748.4

Abstract We present a detailed study of the optical and near-infrared (NIR) emission and absorption line spectrum of the quasar SDSS J163345.22+512748.4. We discovered on the newly acquired NIR spectrum a highly metastable neutral helium broad absorption line (BAL) He i* λ10830 with a width of ∼2000 km s−1 and a blueshift of ∼7000 km s−1 in the velocity space. The BAL system is also significantly detected in Mg ii and He i* λ3889. We estimate a column density of (5.0 ± 1.7) × 1014 cm−2 for the He i*(2 3S) level and infer an ionization parameter of U A = 10−1.9±0.2 for the BAL outflow, assuming that the BAL region is thick enough for a full development of an ionization front. The total column density of the BAL outflow is constrained in the range N H ∼ 1021–1021.4 cm−2. We also found that the bulk of both Mg ii and UV Fe ii, as well as of Hα broad emission lines (BELs), are blueshifted with a velocity of ∼2200 km s−1 with respect to the quasar systemic redshift. We constrain the blueshifted BEL region to have a covering factor C f ≈ 16%, density n H ∼ 1010.6–1011.3 cm−3, column density N H ≳ 1023 cm−2, and ionization parameter U E ∼ 10−2.1–10−1.5. The outflow gas is located at ∼0.1 pc away from the central ionization source, at a scale comparable to the broad-line region. A toy kinetic model has been proposed to reproduce the profile of Mg ii BEL well if a partial obscured axisymmetric geometry of the outflow with a radial velocity as observed from the BALs is assumed.

Enhanced 2.0 µm emission in Nd3+/Yb3+/Ho3+ tri-doped tellurite glass: Role of Yb3+ as a bridge

In this paper, Nd3+/Yb3+/Ho3+ tri-doped scheme was developed and the enhanced 2.0 µm band emission of Ho3+ by introducing the third Yb3+ into Nd3+/Ho3+ co-doped tellurite glass was obtained. Under the excitation of 808 nm laser diode (LD), the near-infrared emission spectrum displayed that the 2.0 µm band peak intensity was increased by about 2.4 times when introducing 1 mol% amount of Yb2O3, which is attributed to the newly established energy transfer channel of Nd3+ → Yb3+ → Ho3+. The decrease of Nd3+:4F3/2 level lifetime and increase of Ho3+:5I7 level lifetime evaluated from the fluorescence decay curves demonstrated the observed luminescent phenomenon. The mechanism analysis about energy transfer together with micro-coefficient calculation were carried out to understand the role of Yb3+ as a bridge and phonon assistance in the accomplishment of energy transfers among Nd3+, Yb3+ and Ho3+. Meanwhile, the 2.0 µm band spectroscopic property of Ho3+, the structural information and thermal stability of tellurite glass were investigated by application of Judd-Ofelt theory, and measurements of XRD pattern and DSC curve respectively. The obtained results indicate that Nd3+/Yb3+/Ho3+ tri-doped tellurite glass with good thermal stability is a promising candidate material in improving 2.0 µm band emission performance of Ho3+.