Near-infrared Emission Band Research Articles

Near-infrared to mid-infrared photoluminescence of Bi_2O_3-GeO_2 binary glasses

Near-infrared and mid-infrared (MIR) ultrabroad emission bands were observed in as-grown and annealed Bi(2)O(3)-GeO(2) binary glasses, in the wavelength ranges of 1000-1800 nm and 1800-3020 nm, respectively. The MIR emission band could appear through high doping ratio of Bi(2)O(3) or annealing process in air atmosphere. The structure of these glasses, the transformation of emission centers, and the effect of Al ions doping have been discussed, with the conclusion that the Bi(2)O(3)-GeO(2) binary glasses could be a promising laser material.

Direct radiative recombination in the Se-terminated nanoscale Si porous structure

We prepared vertical porous silicon nanowire (SiNW) arrays using the silver-assisted electroless etching method. The post-selenization treatment was carried out to passivate the surface of the nanostructure with Se-related bonds. Besides the great enhancement of the photoluminescence (PL) intensity and stability, the slow red emission band from the untreated porous SiNWs disappears and the new PL bands blue-shift to the higher energy, with the recombination rate more than three orders of magnitudes faster than that of the red emission band. The lifetime of 0.49 and 2.68ns are attributed to the recombination in the Si nanostructures passivated with SiSe, and SiSeO bonds, respectively. The fast recombination rates indicate that surface modification induced by selenization treatment could lead to the direct radiative recombination of Si nanostructure. Furthermore, a broad near-infrared emission band located at around ∼1300nm is also observed. These results are thought useful in the band gap engineering of Si.

Investigation of emission properties of Tm3+:Y2O3 transparent ceramic

A transparent and emitting ceramic of Y2O3 doped with 6% Tm3+ ions is fabricated by vacuum sintering with ZrO2. Absorption, photoluminescence (PL), and PL excitation (PLE) spectra are investigated in a spectral range of 200 to 2 100 nm at various temperatures between 296 and 12 K. Intense emission band appears at 450 to 465 nm in the visible range. Near-infrared emission bands are observed at 1 200 to 1 300 nm and 1 400 to 1 550 nm, with intense peaks at 1 270, 1 450, and 1 523 nm. The luminescence mechanisms and potential applications of the emissions are discussed with the help of Judd-Ofelt theory and PLE spectra.

Controlled oxidative synthesis of Bi nanoparticles and emission centers in bismuth glass nanocomposites for photonic application

Here we demonstrate an oxidative process to control metallic bismuth (Bi 0) nanoparticles (NPs) creation in bismuth glass nanocomposites by using K 2S 2O 8 as oxidant and enhanced transparency of bismuth glasses. Formation of Bi 0 NPs has been monitored by their distinct surface plasmon resonance (SPR) band at 460 nm in the UV–visible absorption spectra. It is further confirmed by the transmission electron microscopy (TEM) images which disclose the formation of spherical Bi 0 NPs whereas the selected area electron diffraction (SAED) pattern reveals their crystalline rhombohedral phase. These glasses are found to exhibit visible and near infrared (NIR) luminescence bands at 630 and 843 nm respectively on excitation at 460 nm of the SPR band. It is realized that the luminescence center of bismuth species is an uncertain issue, however, it is reasonable to consider that the emission band at 630 nm is due to the combination of 2D 5/2 → 4S 3/2 of Bi 0 and 2P 3/2 (1) → 2P 1/2 of Bi 2+ transitions, and that of NIR emission band at 843 nm is attributed to the 2D 3/2 → 4S 3/2 of Bi 0 transition.

Near-infrared emission bands of Er 3+-doped YAP and LSO crystals

The ground state absorption (GSA), photoluminescence (PL) and photoluminescence excitation (PLE) spectra for Er(1.0 at%):YAP and Er(0.5 at%):LSO were measured at room temperature. Based on the GSA spectra, the radiative transition rates and luminescence branch ratios of erbium ions were determined by the Judd–Ofelt (J–O) method. In the range of 1400–1700 nm Er(1.0 at%):YAP has intense absorption at 1509 nm (0.96×10 −20 cm 2), which is almost two times larger than the peak absorption of Er(0.5 at%):LSO. From the PL and PLE spectra, four intense emission bands around 850 nm ( 4S 3/2→ 4I 13/2), 980 nm ( 4I 11/2→ 4I 15/2), 1230 nm ( 4S 3/2→ 4I 11/2) and 1520 nm ( 4I 13/2→ 4I 15/2) were observed. The stimulated emission cross-sections of the four bands were calculated by the Fuchtbauer–Ladenberg (F–L) equation. The results suggest that Er(1.0 at%):YAP has potential to realize laser oscillation at 858 nm because of the relatively large simulated emission cross-section (1.76×10 −20 cm 2). The temperature dependences of the PL spectra for the two crystals were also investigated in the range of 290–12 K. The ∼1520 nm emission presents continuous increase with temperature, while the emissions around 850, 1230 and 980 nm firstly increase with temperature, then reach their own largest values at the transition temperatures (about 100 K), and finally decrease with temperature. These results were well interpreted by the temperature dependence of multi-phonon process.

Bismuth-sensitized efficient near-infrared luminescence from ytterbium in zeolites

Yb–Bi co-doped zeolites are prepared by a method consisting of a simple ion-exchange process and subsequent high-temperature annealing. We observe two strong near-infrared (NIR) emission bands overlapping in the range 930–1480 nm, corresponding to the electronic transitions of bismuth-related active centres (BiRAC) and Yb3+ ions, respectively. In the obtained products, the excitation wavelength of Yb3+ is extended to the range 420–850 nm, and the lifetime reaches 665 µs. In the zeolite matrix, Bi ions exist as BiRAC and Bi compound agglomerates. The former act as a sensitizer of Yb3+ ions, and the latter act as a blockage to seal the pores of zeolites, which enables Yb3+ ions to show efficient NIR emission even if the zeolites contain a large amount of coordinated water. The excellent optical and structural properties make these NIR-emitting nanoparticles promising in applications as biological probes.

Synthesis and structure of a series of new luminescent Ag–Ln coordination polymers and the influence of the introduction of an Ag(i) ion on NIR luminescence from the Ln(iii) centre

A series of new Ag–Ln coordination polymers [LnAg5(bdc)4]n (Ln = Eu (1); Yb (2); Er (3); Ho (4); H2bdc = 1,2-benzenedicarbolylic acid) has been synthesized by a hydrothermal method and characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, IR spectra, UV-Vis-NIR absorption spectra and fluorescence spectra. X-ray structural investigations reveal that these polymers are isomorphous and exhibit a 2D layer structure formed by a coordination bond and weak metal⋯metal interaction. Polymers 1–4 exhibit a characteristic emission corresponding to the Ln(III) ions in the near-infrared (NIR) region or in the visible region. Especially, the NIR emission bands of polymers 2–4 present evidently shift or splitting compared with the isolated Ln(III) ions due to formation of the Ag–Ln coordination polymer. In the Ag–Ln coordination polymer, the Ag⋯Ln separation is much shorter (3.71–3.75 Å), thus the d-orbital of the Ag(I) ion and f-orbital of the Ln(III) ion may interact and influence each other, which probably caused the inner levels of the Ag–Ln system to be tuned. This can have an important impact on the NIR emission band presenting shift or splitting, which can be confirmed by the UV-Vis-NIR absorption spectra. Solid 1 shows intense characteristic emissions of the Eu(III) ion in the visible region, which is attributed to sensitization from the ligands and Ag-block (Ag-ligand section).

Novel Three-Dimensional Pillared-Layer Ln(III)−Cu(I) Coordination Polymers Featuring Spindle-Shaped Heterometallic Building Units

The hydrothermal reaction of rare earth oxide, CuO, 2,6-pyridinedicarboxylic acid, and 4,4'-bipyridine in the presence of H(3)PO(3) resulted in the formation of a new series of 3d-4f heterometallic coordination polymers [Ln(pydc)(3)Cu(3)(bipy)(3).m(H(2)O)](n) (Ln = Pr (1), Nd (2), m = 5; Ln = Sm (3), Eu (4), Gd (5), Tb (6), Er (7), Yb (8), m = 4; pydc = 2,6-pyridinedicarboxylate anion; bipy = 4,4'-bipyridine). Complexes 1-8 are isostructural and structurally characterized by elemental analysis, FT-IR spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA), single-crystal X-ray diffraction, X-ray powder diffraction (XRPD), and nitrogen adsorption/desorption techniques. The synthesis results show that the addition of H(3)PO(3) in the reaction plays an important role in the formation of the compounds. Single-crystal X-ray diffraction analysis reveals that the heterometallic ions are first interconnected by mixing bridging ligands to produce a spindle-shaped heterometallic ring [Ln(6)(pydc)(6)Cu(12)(bipy)(6)], which is used as the second building unit (SBUs) and finally pillared by bridging bipy molecules to form the rare 3D pillared-layer porous Ln(III)-Cu(I) coordination polymers. Luminescence measurements made under excitation by UV rays reveal that Sm-Cu, Eu-Cu, and Tb-Cu compounds exhibit the characteristic emission bands of Sm(3+), Eu(3+), and Tb(3+) ions in the visible regions, respectively; near-infrared (NIR) emission bands from Nd(III) and Yb(III) ions can also be obtained in Nd-Cu and Yb-Cu compounds, respectively; while Pr-Cu, Gd-Cu, and Er-Cu compounds all display similar emission spectra of Cu(I) coordination compounds in the visible regions.

Aromatic Ring-Fused BODIPY-Based Conjugated Polymers Exhibiting Narrow Near-Infrared Emission Bands

Three conjugated copolymers, consisted of alternating p-phenylene-ethynylene and boron di(iso)indomethene units in the backbone, were synthesized via palladium-catalyzed Sonogashira coupling reaction of 1,4-diethynyl-2,5-dihexadecyloxybenzene and three diiodophenyl-fused BODIPY monomers. The structures and properties of the conjugated polymers were characterized by 1H NMR, 11B NMR, and Fourier transform infrared (FT-IR) spectroscopies, elemental analysis, size exclusion chromatography (SEC), UV−vis absorption spectroscopy, photoluminescence (PL) spectroscopy, and theoretical calculation using density-functional theory (DFT) method. The polymers obtained were fusible and soluble in common organic solvents including THF, benzene, toluene, CHCl3, and CH2Cl2, etc. The incorporation of the indomethene monomers into p-phenylene-ethynylene main chain led to red shifts in UV-absorption and PL spectra by extended π-conjugation of the copolymers in comparison with the monomers. Accordingly, the copolymers emitted i...

3-Hydroxypyridin-2-one complexes of near-infrared (NIR) emitting lanthanides: sensitization of holmium(III) and praseodymium(III) in aqueous solution.

Ho ho ho! Characteristic visible and near-infrared (NIR) emission bands of the PrIII and HoIII complexes of the tetradentate 1-methyl-3-hydroxypyridin-2-one chromophore are observed in aqueous solution. The HoIII complex has been structurally characterized and, for the first time for a HoIII complex, the kinetics of the luminescence decay in the NIR region have been determined in solution.

Spectral analysis of Er3+-, Er3+/Yb3+- and Er3+/Tm3+/Yb3+-doped TeO2–ZnO–WO3–TiO2–Na2O glasses

In this paper, we present the spectroscopic properties ofEr3+-,Er3+/Yb3+- andEr3+/Tm3+/Yb3+-dopednovel tellurite glasses. From the measured absorption spectra, Judd–Ofelt (JO) intensity parameters(Ω2,Ω4 andΩ6) have beenevaluated for the Er3+-doped glass. With 980 nm excitation three strong upconversionemission bands centered at 505, 520 and 630 nm were observed for bothEr3+- andEr3+/Yb3+-codoped glasses and the characteristic near-infrared emission bands were spectrally centered at1.535 µm. Thenear-infrared spectra of Er3+- and Er3+/Yb3+-doped glasses have shown full width at half-maxima (FWHM) around 100 nm and 120 nmfor the erbium transition, respectively. The measured maximum decay times of the transition (at wavelength1.535 µm) are about7.24 ms and 7.68 ms for 1.0Er3+ and 1.0Er3+/ 2Yb3+ (mol%)-codoped glasses, respectively. The maximum stimulated emission cross sectionsfor the transition of Er3+ and Er3+/Yb3+ are 8.64 × 10−21 and 6.78 × 10−21 cm2.From 1Er3+/ 1Tm3+/ 2Yb3+ (mol%)-codoped glass, broad near-infrared emission bands centered at 1510 nm () and 1637 nm () with full width at half-maxima (FWHM) around 52 nm and 60 nm, respectively, wereobserved. These glasses with broad near-infrared emissions should have potentialapplications in tunable lasers and broadband optical amplification at low-losstelecommunication windows

Sensitized electrophosphorescence of infrared emission diode based on copper phthalocyanine by an ytterbium complex

By inserting a layer of (dibenzoylmethanato)3-(bathophenanthroline)-ytterbium (Yb–C) between copper phthalocyanine (CuPc) emitting layer and electron transport layer, intense and broadband electroluminescence (EL) were achieved at 930–1300nm spectral region in a phosphorescent EL device. The intensity and bandwidth are increased by about 50 and 4 times, respectively, compared with the EL device without Yb–C layer. The improvement in the EL intensity and band broadening were attributed to the energy transfer from Yb–C to CuPc and the overlapping of the Yb3+ near-infrared emission band with the CuPc emission band.

Broadband near-infrared emission from Tm3+∕Er3+ co-doped nanostructured glass ceramics

Transparent SiO2-Al2O3-NaF-YF3 glass ceramics co-doped with Er3+ and Tm3+ were prepared by melt quenching and subsequent heating. X-ray diffraction and transmission electron microscopy experiments revealed that β-YF3 nanocrystals incorporated with Er3+ and Tm3+ were precipitated homogeneously among the oxide glass matrix. An integrated broad near-infrared emission band in the wavelength region of 1300−1700 nm, consisting of Tm3+ emissions around 1472 nm (H34→F34) and 1626 nm (F34→H36), and Er3+ emission around 1543 nm (I413∕2→I415∕2), was obtained under 792 nm laser excitation. The full width at half maximum of this integrated band increased with the increasing of [Tm]/[Er] ratio, and it reached as large as 175 nm for the 0.1 mol% Er3+ and 0.8 mol% Tm3+ co-doped sample. The energy transfers between Er3+ and Tm3+ were proposed to play an important role in tailoring the emission bandwidth of the sample.

Photoluminescence of Erbium-Doped Potassium Tantalate Niobate Polycrystalline

In this study, we investigated the luminescence properties of erbium-doped potassium tantalite niobate (KTaxNb1-xO3 or KTN) ceramics, which were prepared by the conventional solid-state reaction synthesis method. In this work, we studied the relationships of the crystal structure, and Raman and photoluminescence (PL) spectra with the tantalum concentration, respectively. The experiments showed that the tantalum dopants modified the intensity of the green, red and near-infrared emission bands. The experiments also showed a blue shift for the 2 mol % erbium doped KTN samples with different tantalum compositions. Doping Ta not only led to the change in PL intensity but also in spectral shapes. The PL spectra showed the splitting peaks for the samples with low Ta compositions. Then these peaks combined and broadened as Ta concentration increase. When Ta was substituted for Nb completely, the luminescence intensity of the green emission band had an increase of approximately about one order of magnitude, which was because of the absence of the first-order phonon relaxation in the high-Ta-concentration samples.

Purification, material synthesis, and infrared emission from Nd doped PbBr2 and PbI2

ABSTRACTWe report on the material synthesis and infrared optical properties of Nd doped lead bromide (PbBr2) and lead iodide (PbI2) bulk crystals. Commercial PbBr2 and PbI2 materials were purified through repeated solidification and horizontal zone refinement. After purification, Nd doped lead halides were synthesized and grown by Bridgman technique. Under optical excitation, Nd:PbBr2 samples exhibited several near-infrared emission bands centered at 816 nm, 891 nm, 963 nm, 1069 nm, 1183 nm, 1356 nm, and 1535 nm. The emission from Nd:PbI2 samples was similar to that of from Nd:PbBr2, but slightly shifted to longer wavelengths. The observation of 1540 nm emission from Nd3+ ions is unusual and reflects on the small non-radiative decay rates in the investigated halides. Lead halides have low maximum phonon energies, which reduces non-radiative decay due to multi-phonon relaxations. In contrast to Nd:YAG, Nd:PbBr2 and Nd:PbI2 exhibited efficient emission from the 4F5/2, 2H9/2 excited states, which are located only ∼1000cm−1 above the 4F3/2 level of Nd3+. Under 808 nm diode pumping, both samples also exhibited broad mid-infrared emission bands centered at ∼5.1 μm.

Upconversion fluorescence of Nd 3+ ions in K 2YF 5 single crystal

Upconversion fluorescence of Nd 3+ ions in K 2YF 5 single crystal was studied under 785-nm (near-infrared), 514.5-nm (green) and 325-nm (ultraviolet) laser excitation. With laser excitation set at 785 nm, a near-infrared upconversion emission band centered at 745 nm with a peculiar linear power dependence was observed and explained successfully by using a multiphonon assisted upconversion mechanism. With 514.5-nm laser excitation, five upconversion emission bands centered at 358, 386, 417, 451 and 496 nm were recorded. The power dependence of these emission bands was also studied and the upconversion mechanism was attributed to the excited state absorption from 4F 3/2 state. In addition, the ultraviolet upconversion fluorescence which peaked at 287 nm under 325-nm laser excitation was also presented and analyzed.

Observation of neodymium electroluminescence

Organic electroluminescence devices using a neodymium(III) complex as an emitting layer were fabricated. The cell structure of glass substrate/indium–tin–oxide/N,N′-diphenyl-N,N′-di(m-tolyl)-benzidine/tris(dibenzoylmethanato)(monobathophenanthroline)neodymium(III) complex/tris(8-quinolinolato)aluminum(III) complex/Mg:Ag was employed. Sharp near-infrared emission bands assigned to f–f transitions of neodymium ion were obtained at dc bias voltage of over 15 V.

Fine Structure Transitions of BiOH in the Near-Infrared Region

Near-infrared emission bands were observed near 6200 and 5700 cm−1when water vapor (H2O, D2O) was added to the reaction of bismuth vapor (Bix) with microwave-discharged oxygen in a fast-flow system. With the help ofab initiocalculations of Yang Khandoginet al.(to be published inJ. Mol. Spectrosc.) the bands were identified to be fine structure transitionsX̃2A″ →X̃1A′ andX̃3A′ →X̃1A′ between the components of the strongly split3A″ ground state of the as yet unknown bismuth hydroxide radical BiOH (BiOD).

Near-infrared emission bands of TeH and TeD

High-resolution emission spectra of TeH and TeD have been obtained in the region 4200 to 3600 cm −1 using a Bomem DA3.002 Fourier transform spectrometer. Analyses are given for the 0-0 and 1-1 bands of the X 2 2 Π 1 2 -X 1 2 Π 3 2 system of TeH and for the 0-0 band of TeD. In addition the 2-0 vibrational overtone bands of 130TeH, 128TeH, and 126TeH are observed and analyzed. Accurate molecular constants are given for the first time.

Electro- and photoluminescence from sintered ceramic-plate of ZnO:Zn phosphor

Electro- and photoluminescence from a sintered P-15 (ZnO:Zn) phosphor-ceramic-plate fabricated by an original technique is described. It was found that electroluminescence (EL) spectra consist of an ultraviolet, blue-green and near-infrared emission band. The EL spectra were also dependent on the resistance of the P-15 phosphor-ceramics used.