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In this work, we report the preparation of monolayer silica@gold core-shell nanoparticle (SiO2@Au NP) nanostructures, which combines spin-coating, nanoscale masking and in situ reduction methods. Using this approach, a potential SERS substrate based on a composite particles of SiO2@Au NP monolayer array was fabricated. The surface morphology and optical properties of the samples were performed by scanning electron microscopy (SEM) and ultraviolet-visible (UV–vis) spectrophotometry. To study the SERS properties of the substrate, crystal violet (CV) was selected as the probe molecule. The Raman activity of characteristic vibrational bands of CV showed better when the excitation wavelength was close to the plasma peak of the SiO2@Au NPs. In addition, the Raman signal of the probe molecule on the SERS substrate presented good homogeneity, reproducibility and stability, also reproduce the SERS spectra after three weeks. Furthermore, the Raman enhancement factor (1.4×107), the detection limit (1×10−8 mol/L) and the relative standard deviation (RSD, 14.07 %) were evaluated. Our approach has potential advantage in the fabrication of viable solid SERS substrates that provides a possibility for commercialization used in nondestructive testing, food testing and detection of low-concentration.

Gold (Au) nanocap arrays and hollow gold nanocap particles were prepared by dip-coating technique combined with wet chemical reduction method, and followed by sonication and dissolution of the silica colloidal template. The surface morphologies and optical properties of the obtained samples were characterized by scanning electron microscopy, transmission electron microscope, and ultraviolet-visible spectrophotometer, respectively. Gold nanocap arrays and hollow gold nanocap particles were used as substrates to detect the surface-enhanced Raman scattering spectra of malachite green and methylene blue (MB), respectively. It was found that the gold nanocap arrays had higher enhancement ability than hollow gold nanocap particles, with enhancement factor of 1.3 × 105 and 3.5 × 103, respectively. In addition, gold nanocap arrays exhibited excellent reproducibility with a relative standard deviation of less than 5% and about 10% across a single substrate and between different substrates, respectively. Th...

Anisotropic metal nanoparticles are of considerable interest to researchers because of their unique optical, electronic and catalytic properties compared with spherical nanoparticles. This Letter describes how chloride ions and citrate ions can be added to silver (Ag) nitrate solution to synthesise anisotropic silver nanostructures especially to form the Ag nanowires (AgNWs) without high hydrothermal or solvothermal operating temperatures. The AgCl colloidal precipitates were produced in the initial stage promoting the reduction of free silver ions and helping control silver ions at low concentration for the growth of AgNWs. The synthesis of AgNWs was also temperature and hydroxide radical dependent since the citrate ions could direct the growth of AgNWs at proper temperatures (over 130°C) in the absence of chloride ions. Transmission electron microscopy and UV–vis absorption spectra have been used to investigate the obtained products. The experimental results suggested that the chloride ions played a crucial role in directing the growth of anisotropic Ag nanostructures.

In this paper, silica nanoparticles (SiO2) were modified by using esterification and a large-area monolayer of SiO2 nanoparticles was fabricated by using the Langmuir–Blodgett (LB) assembly technique. Then, a layer of gold nanoshell was sprayed at this monolayer film to obtain a large-area SiO2/Au core–shell nanostructure for surface-enhanced Raman scattering (SERS). The synthesized SiO2 were characterized by transmission electron microscopy (TEM). The different surface pressures were studied to prepare an ordered close-packed silica monolayer. And the prepared SiO2 nanoparticle monolayer substrates were examined by scanning electron microscopy (SEM). Crystal violet (CV) and methylene blue (MB) were used as Raman scattering probe molecules to study the enhancement performance of the substrates. The characteristic vibrational bands of CV and MB were observed and assigned on the esterifiable silica nanoparticles substrates. The average Raman enhancement factors were discussed and the maximum was reached to 106. This experiment demonstrated that the large-area SERS substrates have an important application potential in the analytical measurement field.

The effects of adding catalyst to the K2CO3 solution used for texturing crystalline silicon have been studied. The pyramid structure is rectangular pyramid model, which can produce a good effect of point. The parameters of the etching process such as temperature and etching time were examined to study the effects on shape and geometry of the microstructure which is the subject of hot research in the preparation of Raman substrate. Textured surfaces with the small pyramid structure, good surface coverage and uniformly distributed pyramids are that we want to get the ideal surface texture. The intensity of the Raman spectra based on the pyramidal shape models. For Raman detection technology provides the foundation and conditions.

SiO2–Au core-cap nanostructure arrays were prepared by dip-coating technique combined with wet chemical reduction method. The surface morphologies, structures, and optical properties of the obtained samples were characterized by scanning electron microscopy, X-ray diffraction, and ultraviolet–visible spectrophotometer, respectively. The surface-enhanced Raman scattering (SERS) activity of SiO2–Au core-cap nanostructure arrays substrates was investigated using leucine as probe molecule. And the relationship between the SERS effect and the surface plasmon resonance (SPR) peaks was discussed. High-quality, stable, and reproducible SERS spectra of leucine were successfully obtained. When the maximum SPR peak matched with the excitation wavelength, the substrate gave rise to the highest SERS enhancement. Furthermore, six different fluorescent dyes were also chosen as probe molecules. It was found that the substrate showed good Raman enhancement and highly efficient fluorescence quenching characteristic on these fluorescent dyes.

A large-area efficient surface enhanced Raman scattering (SERS) substrate was deposited by Langmuir–Blodgett (LB) assembly and followed by sputter coating process. The interparticle distance of silica nanospheres was convenient and readily regulated by controlling the surface pressure. After sputter coating with a small amount of gold, the nanocomposite film was formed. The surfaces of nanostructures were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The applicability of the nanostructures as SERS substrates was investigated by adsorption of crystal violet (CV) molecules. Different SERS effects were observed on deposited gold nanostructure upon large-area silica nanospheres monolayer with diameter of 250, 570 and 800 nm. It was also discussed the nanospheres with diameter of 250 nm for the fabrication of ordered arrangement of monolayers at surface pressures of 10–30 mN/m. These substrates with the close-packed nanospheres and sputtering of gold were found to exhibit high and uniform enhancement of the Raman signal across the entire surface. The averaged surface enhancement factor (ASEF) was calculated and discussed. The fabricated nanocomposite structures could be utilized as low-cost SERS-active substrates for biomedical and analytical chemistry field.

Colloidal silver nanoparticles were prepared by a simple chemical reduction method. The effect of L-cysteine on the surface-enhanced Raman scattering activity of colloidal silver nanoparticles was investigated by using malachite green as a probe molecule. It was found that the surface-enhanced Raman scattering activity of colloidal silver nanoparticles was improved tremendously with the help of L-cysteine. The possible reasons for this enhancement effect were given. Specifically, in silver colloidal solution, no surface-enhanced Raman scattering spectrum of malachite green was observed at a relatively low concentration (≤2.5 × 10−5 mol/L). However, well-resolved and high-quality surface-enhanced Raman scattering spectra of malachite green were successfully obtained after the addition of L-cysteine to silver colloids, and the minimum detection limit for malachite green was down to 10−8 mol/L.

InAs/GaSb superlattice in infrared detector was grown on GaSb substrates by molecular beam epitaxy technique. Using inductively coupled plasma (ICP) etching technique and Cl2/Ar etching gas, the smooth mesa of the device was formed. The influence of etching time, Cl2 percent and RF power on the etching rate and the surface morphology of InAs bulk, GaSb bulk materials and superlattice were studied. It showed that the etching rate of InAs was lower than that of GaSb and the etching surface was smooth at Cl2 in the range of 20%~40%. The results will benefit to forming ohm contact and decrease surface leakage current in the photovoltaic detector.

The energy band structure of InAs/GaSb superlattice can be tailored by changing the thickness of InAs or GaSb layer thickness. Different superlattice as InAs/GaSb (4ML/8ML, 8ML/8ML and 16ML/7ML) for cut-off wavelengths from short to long IR wavelength were designed and deposited on GaSb substrates by melocular beam epitaxy system. The lattice mismatch was below 1000ppm under the careful Ga1-xInx- type interface control. The responsitivity revealed the band structure in InAs/GaSb superlattice can be tailored and the cutoff wavelength was from 2.5μm to 11μm. The current-voltage relation and the differential resistance in infrared photodiode were also measured and studied.

Lead zirconium titanate Pb (Zr0.52Ti0.48)O3(PZT) thin films have been deposited on Pt/Ti/Si substrate by rf-magnetron sputtering. X rays diffraction revealed that at 600°C the PZT thin film had crystallized into ABO3perovskite phase. Degree of crystallization depended on annealing temperature. The perovskite grains were textured predominantly along the (110) direction. The grain size was about 140 nm and almost unchanged under different annealing temperature. With the annealing temperature increasing, the degree of crystallization was improved. La0.5Sr0.5CoO3(LSCO) thin film was grown on Pt/Ti/Si as buffer layer. PZT with LSCO buffer layer was intensively (110) preferred orientation and the morphology of PZT thin film changed greatly.

Ag films on tinning glass substrates were fabricated by modified silver-mirror (Tollen’s) reaction with the advantage of low-cost, simple and quick fabrication process. The obtained Ag films were served as sacrificial materials for preparation of Ag/Au nanocomposite films by immersing in a chlorauric acid (HAuCl4) solution at room temperature. After a short time of galvanic replacement reaction, Ag/Au bimetallic nanostructures were synthesized with “concave” structures. The morphology, properties and composition of the Ag and Ag/Au nanocomposite films were analyzed by using scanning electron microscopy (SEM), UV-visible spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDS) and surface enhanced Raman scattering (SERS). SEM images displayed that the large area of Ag film and Ag/Au bimetallic nanostructures experienced structural evolution process during galvanic reaction. The UV-Vis spectra showed the absorbencies characterization of Ag film and Ag/Au nanocomposite films. SERS measurements using methylene blue as an analyte showed that SERS intensities of bimetallic films were enhanced significantly compared with that of pure Ag films. The SERS enhancement ability of Ag/Au bimetallic films was dependent on the immersion time for galvanic replacement reaction.

Bismuth nanocap arrays have been prepared by vacuum depositing Bi films onto the surfaces of self-assembled monolayer arrays of SiO2 nanoparticles. The surface morphologies, structures, and optical properties of the obtained samples have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and ultraviolet–visible–near infrared (UV–vis–NIR) spectrophotometer. TEM and AFM images indicated that the SiO2/Bi composite nanoparticles were incompletely encapsulated and their surfaces were relatively rough. UV–vis–NIR absorption spectra showed that Bi nanocap arrays had strong and tunable surface plasmon resonance peaks in the visible and near infrared regions, which were dependent dramatically on the relative ratio of the SiO2 core diameter to the Bi cap thickness.

Gold nanocaps were prepared by vacuum depositing gold films onto self-assembled monolayers of SiO2nanoparticles, and characterized using SEM, AFM and XRD. Its antibacterial activity was investigated. It was found that gold films with cubic structure have completely covered self-assembled monolayers of SiO2nanoparticles. The gold nanocap, comprising of 20 nm gold film and 450 nm SiO2nanoparticles, possesses high antibacterial activity.

Silver (Ag) semishells arrays were fabricated with a seed-mediated growth method by depositing silver films on top of self-assembly close-packed monolayer of SiO2nanoparticles. The surface morphologies and optical properties were characterized using TEM, SEM and UV-Vis spectroscopy. The surface-enhanced Raman scattering (SERS) activities of these nanostructures were investigated using methylene blue (MB) as probe molecule. The enhancement factor was estimated to be as large as 2.05×1010. The results revealed that these Silver nanostructures are good SERS-active substrates.

Copper nanocap arrays, consisting of a SiO 2 core with a Cu cap, were prepared by chemical synthesis combined with physical evaporation technique. The obtained samples were characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, and ultraviolet-visible-near-infrared spectrophotometer. The copper nanocap arrays were found to exhibit tunable surface plasmon resonance (SPR) absorption peaks that were red-shifted as the ratio of the SiO 2 core diameter to the Cu cap thickness increased. While the cap thickness varied between 20 nm and 50 nm, the SPR peak shifted from 1650 nm to 1230 nm. While the core diameter varied between 140 nm and 400 nm, the longitudinal SPR peak shifted from 1243 nm to 1830 nm.

A new long-lasting phosphorescence phosphor, Ca 2 SnO 4 :Sm 3+ , which emits orange light upon UV-excitation, has been successfully obtained by a conventional high-temperature solid-state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction, photoluminescence, excited-state decay curve and long-lasting phosphorescence decay curve. After irradiation with 252-nm ultraviolet light, Ca 2 SnO 4 :Sm 3+ emits intense orange afterglow originating from the 4 G 5/2 to 6 H J ( J = 5/2,7/2,9/2) transitions. The afterglow decay curve of the Sm 3+ -doped Ca 2 SnO 4 phosphor indicates both fast and slow decay components. Due to the presence of the latter one, the afterglow can be clearly observed with the naked eyes in the dark for more than 1 h after. The possible mechanism of this long-lasting phosphorescence has also been discussed based on the experimental results.

We report on a luminescent phenomenon in Sm 3+ -doped Sr 3 Sn 2 O 7 afterglow phosphor. XRD, photoluminescence, afterglow emission spectra and long-lasting phosphorescence decay curve are used to characterize this phosphor. After irradiation by a 267-nm UV light for 5 min, the Sm 3+ -doped Sr 3 Sn 2 O 7 phosphor emits intense reddish-orange emitting afterglow from the 4 G 5/2 to 6 H J ( J = 5/2, 7/2, 9/2) transitions, and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source. Photoluminescence spectra reveal that the reddish-orange light-emitting long-lasting phosphorescence originate from the mixture of Sm 3+ characteristic transitions. The afterglow decay curve of the Sm 3+ -doped Sr 3 Sn 2 O 7 phosphor contains a fast decay component and another slow decay one. The possible mechanism of this reddish-orange light-emitting LLP phosphor is also discussed based on the experiment results.

Green-light-emitting long-lasting phosphorescence phosphor, Eu2+ activated calcium magnesium chlorosilicate Ca8Mg(SiO4)4Cl2, has been prepared by a modified solid-state reaction method using Ca2SiO4:Eu2+ as a precursor. Its properties have been discussed and analyzed utilizing XRD, photoluminescence, excited-state decay curve and long-lasting phosphorescence decay curve. Upon UV light excitation, the emission spectrum of Ca8Mg(SiO4)4Cl2:Eu2+ phosphor is composed of two separate bands centered at 425 nm and 505 nm, respectively. Furthermore, after irradiation by a 320-nm UV light for 3 min, the 2% Eu2+-doped Ca8Mg(SiO4)4Cl2 phosphor emits intense green-light-emitting afterglow from the 4f65d1→4f7 transition of Eu2+, and its afterglow can be seen with the naked eye in the dark clearly for more than 3 h after removal of the excitation source. The disappearance of the high-energy 425 nm band in the afterglow emission spectrum is explained by its different crystallographic sites. The afterglow decay curve of the Eu2+-doped Ca8Mg(SiO4)4Cl2 phosphor contains a fast decay component and another slow decay one. The possible mechanism of this long-lasting phosphorescence phosphor is also discussed based on the experimental results.

A series of rare-earth ion-doped gadolinium oxysulfide phosphors Gd 2 O 2 S:RE 3+ , Ti, Mg (RE = Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) were synthesized by solid-state reaction. The excitation and photoluminescence spectra, afterglow spectra, afterglow decay curves and thermoluminescence spectra of the phosphors were examined. According to the afterglow spectra, gadolinium oxysulfide doped with rare-earth ions were classified into three groups. When rare earth ions such as Eu 3+ , Sm 3+ , Dy 3+ , Ho 3+ , Er 3+ and Tm 3+ were introduced into the Gd 2 O 2 S host, their characteristic emission as well as that from Gd 2 O 2 S:Ti, Mg were observed. In case of Yb 3+ and Nd 3+ , only the broadband luminescence of Gd 2 O 2 S:Ti, Mg was obtained. Gadolinium oxysulfide doped with Pr 3+ , Tb 3+ and Ce 3+ did not show afterglow emission. The calculated trap energy levels of the samples were compared. The role of Ti and Mg ions and a potential mechanism for persistent luminescence in the samples were discussed.

Erbium-doped MoO3−Bi2O3−TeO2 (MBT) glasses suitable for broadband optical amplifier applications have been fabricated and characterized optically. The maximum phonon band of undoped glasses is at 915 cm−1, and the emission from the Er3+: 4I13/2 → 4I15/2 transition locates around 1.53 μm with a full width at half maximum (FWHM) of ∼80 nm. The lifetime and quantum efficiency of the 4I13/2 level are 2.13 ms and ∼90%, respectively. Under the same measurement condition, the upconversion emission intensities at 550 nm in Er3+-doped MBT glasses is about 30 times weaker than that in Er3+-doped Na2O−ZnO−TeO2 (NZT) glasses.

Resonant energy transfer between Pr 3+ and Yb 3+ ions has been studied in tellurite glasses. The energy absorbed by Pr 3+ is transferred efficiently to Yb 3+ , and fluorescence at around 1 μm wavelength is observed. The energy transfer efficiencies for the 3 P 0 → 3 F 2 and 1 D 2 → 1 G 4 transitions in 0.5 wt% Pr 3+ –1.0 wt% Yb 3+ codoped tellurite glasses are ∼68% and ∼84%, respectively, and the emission intensity of the 1 G 4 → 3 H 5 transition of Pr 3+ does not show any significant change, due to a possible back transfer energy from the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ to the 1 G 4 level of Pr 3+ .

Tm 3+ -doped Li2O-SrO-ZnO-Bi2O3 (LSZB) glasses that are suitable for optical amplifier applications have been fabricated through the conventional melt-quenching method, and the spectroscopic properties of Tm 3+ in the glasses were characterized. The density, the refractive indices, the optical absorption, the Judd-Ofelt parameters Ωt, and the spon- taneous transition probabilities of the glasses were measured and calculated. Using the least-squares fitting method, the Judd-Ofelt intensity parameters Ωt were found to be 2=4.2910 -20 cm 2 , 4=1.1610 -20 cm 2 , and 6=0.8410 -20 cm 2 . Intense 1.47-m fluorescence was observed in these glass systems under 785-nm excitation. The emission peak from the Tm 3+ : 3 H4  3 F4 transition locates around 1.47-µm with a bandwidth is ~112 nm, which is significantly wider than the bandwidth of Tm 3+ -doped ZBLAN at 80nm but smaller than that in KBG glasses. The results indicate that Tm 3+ -doped LSZB glasses is a promising host material for applications in optical amplifiers.

Researchers propose and demonstrate Sodium Zinc Molybdenum Tellurite glasses (Na2O-ZnO-MoO3-TeO2 or NZMT) as suitable hosts for rare earth ion thulium (Tm3+) operating at 1.47 m wavelength. The density, the refractive indices, the optical absorption have been measured. The Judd-Ofelt intensity parameters Ω2, Ω4, Ω6, the radiative rates, the branching ratios, and the fluorescence lifetimes were calculated according to Judd-Ofelt theory. Intense 1.47 m fluorescence was observed in these glass systems under 973- nm excitation. The bandwidth of the 3H4  3F4 transition in NZMT glass is ~100 nm, which is significantly larger than that of fluoride glasses but less than that in KBG glasses. Measured fluorescence lifetimes of the 3F4 3H6 and 3H4 3F4 decay at room temperature were 2.842 and 0.323 ms respectively, and their quantum efficiencies were approximately 100% and 88.9%. From the data, it appears that Tm3+ doped NZMT glasses are promising materials for waveguide lasers and amplifiers operation at 1.40-1.52 m wavelength range.

A series of new long-lasting phosphor Gd 2 O 2 S: x Er,Ti are prepared by the conventional high-temperature solid-state method and their luminescent properties are systematically investigated in this paper. The characteristic afterglow emission of Er, which is due to the transition of 4 F 9/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 , is reported for the first time. XRD, photoluminescence, long-lasting phosphorescence and decay curves are used to characterize the synthesized phosphors. The possible energy transfer mechanism of Gd 2 O 2 S: x Er,Ti is also investigated.

Novel terbium chelate doped silica fluorescent nanoparticles were prepared and characterized. The preparation was carried out in water-in-oil (W/O) microemulsion containing monomer precursor (pAB-DTPAA-APTEOS), Triton X-100, n-hexanol, and cyclohexane by controlling copolymerization of tetraethyl orthosilicate and 3-aminopropyl-triethyloxysilane. The nanoparticles are spherical and uniform in size, about 30 nm in diameter, strongly fluorescent, and highly stable. The amino groups directly introduced to the surface of the nanoparticles using APTEOS during preparation made the surface modification and bioconjugation of the nanoparticles easier. The nanoparticles are expected as an efficient time-resolved luminescence biological label.

We report a general chemical strategy for producing reduced-symmetry metallodielectric nanoparticles, nanocups, and nanocaps that combines nanoscale masking techniques and nanoparticle-seeded electroless plating. Using this approach, silica nanoparticles with a gold cup-shaped shell and, alternatively, a gold cap, are obtained. The plasmon response of both nanostructures is a sensitive function of orientation of the nanostructure with respect to the direction and polarization of incident light. This orientation dependence is examined experimentally by studying the extinction spectra of oriented nanocups and nanocaps on transparent substrates, and is also evaluated theoretically using a three-dimensional finite difference time domain (FDTD) method.

Alkaline silver colloid with better stability and uniformity was obtained by adding appropriate amount of NaOH to synthesis reaction. The performance of the Ag colloid as surface enhanced Raman scattering (SERS) active substrate was evaluated by methylene blue as the probe molecules and achieved well Raman spectra. The concentration of methylene blue had no effect on the adsorptive behavior of methylene blue on alkaline silver colloid surface in comparison with normal silver colloid. The basic reason for this phenomenon is preferential adsorption of alkaline silver colloid for sulfur atoms of methylene blue so as to increase the intensity of 451 cm-1 Raman peak consistently. The amounts of methylene blue added to alkaline Ag colloid and time-evolution of Raman spectra were also investigated. Additionally, the alkaline silver colloid was prepared to be silver spot and applied to detect melamine doped milk. The relationship of the doping amount of melamine and the Raman signal intensity was obtained. The linearity relationship in the concentration range between 3 and 60 mg.L-1 with detect limit 0.28 mg.L-1 was achieved based on the intensity of 691 cm-1 Raman peak This method required only 5 microL sample size and 5 s for detection and suggested that this presented method with its advantages of speediness, briefness and lower cost has a good application foreground.

We have obtained resonance Raman spectra and absolute Raman cross section measurements at eight excitation wavelengths in the A‐band and B‐band absorptions of bromoiodomethane in cyclohexane solution. The resonance Raman intensities and absorption spectra were simulated using a simple model and time‐dependent wave packet calculations. Normal mode vibrational descriptions were used with the results of the calculations to find the short‐time photodissociation dynamics in terms of internal coordinates. The A‐band short‐time photodissociation dynamics indicate that the C–I bond becomes much longer, the C–Br bond becomes smaller, the I–C–Br angle becomes smaller, the H–C–Br angles become larger, the H–C–I angles become smaller, and the H–C–H angle becomes a bit smaller. The B‐band short‐time photodissociation dynamics indicate the C–Br bond becomes much longer, the C–I bond becomes slightly longer, the I–C–Br angle becomes smaller, the H–C–I angles become larger, the H–C–Br angles become smaller, and the H–C–H angle becomes slightly smaller. Both the A‐band and B‐band short‐time photodissociation dynamics appear to be most consistent with an impulsive ‘‘semi‐rigid’’ radical model qualitative description of the photodissociation with the CH2Br radical changing to a more planar structure in the A‐band and the CH2I radical changing to a more planar structure in the B band. We have carried out a Gaussian deconvolution of the A‐band and B‐band absorption spectra of bromoiodomethane, as well as iodomethane and bromomethane. The absorption spectra, resonance Raman intensities, and short‐time photodissociation dynamics suggest a moderate amount of coupling of the C–I and C–Br chromophores.

The new orange-emitting title phosphor is synthesized by solid state reaction of stoichiometric mixtures of CaCO3, SnO2, and Sm2O3 (air, alumina crucible, 1400 °C, 4 h) and characterized by powder XRD and photoluminescence spectroscopy.

The title phosphor is synthesized by solid state reaction of Ca2SiO4:Eu2+ (obtained from CaCO3, SiO2, and Eu2O3 in alumina crucibles in a reducing 95%/5% N2/H2 gas flow at 1200 °C for 3 h), MgCl2, and NH4Cl as a flux (N2, 900 °C, 3 h).

Green-emitting LaF3:Ce, Tb phosphor nanoparticles were synthesized by a simple hydrothermal method and characterized by XRD, TEM and fluorescence spectra. The prepared samples had a hexagonal shape, fine size (30 nm), and high brightness under ultraviolet, and the structure of LaF3 remained unchanged after being doped with Ce3+ and Tb3+ ions. The blue Ce3+ emission centered at 261 nm is efficiently quenched in the samples of LaF3:Ce, Tb, in which the dominant emission is in the green at 544 nm, originating from the doped Tb3+ ions' transition of (5)D4 to (7)F5. Excitation spectra of the LaF3:Ce, Tb, observed at 544 nm, consist of both contributions from Ce3+ and Tb3+ ions. There is energy transfer of Ce3+ --Tb3+ in this system. The energy transfer mechanism was discussed. Above all, the phosphor nanoparticles have high photoluminescence intensity even without any calcination, about twice that of bulk materials prepared by high temperature solid synthesis, and the intensity is also stronger than calcined phosphor nanoparticles.

LaF 3 :Eu 3+ nanoparticles were prepared by a simple hydrothermal process at low temperature and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence spectrum. Well-dispersed nanoparticles with an average size of 30 nm and a hexagonal shape were obtained. The influences of reaction temperature and time on the preparation and luminescence of LaF 3 :Eu 3+ nanoparticles were investigated. Luminescent quenching occurred at a much higher concentration (∼25 mol%) and stronger luminescent intensity than in bulk LaF 3 :Eu 3+ . Fluorescence intensity of the LaF 3 :Eu 3+ nanoparticles varied remarkably with calcination temperatures. It was found that samples without any further calcinations can emit quite strong fluorescence.

We propose and demonstrate potassium bismuth gallate (KBG) glasses as suitable hosts for the rare-earth ion Tm3+ (thulium) operating at the 1.47-μm wavelength. The optical properties of Tm3+-doped KBG glasses were investigated. The bandwidth of the 3H4→3F4 transition is ∼120 nm and is higher than that of Tm3+-doped, tellurite-based glasses. The measured fluorescence lifetime is 0.15 ms at room temperature, and the quantum efficiency is 88%. Multiphonon relaxation rates for various transitions were evaluated and compared with other glass hosts. The energy transfer in Tm3+–Ho3+-codoped KBG glasses was also investigated, and these results indicate that Tm3+-doped KBG glasses are promising candidates for efficient broadband optical amplifiers operating in the 1.47-μm wavelength range.

A rare-earth ion, namely erbium, was doped into silicon (Si) using thermal indiffusion. Codoping using ytterbium oxide (Yb2O3) and germanium (Ge) to increase photoluminescence (PL) intensity was also demonstrated, and the effect of different Yb/Er ratios on Si was studied. Room temperature PL intensity relative to Er-diffused sample was found to increase by ∼30 times using Yb/Er (27/1) codopant. When a SiGe/Yb/Er layer was used, room temperature PL intensity was further increased to more than 60 times.