X-ray spectra induced in highly charged Ar-40(q+) interacting with Au surface

By use of optical spectrum technology, the spectra of X-ray induced by highly charged Ar-40(q+) ions interacting with Au surface have been studied. The results show that the argon K alpha X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ ion, with electronic configuration 1s(2) in its ground state below the solid surface. The yield of the projectile K alpha X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy.

ATOMIC PHYSICS RESEARCHES AT COOLER STORAGE RING IN LANZHOU

The commissioning of the cooler storage rings (CSR) was successful, and the facility provides new possibilities for atomic physics with highly charged ions. Bare carbon, argon ions, were successfully stored in the main ring CSRm, cooled by cold electron beam, and accelerated up to 1 GeV/u. Heavier ions as Xe44+ and Kr28+ were also successfully stored in the CSRs. Both of the rings are equipped with new generation of electron coolers which can provide different electron beam density distributions. Electron-ion interactions, high precision X-ray spectroscopy, complete kinematical measurements for relativistic ion-atom collisions will be performed at CSRs. Laser cooling of heavy ions are planned as well. The physics programs and the present status will be summarized.

Effect of substrate and annealing on the structural and optical properties of ZnO:Al films

ZnO:Al thin films with c-axis preferred orientation were deposited on glass and Si substrates using RF magnetron sputtering technique. The effect of substrate on the structural and optical properties of ZnO:Al films were investigated. The results showed a strong blue peak from glass-substrate ZnO:Al film whose intensity became weak when deposited on Si substrate. However, the full width at half maxima (FWHM) of the Si-substrate ZnO:Al (0 0 2) peaks decreased evidently and the grain size increased. Finally, we discussed the influence of annealing temperature on the structural and optical properties of Si-substrate ZnO:Al films. After annealing, the crystal quality of Si-substrate ZnO:Al thin films was markedly improved and the intensity of blue peak (similar to 445 nm) increased noticeably. This observation may indicate that the visible emission properties of the ZnO:Al films are dependent more on the film crystallinity than on the film stoichiometry. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

Light-emitting-diode-induced fluorescence detector for capillary electrophoresis using optical fiber with spherical end

A simple fluorescence detector for capillary electrophoresis (CE) using a blue light-emitting-diode (LED) as excitation source is constructed and evaluated. An optical fiber was used to collect the fluorescence, and a flat end of the fiber was modified to spherical end, resulting in 50% increase of efficiency over the flat end. A simple device for optical alignment of the fibers and capillary column was designed. The concentration and mass detection limits for fluorescein were 1.8 x 10(-7) Mol l(-1) and 4.3 femol, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.

An Efficient Nanocrystalline La2O3:Tm3+ Blue Phosphor for Field-Emission Displays with High Color Purity

Nanocrystalline Tm3+-doped La2O3 phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction, field-emission scanning electron microscopy, photoluminescence, and cathodoluminescence spectra were utilized to characterize the synthesized phosphors. Under the excitation of UV light (234 nm) and low-voltage electron beams (1-3 kV), the Tm3+-doped La2O3 phosphors show the characteristic emissions of Tm3+(D-1(2), (1)G(4)-F-3(4), H-3(6) transitions).

Blue-light emission of mesoporous SBA-15 covalently bonded with carbazole chromophore

Much attention has been paid to carbazole derivatives for their potential applications as optical materials. For the first time, the blue-light-emitting carbazole chromophore has been covalently bonded to the ordered mesoporous SBA-15 (The resultant hybrid mesoporous materials are denoted as carbazole-SBA-15) by co-condensation of tetraethoxysilane (TEOS) and prepared compound 3-[N-3-(triethoxyilyl)propyl]ureyl-9-ethyl-carbazole (denoted as carbazole-Si) in the presence of Pluronic P123 surfactant. The results of H-1 NMR and Fourier transform infrared (FTIR) reveal that carbazole-Si has been successfully synthesized.

LaGaO3 : A (A=Sm3+ and/or Tb3+) as promising phosphors for field emission displays

LaGaO3:Sm3+, LaGaO3:Tb3+ and LaGaO3: Sm3+, Tb3+ phosphors were prepared through a Pechini-type sol-gel process. X-Ray diffraction, field emission scanning electron microscopy, photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the synthesized phosphors. Under excitation with ultraviolet light (250-254 nm), the LaGaO3: Sm3+, LaGaO3: Tb3+ and LaGaO3: Sm3+, Tb3+ phosphors mainly show the characteristic broadband emission (from 300 to 600 nm with a maximum around 430 nm) of the LaGaO3 host lattice, accompanied by the weak emission of Sm3+ ((4)G(5/2) -> H-6(5/2), H-6(7/2), H-6(9/2) transitions) and/or Tb3+ (D-5(3,4) -> F-7(6,5,4,3) transitions). However, under excitation by low-voltage electron beams (1-3 kV), the LaGaO3: Sm3+, LaGaO3: Tb3+ and LaGaO3: Sm3+, Tb3+ phosphors exhibit exclusively the characteristic emissions of Sm3+ and/or Tb3+ with yellow (Sm3+), blue (Tb3+, with low concentrations) and white (Sm3+ + Tb3+) colors, respectively.

Solvothermal synthesis of well-dispersed MF2 (M = Ca, Sr, Ba) nanocrystals and their optical properties

MF2 (M = Ca, Sr, Ba) nanocrystals (NCs) were synthesized via a solvothermal process in the presence of oleic acid and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectra, UV/vis absorption spectra, photoluminescence (PL) excitation and emission spectra, and lifetimes, respectively. In the synthetic process, oleic acid as a surfactant played a crucial role in confining the growth and solubility of the MF2 NCs. The as-prepared CaF2, SrF2 and BaF2 NCs present morphologies of truncated octahedron, cube and sheet in a narrow distribution, respectively.

Preparation of Prussian blue@Pt nanoparticles/carbon nanotubes composite material for efficient determination of H2O2

In this study, the fabrication of an efficient amperometric hydrogen peroxide sensor with favorable properties is presented. Prussian blue (PB) was catalytically synthesized by Pt nanoparticles (Pt-nano) from ferric ferricyanide aqueous solution to form PB@Pt-nano hybrid, and it was confirmed by transmission electron microscope (TEM) and optical spectra. The electrochemical behavior of PB@Pt-nano was highly improved through its integration with poly(diallyldimethylammonium chloride) modified carbon nanotubes (PCNTs).

Synthesis, characterization and optical property of flower-like indium tin sulfide nanostructures

We report a simple method for novel flower-like In4SnS8 nanostructure synthesis. A flower-like In4SnS8 nanostructure was synthesized via a one-pot hydrothermal route using the biomolecule L-cysteine as a sulfur source. The structure was characterized using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption analysis and photoluminescence spectra. This flower-like structure consists of crosslinked nanoflakes and possesses good thermostability and a high BET surface area.

Multifunctional Hydroxyapatite Nanofibers and Microbelts as Drug Carriers

Luminescent, mesoporous, and bioactive europium-doped hydroxyapatite (HAp:Eu3+) nanofibers and microbelts have been prepared by a combination of sol-gel and electrospinning processes with a cationic surfactant as template. The obtained multifunctional hydroxyapatite nanofibers and microbelts, which have mesoporous structure and red luminescence, were tested as drug carriers by investigating their drug-storage/release properties with ibuprofen (IBU) as model drug. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution (HR) TEM, FTIR spectroscopy, N-2 adsorption/desorption, photoluminescence (PL) spectra, and UV/Vis spectroscopy were used to characterize the structural, morphological, textural, and optical properties of the resulting samples.

Controllable Red, Green, Blue (RGB) and Bright White Upconversion Luminescence of Lu2O3:Yb3+/Er3+/Tm3+ Nanocrystals through Single Laser Excitation at 980 nm

Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode laser excitation of 980 nm, the bright blue emissions of Lu2O3:Yb3+, Tm3+ nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-> H-3(6) transition of Tm3+. The bright green UC emissions of Lu2O3:Er3+ nanocrystals appeared near 540 and 565 nm were observed and assigned to the H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) transitions, respectively, of Er3+. The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb3+ in Lu2O3:Er3+ nanocrystals.

Tm3+ and/or Dy3+ doped LaOCl nanocrystalline phosphors for field emission displays

Blue, yellow and white light emissive LaOCl:Tm3+, LaOCl:Dy3+ and LaOCl: Tm3+, Dy3+ nanocrystalline phosphors were synthesized through the Pechini-type sol-gel process. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and cathodoluminescence (CL) spectra were used to characterize the samples. Under UV radiation (229 nm) and low-voltage electron beam (0.5-5 kV) excitation, the Tm3+-doped LaOCl phosphor shows a very strong blue emission corresponding to the characteristic transitions of Tm3+ (D-1(2), (1)G(4) -> F-3(4), H-3(6)) with the strongest emission at 458 nm. The cathodoluminescent color of LaOCl:Tm3+ is blue to the naked eye with CIE coordinates of x = 0.1492, y = 0.0684. This phosphor has better CIE coordinates and higher emission intensity than the commercial product Y2SiO5:Ce3+.

Fabrication and Luminescence Properties of One-Dimensional CaMoO4: Ln(3+) (Ln = Eu, Tb, Dy) Nanofibers via Electrospinning Process

One-dimensional CaMoo(4):Ln(3+) (Ln = Eu, Tb, Dy) nanofibers have been prepared by a combination method of sol-gel and electrospinning process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and low voltage cathodoluminescence (CL) as well as kinetic decays were used to characterize the resulting samples. SEM and TEM analyses indicate that the obtained precursor fibers have a uniform size, and the as-formed CaMoO4:Ln(3+) nanofibers consist of nanoparticles. Under ultraviolet excitation, the CaMoO4 samples exhibit a blue-green emission band with a maximum at 500 nm originating from the MoO42- groups. Due to an efficient energy transfer from molybdate groups to dopants, CaMoO4:Ln(3+) phosphors show their strong characteristic emission under ultraviolet excitation and low-voltage electron beam excitation.

Synthesis and Luminescent Properties of LaAlO3:RE3+ (RE = Tm, Tb) Nanocrystalline Phosphors via a Sol-Gel Process

LaAlO3:Tm3+ and LaAlO3:Tb3+ phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence, and cathodoluminescence (CL) spectra were utilized to characterize the synthesized phosphors. The XRD results reveal that the fully crystalline pure LaAlO3 Phase can be obtained at 800 degrees C. The FE-SEM image indicates that the phosphor samples are composed of aggregated spherical particles with sizes ranging from 40 to 80 nm. Under the excitation of ultraviolet light (230 nm) and low-voltage electron beams (1-3 kV), the LaAlO3:Tm3+ and LaAlO3:Tb3+ phosphors show the characteristic emissions of Tb3+ (D-1(2)-> H-3(6,4),F-3(4) transitions) and Tm3+ (D-5(3,4)-> F-7(6,5,4,3) transitions) respectively. The CL of the LaAlO3:Tm3+ phosphors have high color purity and comparable intensity to the Y2SiO5:Ce3+ commercial product, and the CL colors of Tb3+-doped LaAlO3 phosphors can be tuned from blue to green by changing the doping concentration of Tb3+ to some extent.