Zhang Guo-Bin

Direct, etching of GaAs Crystal Excited by a Vacuum Ultraviolet Lamp

A successful direct, etching system excited by a vacuum ultraviolet hollow-cathode lamp is reported. The result shows that the facility can transfer a mesh pattern exactly and directly to n-type GaAs wafer, which is the same as that direct, etched by synchrotron radiation.

Photoluminescent Properties of ZnO Films Deposited on Si Substrates

The photoluminescence of ZnO films deposited on Si substrates by reactive dc sputtering has been studied by using a synchrotron radiation (SR) light source. The excitation spectra show a strong excitation band around 195 nm related to the 390 nm emission band. Under SR vacuum ultraviolet excitation, a new emission band peaked at 290 nm was found for the first time, besides the ultraviolet emission band (390 nm) and green band (520 nm).

Luminescence Properties of Ca4GdO(BO3)3:RE (RE=Eu3+,Tb3+) under VUV Excitation

We experimentally investigated the VUV excitation luminescence properties of Ca4GdO(BO3)3:RE (RE=Eu3+,Tb3+). Ca4GdO(BO3)3:Eu3+ and Ca4GdO(BO3)3:Tb3+ emitted bright red and green colour light, respectively, under 172 nm excitation, resulting from the favorable position of the host absorption band (186 nm) and efficient energy transfer from Gd3+ to activators (e.g. Eu3+ or Tb3+) by means of secondary absorption in the Ca4GdO(BO3)3 matrix. The f–d transitions of Eu3+ and Tb3+ in the host lattice are depicted.

Concentration and Temperature Dependences of YBO3:Bi3+ Luminescence under Vacuum Ultraviolet Excitation

Bi3+ doped YBO3 phosphors are prepared by solid state reaction and their luminescent properties are investigated by using synchrotron radiation instrument. Concentration and temperature dependences of YBO3:Bi3+ luminescence under VUV/UV excitation is observed. The emission and excitation spectra are assigned, and the mechanism for these phenomena is explored, which result from the energy transfer between Bi3+ ions occupying different sites in YBO3 crystal lattice.

Effects of Annealing Treatments on Luminescence and Scintillation Properties of Ce:Lu3 Al5 O12 Crystal Grown by Czochralski Method

Abstract Ce:Lu 3 Al 5 O 12 single crystals grown in pure N 2 atmosphere by Czochralski method were annealed in oxidizing atmosphere (air) and reducing atmosphere (H 2 + N 2 ), respectively. Effects of annealing treatments on luminescence and scintillation properties of the crystals were investigated. The crystal annealed in air showed the highest luminescence intensity under blue light or vacuum ultraviolet excitation in comparison with that annealed in reducing flux or the as-grown crystal. Under X-ray excitation, crystal annealed in reducing atmosphere had the lowest light yield, and crystal annealed in air had the fastest decay time under 137 Cs 662 keV γ-ray excitation. Different annealing treatments resulted in different luminescence and scintillation properties, which might related with oxygen vacancies or defect existing in the crystals.

Cascade Energy Transfer in CeF3 Crystals

The emission spectra of the CeF3 crystals in UV-visible region and their temperature dependence in the range of 6-453 K under UV, VUV excitation as well as their excitation spectra (4-25 eV) have been studied. The 350 nm emission band from perturbed Ce3+ can be excited by 295.2 and 302.4 nm emissions from the regular Ce3+. The 350 nm emission band, in turn, can excite the emission bands centered at 470 and 535 nm caused by some defects below room temperature. These results show that there is a cascade energy transfer process from regular Ce3+ to quenching centers via perturbed Ce3+ and defect centers in the CeF3. Meanwhile, thermoluminescence, giving peaks at about 240 and 300°C has been discovered, and the corresponding deep traps with depth ~ 1 eV are found to be a kind of quenching center for CeF3 luminescence at room temperature.

Local structure of oxygen-deficient Yttrium oxide

Yttrium oxide thin films have been deposited on Si (100) substrate by using pulsed laser deposition (PLD) method. X-ray diffraction (XRD), hard and soft X-ray absorption spectroscopy (XAFS) are employed to investigate the origin of oxygen vacancies and their influence on the structure and atomic distributions. The XRD results indicate that the Y2O3 thin films strongly orient the (111) axis of the cubic structure. Analyses on the Y K-edge extended X-ray absorption fine structures reveal that the coordination number of Y atoms decreases and the bond length of Y-O contracts due to the loss of oxygen atoms. The X-ray absorption near edge structure analysis together with a theoretical approach further confirms the oxygen vacancies formation and their possible location.

Studies on vacuum ultraviolet spectra of breast tumor tissues

The vacuum ultraviolet (VUV) spectra of breast sickness tissues, benign or malign breast tumors were studied under the excitation of different VUV photons from a synchrotron radiation light source. The excitation spectra of different samples were monitored at 400 nm and 550 nm. The efficient excitation wavelengths were 133 nm, 193 nm and 252 nm, respectively. The differences of their fluorescence spectra were analyzed, and the results showed that their VUV spectra were different for various breast sickness tissues. There were two peaks in the spectrum when these tissues were excited by 133 nm. When 193 nm light was used to excite the tissues, there appeared a three-peak structure. There was only one distinct peak when these tissues were excited by 252 nm light. The differences of VUV spectra reflect the characteristics of various kinds of breast sickness tissues. The VUV fluorescence technique may be used in the diagnoses of breast tumor, especially available in finding the early cancers.

Energy Transfer in Cubic PbF2:Gd Crystals

The emission and excitation spectra of cubic PbF2:Gd were measured. Compared with pure crystals, the emissions from Gd3+ were observed upon cation exciton excitation in lattices, while the emission from intrinsic self-trapped excitons was quenched. It indicates the energy transfer from exciton to the 4f state of Gd3+.

Luminescence of SR irradiated fused quartz

Abstract The properity of amorphous SiO 2 is sensitive to the irradiation of energetic ions, electron beam, X- and γ-rays, even to VUV radiation. The luminescence of a-SiO 2 and irradiated a-SiO 2 has been investigated. Here, we report that the visible light can be emitted under the excitation of Ar + ion laser from the surface of bulk fused quartz which was irradiated by “white” SR in UHV at room temperature. The emission spectrum is an asymmetry band peaked at about 625 nm, with a FWHM of about 20 nm. The SR for irradiation is from the 800 MeV storage ring without any optical elements between the light source and the samples. The vacuum is kept below 5 × 10 −7 Pa, the average beam current is 100mA and the irradiation time is 3 hours. The intensity of the luminescence is rapidly decreased under the excitation of laser. It can stand for half an hour when the power of excited laser light is kept at 2W/cm 2 approximately.