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The nano-precursors in the subsurface of Nd:YLF crystal were limiting factor that decreased the laser-induced damage threshold (LIDT) of HfO(2)/SiO(2) high reflection (HR) coatings irradiated from crystal-film interface. To investigate the contribution of electric-field (E-field) to laser damage originating from nano-precursors and then to probe the distribution of vulnerable nano-precursors in the direction of subsurface depth, two 1064 nm HfO(2)/SiO(2) HR coatings having different standing-wave (SW) E-field distributions in subsurface of Nd:YLF c5424181043036123rystal were designed and prepared. Artificial gold nano-particles were implanted into the crystal-film interface prior to deposition of HR coatings to study the damage behaviors in a more reliable way. The damage test results revealed that the SW E-field rather than the travelling-wave (TW) E-field contributed to laser damage. By comparing the SW E-field distributions and LIDTs of two HR coating designs, the most vulnerable nano-precursors were determined to be concentrated in a thin redeposition layer that is within 100 nm from the crystal-film interface.

A comparative study of laser induced damage of HfO2/SiO2 and TiO2/SiO2 mirrors at 1064 nm has been carried out. One TiO2/SiO2 mirror with absorption of 300 ppm and two HfO2/SiO2 mirrors with absorption of 40 and 4.5 ppm were fabricated using electron beam evaporation method. For r-on-1 test, all HfO2/SiO2 mirrors with low average absorption are above 150 J/cm2 at 10 ns. However, the TiO2/SiO2 mirrors with high average absorption are just 9.5 J/cm2, which are probably due to the rather high absorption and rather low band gap energy. Meanwhile, all the samples were irradiated from front and back side respectively using the raster scan test mode. In case of front side irradiation, it is found that: for TiO2/SiO2 high reflectors, the representative damage morphologies are shallow pits that were probably caused by absorbing centers. However, for HfO2/SiO2 high reflectors, the dominant damage morphologies are micrometer-sized nodules ejected pits and the delamination initiating from the pits. The absorption of HfO2/SiO2 coatings is low enough to have minor influence on the laser damage resistance. In case of backside irradiation, the morphology of TiO2/SiO2 mirrors is mainly center melted pits that are thermal melting induced damage. Meanwhile, HfO2/SiO2 mirrors with isometrical fracture rings damage morphology are thermal induced stress damage.

Hafnium oxide (HfO(2)) films were deposited by the ultrasonic spray pyrolysis process. The films were synthesized from hafnium chloride as raw material in deionized water as solvent and were deposited on corning glass substrates at temperatures from 300 to 600 degrees C. For substrate temperatures lower than 400 degrees C the deposited films were amorphous, while for substrate temperatures higher than 450 degrees C, the monoclinic phase of HfO(2) appeared. Scanning electron microscopy showed that the film's surface resulted rough with semi-spherical promontories. The films showed a chemical composition close to HfO(2), with an Hf/O ratio of about 0.5. UV radiation was used in order to achieve the thermoluminescent characterization of the films; the 240 nm wavelength induced the best response. In addition, preliminary photoluminescence spectra, as a function of the deposition temperatures, are shown., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The isotope (177)Lu is used in nuclear medicine and biology for in vivo applications as a radioactive label of various targeting agents. To extend the availability of no-carrier added (177)Lu, we investigated the feasibility of its production in a proton accelerator. Tantalum and Hf targets were irradiated and chemically processed to determine the radioisotope yield and cross-sections. The largest cross-sections (approximately 20 mb) were found for the Hf target at 195 MeV; however, the presence of co-produced Lu isotopes may limit the product applications. The results are in good agreement with theoretical data calculated using computer codes MCNPX and ORIGEN2S. Production of relevant medical isotopes such as (167)Tm and (169)Yb from the above targets is discussed as well.

A new bluish-white long-lasting phosphorescent material, Hf4+-doped b-Zn3(PO4)2, was prepared by the conventional high-temperature solid-state method. The photoluminescence (PL) spectrum reveals that it exhibits a strong blue emission band centred at 470 nm, with asymmetry on the long wavelength side; this material emits bluish-white light and shows strong afterglow phosphorescence after it is excited with a 254 nm UV lamp. The phosphorescence lasts nearly 40 min in the light perception of the dark-adapted human eye (0.32 mcd/m(2)). The possible phosphorescence mechanism is also analysed., ((c) 2008 John Wiley & Sons, Ltd.)