Hybrid Laser Technology for Creation of Doped Biomedical Layers

Hybrid laser technologies for deposition of thin films and basic schemes of combination of pulsed laser deposition (PLD) with magnetron sputtering and RF discharges or two lasers or three laser deposition systems are presented. Experiences with deposition of chromium doped diamond-like carbon (DLC) films for coating of prostheses are described. Layers of different chromium concentrations were prepared using hybrid systems (PLD + magnetron sputtering or by double PLD). Results of physical and mechanical characterization of film properties and biomedical tests of trivalent and toxic hexavalent chromium are given. Experiences with double laser deposition of DLC layers doped with silver are also mentioned.

Ce3+掺杂磷酸盐玻璃的紫外与可见光学性能

研究了基于钆和钠磷酸盐Ce3+掺杂磷酸盐玻璃的紫外吸收和发射光谱.与不含Ce3+的磷酸盐玻璃相比,掺Ce3+的样品紫外吸收边向长波方向移动,发射光谱也随玻璃组成的变化发生相应地红移.该现象的解释基于玻璃光碱度的变化,光碱度不仅与碱金属含量有关,也与O/O值有关.O/P值与PO4单元中的非桥氧数成比例,并且对玻璃的整体光碱度起着主要的决定作用.

Ce3+对磷酸盐闪烁玻璃耐辐射性能的影响

研究了空气气氛下制备的掺Ce3+磷酸盐闪烁玻璃.XPS分析结果显示,玻璃网络结构中的铈离子以低化合价(三价)形式存在.分别测试了含Ce3+及不含Ce3+玻璃样品在辐射前及经特定剂量辐射后的紫外可见透过光谱.实验结果表明,含Ce3+玻璃在大于390nm波长处的辐射诱导吸收带消失或明显减弱.通过计算样品的辐射诱导吸收系数μ发现Ce3+离子的引入有效提高了磷酸盐闪烁玻璃的抗辐射能力.

High-precision group-delay dispersion measurements of optical fibers via fingerprint-spectral wavelength-to-time mapping

The group-delay dispersion of an optical fiber was measured with the time-of-flight method, using fingerprint-like characteristic spectra from a mode-locked fiber laser source. To determine the group-delay dispersion up to the fourth order, least-squares fitting was applied to the overall time waveform mapped on the time axis for the fingerprint-spectral broadband pulses through a long optical fiber. The analysis of all 4003 data points reduced statistical uncertainty, and provided second-, third-, and fourth-order dispersion with uncertainties of 0.02%, 0.4%, and 4%,respectively.

EUV ablation of organic polymers at a high fluence

A preliminary investigation on short-wavelength ablation mechanisms of poly(methyl methacrylate)(PMMA) and poly(1,4-phenylene ether ether-sulfone)(PPEES) by extreme ultraviolet(EUV) radiation at 13.5 nm using a table-top laserproduced plasma from a gas-puff target at LLG(Gttingen) and at 46.9 nm by a 10 Hz desktop capillary discharge laser operated at the Institute of Physics(Prague) is presented.Ablation of polymer materials is initiated by photoinduced polymer chain scissions.The ablation occurs due to the formation of volatile products by the EUV radiolysis removed as an ablation plume from the irradiated material into the vacuum.In general,cross-linking of polymer molecules can compete with the chain decomposition.Both processes may influence the efficiency and quality of micro(nano)structuring in polymer materials.Wavelength is a critical parameter to be taken into account when an EUV ablation process occurs,because different wavelengths result in different energy densities in the near-surface region of the polymer exposed to nanosecond pulses of intense EUV radiation.

HIGH-FREQUENCY DIELECTRIC SPECTROSCOPY OF BaTiO_(3)CORE-SILICA SHELL NANOCOMPOSITES:PROBLEM OF INTERDIFFUSION

Three types of BaTiO3 core-amorphous nanoshell composite ceramics were processed from the same core-shell powder by standard sintering,spark-plasma sintering and two-step sintering techniques and characterized by XRD,HRSEM and broadband dielectric spectroscopy in the frequency range 10^(3)-10^(13)Hz including the THz and IR range.The samples differed by porosity and by the amount of interdiffusion from the cores to shells,in correlation with their increasing porosity.The dielectric spectra were also calculated using suitable models based on effective medium approximation.The measurements revealed a strong dielectric dispersion below the THz range,which cannot be explained by the modeling,and whose strength was in correlation with the degree of interdiffusion.It is assigned to an effect of the interdiffusion layers,giving rise to a strong interfacial polarization.It appears that the high-frequency dielectric spectroscopy is an extremely sensitive tool for detection of any gradient layers and sample inhomogeneities even in dielectric materials with negligible conductivity.

Targets for high repetition rate laser facilities:needs,challenges and perspectives

A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.

A new oxidovanadium(Ⅳ) Schiff base complex containing asymmetric tetradentate ONN0O0Schiff base ligand:Synthesis,characterization,crystal structure determination,thermal study and catalytic activity

After synthesis of an asymmetric tetradentate ONN＇O＇ Schiff base ligand （H2L） followed by reaction of the synthesized H2L with an equimolar mixture of methanolic solutions of the VO（acac）2, a new oxidovanadium（IV） Schiff base complex （VOL） was synthesized. The Schiff base ligand and its complex were characterized by FT-IR and UV-vis spectra and C, H, N analysis, The crystal structure of VOL was also determined by single crystal X-ray analysis. The VOL complex crystallizes in monoclinic space group Cc. The Schiffbase ligand acts as a tetradentate ligand through its two＇iminic nitrogens and two phenolic and acetylacetonate oxygens. Thermogravimetric analysis of the VOL showed that it decomposes in two steps and converts to mixed vanadium oxides at 477℃. In addition, thermal decomposition of the VOL complex in air at 660 ℃ leads to formation of V2O5 nanoparticles with the average size estimated from XRD 49 nm. The catalytic activity of the VOL complex was investigated in the epoxidation reaction and different reaction parameters were optimized. The results showed that the cyclic alkenes were efficiently converted to the corresponding epoxides, whereas the VOL did not appreciably convert the linear alkenes.