Crystallization of amorphous Ge2Sb2Te5 films induced by a single femtosecond laser pulse

Crystallization is achieved in amorphous Ge2Sb2Te5 films upon irradiation with a single femtosecond laser pulse. Transmission electron microscopy images evidence the morphology of the crystallized spot which depends on the fluence of the ferntosecond laser pulse. Fine crystalline grains are induced at low fluence, and the coarse crystalline grains are obtained at high fluence. At the damage fluence, ablation of the films occurs. (C) 2004 Elsevier Ltd. All rights reserved.

Photobleaching process of xanthene dyes initiated by N-phenylglycine in the polyvinylalcohol film

The parameters such as quantum yield and molar absorption coefficients of the photoinitiator that are responsible for holographic sensitivity in photopolymer material are investigated with a single beam exposure experiment. The influence of exposure intensity, the concentrations of N-phenylglycine and dye on the photobleaching process of xanthenes dyes are presented. In addition, the effect of diphenyliodonium hexafluorophosphate salt on the quantum yield and molar absorption of xanthene dyes is studied. (c) 2005 Elsevier Ltd. All rights reserved.

Si underlayer induced nano-ablation in AgInSbTe thin films

AgInSbTelSi thin films on glass substrates are prepared by dc magnetron sputtering at room temperature. Using Si underlayer as the thermal diffusion layer, the super-resolution nano-ablation holes with a size of 70nm in the AgInSbTe phase change films are obtained by a far-field focused laser experimental setup, with laser wavelength 405nm and objective-lens numerical aperture 0.90. The nano-ablation formation mechanism is analysed and discussed via the thermal diffusion of sample structures.

准分子激光光束均匀技术

由于放电结构及谐振腔的限制，准分子激光光斑呈现不均的分布。介绍了各种均匀器的工作原理，从衡量光束均匀性的各项指标出发，评述分析了各种均匀方法的优缺点及适用范围。

具有高机械强度的掺Er^3＋：TeO2-Nb2O5玻璃的光谱性质研究

熔制了掺铒碲铌玻璃样品（100-X）TeO2-XNb2O5（X=5，10，15，20mol％），测试了其密度、折射率、转变温度、析晶温度、维氏机械强度、吸收光谱、荧光光谱、荧光寿命等参量。利用Judd-Ofelt和McCumber理论分别计算了铒离子强度参量Ωt（t=2，4，6）和受激发射截面σcmi的大小，研究了掺铒碲铌玻璃样品光谱参量对Nb2O5成分的依赖性，并与典型的碲锌钠玻璃（75TeO2-20ZnO-5Na2O）在热学、机械强度、光谱性质和放大品行四个方面进行了比较．

Upconversion luminescence of TM3+/Yb3+ codoped oxyfluoride glasses

Novel oxyfluoride glasses are developed with the composition of 30SiO(2)-15Al(2)O(3)-28PbF(2)-22CdF(2)-0.1TmF(3)-xYbF(3) -(4.9-x) AlF3(x = 0, 0.5, 1.0, 1.5, 2.0) in mol fraction. Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and bear infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm3+: D-1(2) -> F-3(4), (1)G(4) -> H-3(6), (1)G(4) -> F-3(4), and H-3(4) -> H-3(6), respectively, are observed. Due to the sensitization of Yb3+ ions, all the upconversion luminescence intensities are enhanced considerably with Yb3+ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.

Observational constraints on the unified dark matter and dark energy model based on the quark bag model

In this work we investigate if a small fraction of quarks and gluons, which escaped hadronization and survived as a uniformly spread perfect fluid, can play the role of both dark matter and dark energy. This fluid, as developed in [1], is characterized by two main parameters: beta, related to the amount of quarks and gluons which act as dark matter; and gamma, acting as the cosmological constant. We explore the feasibility of this model at cosmological scales using data from type Ia Supernovae (SNeIa), Long Gamma-Ray Bursts (LGRB) and direct observational Hubble data. We find that: (i) in general, beta cannot be constrained by SNeIa data nor by LGRB or H(z) data; (ii) gamma can be constrained quite well by all three data sets, contributing with approximate to 78% to the energy matter content; (iii) when a strong prior on (only) baryonic matter is assumed, the two parameters of the model are constrained successfully. (C) 2014 The Authors. Published by Elsevier B.V.

Hagiografía hispanolatina visigótica y medieval (s. VII-XII)

Coordinador de las actas: Maurilio Pérez González

Exploring new labelling strategies for boronated compounds: towards fast development and efficient assessment of BNCT drug candidates

208 p.