Thermalization time of thin metal film heated by short pulse laser

Based on the hyperbolic two-step heat conduction model, using the Laplace transform and numerical inverse transform method (Riemann-sum approximation method), the thermal behaviour of thin metal films has been studied during femtosecond pulse laser heating. Also the thermalization time, which is the time for the electron gas and solid lattice to reach thermal balance, has been studied in detail. The values of thermalization time for silver (Ag), gold (Au), copper (Cu) and lead (Pb) are obtained. The effects of material parameters of the thin metal film on the thermalization time are considered for the four kinds of metals by changing one of the parameters and regarding the other parameters as constant. For a typical metal material, the order of the thermalization time is of the order of hundreds of picoseconds. The thermalization time decays exponentially with the increase of phonon－electron coupling factor or electron gas thermal conductivity, and it increases linearly with the increase of the ratio of lattice heat capacity to electron gas heat capacity. However, the relaxation time of the electron gas has very little effect on the thermalization time.     

新型双二元席夫碱的合成与谱学性质

新型双二元席夫碱的合成与谱学性质;双二元席夫碱化合物     

Acknowledgment

l-Nitroso-2-naphthol(HA)isahighlyselectivereagentforthespectrophotometricdeterminationofCo(III)i.Raoetal.havestUdiedtheequilibriumextractionbehaviorofmixedligandcomplexesoftrivalentSm,EuandDyionswithl-nitroso-2-naPhtholandtrioctylphosphineoxide',Dyrssenetal.haveexaminedthecomplexformationofTh(IV)withl-nitroso-2-naPhtholand2-nitroso-l-naPhthol',however,thereisnoreportfortheextractionmechanismoflanthanidesbeingattemptedwiththisreagent.Inrecentyears,ourlabhasdonesomeworkonthesolid-liquidext…     

镧系元素的中性络合固-液萃取分离研究(Ⅱ)--TOPO-NaClO4-石蜡体系

本文以正三辛基氧膦为萃取剂,以熔融石蜡为稀释剂,研究了ＨＣｌＯ４－ＮａＣｌＯ４介质中Ｌａ＾３＋、Ｎｄ＾３＋、Ｓｍ＾３＋、Ｄｙ＾３＋Ｙｂ＾３＋的固－－液萃取行为及萃取反应热力学性能。斜率比法给出萃合物组成为Ｌｎ（ＴＯＰＯ）２（ＯＨ）（ＣｌＯ４）２。测定了萃取反应势力学参数、平衡常数及半萃取ｐＨ值。     

M调变六铝酸盐MNiAl_(11)O_(19-δ)的制备和对CO_2重整甲烷制合成气的催化性能(英文)

通过Ｍ的调变作用,制备了一系列六铝酸盐ＭＮｉＡｌ_（１１）Ｏ_（１９－δ）（Ｍ＝Ｃａ、Ｓｒ和Ｂａ）作为二氧化碳重整甲烷制合成气反应新催化剂,探索了它们的结构和催化性能。结果表明,这些催化剂在高温下对二氧化碳重整甲烷制合成气反应都表现出良好的催化活性和稳定性,在７８０℃下反应２小时,甲烷和一氧化碳转化率均在９３．４％和９１．２％以上,没有发现活性组分Ｎｉ的高温烧结和催化剂失活。同时,不同Ｍ调变对六铅酸盐催化剂的催化活性有不同影响。     

离子交换/8-羟基喹啉荧光法分别测定天然水中的无机和有机单核铝

采用离子交换／氯仿萃取－８－羟基喹啉荧光法（８－Ｏｘ－ＣＦ－ＥＦ）分别测定了天然水样中的无机和有机单核铝。与Ｄｒｉｓｃｏｌｌ建立的铝形态区分法进行了比较,结果一致,本法优点是：可以直接测定水中的无机单核铝,减少了实验误差。     

微型Nd：YVO4激光器在碘分子调制转移光谱中的应用

以半导体激光器抽运微型Nd:YVO4倍频激光器为光源获得碘分子在532nm处的光外差调制转移光谱信号,并对获取最佳稳频信号的实验条件进行了讨论。     

本征不对称光纤法布里-珀罗干涉仪的理论模型

应用光学和数学理论导出本征不对称光纤法布里－珀罗干涉仪中反射光与透射光的数学模型及低反射率法布里－珀罗干涉腔长度的变化与干涉光光强的数学模型,半指出当ｒ１１＝ｔ１ｔ１ｒ２＝ｒ,且ｔ１ｔ１＝１－ｒ１＾２≈２。则法布里－珀罗腔反射光间的干涉近似为两束等幅光的干涉;文章还给出了光电转换器输出与法布里－珠罗干涉腔长度变化的数学模型。这些模型为不对称光纤法布里－珀罗干涉仪的使用提供理论依据。     

Gurtin变分原理在矩形板动力初值问题中的应用

结构动力分析是工程设计中的重要组成部分,传统动力分析方法并不能全面反映动力初值特征,而Ｇｕｒｔｉｎ变分原理则被认为是目前唯一能全面反映动力初值特征的变分原理。本文基于位移型Ｇｕｒｔｉｎ变分原理,对空间和时间同时离散,建立了一种求解板的动力初值问题的时空有限元法,并对两种边界情况板的振动问题进行了编程计算,计算结果表明时空元法精确度很高且稳定收敛。     

Hollow Metal–Organic-Framework-Mediated In Situ Architecture of Copper Dendrites for Enhanced CO2 Electroreduction

Electrocatalytic reduction of CO₂ to a single product at high current densities and efficiencies remains a challenge. However, the conventional electrode preparation methods, such as drop-casting, usually suffer from low intrinsic activity. Herein, we report a synthesis strategy for preparing heterogeneous electrocatalyst composed of 3D hierarchical Cu dendrites that derived from an in situ electrosynthesized hollow copper metal–organic framework (MOF), for which the preparation of the Cu-MOF film took only 5 min. The synthesis strategy preferentially exposes active sites, which favor's the reduction of CO₂ to formate. The current density could be as high as 102.1 mA cm⁻² with a selectivity of 98.2 % in ionic-liquid-based electrolyte and a commonly used H-type cell.