Vacuum ultraviolet 178.7 nm emission in sodium vapour under two-photon resonance excitation

We have observed a fixed wavelength emission at 178.7 nm in sodium vapour under 578.7 nm two-photon resonance excitation. The proposed non-linear wave mixing scheme is described by _{178.7 nm} = 2_L + _{465.7 nm}; where _178.7 is the 178.7 nm photon frequency, _L is the laser-photon frequency, and _465.7 is the 465.7 nm photon frequency. This 465.7 nm emission comes from another six-wave mixing process involving two hyper-electronic Raman scattering photons. The excitation spectrum of the 178.7 nm emission has a typical multiwave mixing pattern with a competing effect appearing at higher temperatures under two-photon resonance excitation. Numerical analysis indicates that this vacuum ultraviolet emission has a poor phase-match condition that will depress the emission intensity to a certain extent. This makes the observation more difficult compared with other reported four-wave mixing generated emissions. Fortunately, on the one hand, it is enhanced by quasi-auto-ionization resonance when the 3s–5s transition is coupled to the sodium continuum by a 330.2 nm photon. On the other hand, its wavelength sits so close to the sodium Cooper minimum that weak absorption will not suppress this vacuum ultraviolet emission further.     

Reaction-diffusion model for combustion with fuel consumption: II. Robin boundary conditions

A model, derived in a previous paper, for the reaction betweena gaseous oxidant and a solid porous fuel is analysed furtherfor general Robin boundary conditions. Numerical solutions areobtained and the effects of varying the dimensionless parameters,particularly the Frank-Kamenetskii parameter and the Lewisnumber L, are discussed in detail and compared with resultsobtained previously when Dirichlet boundary conditions are applied.Analytic solutions are obtained for the small-time developmentand for large values of . This latter solution shows the existenceof a propagating reaction-diffusion burning wave, and has featureswhich are qualitatively different to those derived earlier.     

A New Chemiluminescence Amplification Reaction for the Determination of HRP and Labelled HRP

A new chemiluminescence amplification reaction has been developed, which is on the coupling of the oxidation of Eosin by hydrogen peroxide under the catalysis of HRP at pH 3. 5 to the chemiluminescent reaction of luminol and hydrogen peroxide catalyzed by HRP at pH 10 to measure the activity of HRP and labelled-HRP. The detection limit of HRP is 10-10 g/mL. The lowest dilution ratio of HBsAb-HRP is 1 : 1. 8×102 and 1 : 106 for the direct method and coupled method respectively.     

N,N-二甲基甲酰胺中电沉积制备镁镍储氢合金

采用恒电位沉积法, 选用适宜的添加剂和络合剂, 成功地从N,N-二甲基甲酰胺(DMF)中沉积出致密的黑色Mg-Ni储氢合金膜. 并初步探讨了其共沉积机理. XRD显示沉积层中含有非晶态Mg-Ni相和微晶态Mg相. SEM图及相应能谱图分析表明合金颗粒以团聚状态存在, 合金成分不是很均匀. AAS分析表明沉积合金中Mg的原子摩尔分数达27.3%. LAND电池测试系统测得所镀合金膜的放电比容量最高为172.4 mAh/g.     

INTRAPARTICLE DIFFUSION EFFECTS IN FISCHER-TROPSCH SYNTHESIS Ⅰ. MODELING OF DIFFUSION AND REACTION

IntroductionCatal}ticrcactionsaffcctcdb}'diffosionaIlimitationincatal}'stporcshavcbccnextensive1}dcaltx`ithinlit.rat.rcll~5I.Scvcraltcchniqucsonthcspccialcase0fFischcr-Tropschs}'nthcsis(FTS)t\crcapplicdtocxplorcthebchaviorofthiscatal}ticrcactionundercxpcrimcntalandopcrationaIconditionsI3~5l.It`"ouldbeofvaluctoindicatchcrcthatthcseinvcstigationsx"ercmainl}'bascdonthesimplcstkineticsofthcfirstordcrinH2proposedbyAndersonl6]attheearIystages.However-thesetboents,striCtlyspeaking,areinvalidfor…     

氢化物发生-冷原子吸收光谱法测定化妆品中汞

介绍用氢化物发生-冷原子吸收光谱法在重铬酸钾-硝酸溶液存在下测定化妆品中汞的含量。方法空白值低、灵敏、准确、精密度好，特别适合于化妆品中汞的测定。