Exploitation of gradient techniques in flow injection analysis

Summary Founded on the key role of dispersion, controlled in space and time, the FIA gradient techniques are based on the feasibility of identifying and selecting reproducibly suitable sections of the time/concentration matrix represented by the dispersed sample zone and exploiting the specific concentrations at these points for analytical purposes. The characteristics and common theme of these gradient procedures — comprising gradient dilution and calibration, stopped flow reaction rate measurement, titrations, gradient scanning, and systems associated with simultaneous injection of two zones which completely or partially overlap thereby permitting the execution of selectivity studies and standard addition procedures — are briefly reviewed.

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Ausnutzung von Gradientenverfahren bei der Fließinjektionsanalyse

     

Production of high transverse momentum particles in p-p-collisions in the central region at the CERN ISR

The inclusive production al all charged particles of transverse momentum p_T between 1.5 and 4.4 GeV/c at centre of mass angles 90° and 59.4° from p-p-collisions with √s = 44 and 53 GeV has been measured. No strong energy dependence is observed for these transverse momenta.     

Energy levels in even actinide isotopes from (t,p) reactions

Energy levels in^{232, 234}Th,^{236, 238, 240}U and in²⁵⁰Cm have been measured using the (t, p) reaction. Angular distributions were obtained for the^{234, 238}U targets and evidence for second order effects in the direct reaction mechanism was found.     

Degrees and independent sets of hypergraphs

Lower bounds for the cardinality of maximal and maximum independent sets in hypergraphs are obtained from two different definitions of the degrees of the vertices.     

Internal conversion coefficients and penetration effect for the 279 keV transition in203Tl

The internal conversion process of theM1+E 2 mixed 279 keVγ-ray transition in the decay of²⁰³Hg has been reinvestigated. The emission rate of theK-shell internal conversion electrons was determined with an electron X-ray coincidence measurement using a magneticΒ-spectrometer and a Si(Li) detector of high energy resolution. Conversion electron ratios were obtained from electron spectra recorded as a function of momentum. The disintegration rate has been taken from measurements with a calibrated NaI(Tl)γ-ray spectrometer. Following results have been deduced: α=0.2279±0.0024, α _K =0.1653±0.0017, α _L =0.0475±0.0013,K/(L+M+?)=2.64±0.03,K/L=3.48±0.12,L/(M+N+ ?)=3.14±0.12. On the basis of the experimental results on theK-shell internal conversion coefficient,α _k , and the conversion ratioK/(L+M+?) the penetration effect on the internal conversion of theM1 part and the mixing ratio,δ ², of the 279 keVγ-ray transition in²⁰³Tl have been studied. Calculations were made using Hager and Seltzer's formalism and their theoretical internal conversion coefficients. The results are consistent with a mixing ratio ofδ ²=1.32±0.11 and a penetration parameter ofλ=6.8 ±0.8.     

Picosecond resonant two-photon ionization of cold sodium clusters

Large sodium clusters, up ton=21, generated by a low-temperature modification of the laser ablation gas jet source were ionized with two photons of visible radiation from an amplified picosecond dye-laser system.