Redistribution of population among the higher levels of Na atoms in an H2-O2-Ar flame

A substantial fraction of the population of Na-atoms in an H₂-O₂-Ar flame is found to be distributed among the higher levels as a result of two-photon laser excitation, spontaneous emission and collisions with flame gas atoms and molecules. Several population inversions are observed. From the laser-excited level upwards, a partial Boltzmann equilibrium, corresponding to the flame temperature, has been found in some cases. Estimates of weighted average rate-constants for collisional energy transfer from groups of higher levels to the 3P-level are given. Some level-pairs appear to be strongly coupled to each other.     

Base-induced cycloaddition of N-(tosylmethyl)imino compounds to michael acceptors. Synthesis of 2,3,4-trisubstituted pyrroles

A series of N-(tosylmethyl)imino compounds [TosCH₂N?C(L)A] has been prepared, and applied to a new, base-induced, one-operational synthesis of otherwise more difficultly accessible 2,3,4-trisubstituted pyrroles from electron deficient olefins. This regiospecific process probably is an 1,3-anionic cycloaddition, combined with the elimination of sulfinic acid and a leaving group L. The group A is retained as the 2-substituent of the resulting pyrroles.     

A monitor for the specific determination of nickel carbonyl based on the chemiluminescence reaction with ozone and carbon monoxide

The chemiluminescence, measured at 500 nm, allows nickel carbonyl to be measured in the range 1 ppb to several ppm in combustion gases. Interferences from iron pentacarbonyl and nitrogen monoxide are eliminated by optical and spatial discrimination and by choice of the pressure in the reaction chamber.     

18F-Radiometric determination of the fluoride content of an anion exchange resin in the fluoride-form

The fluoride capacity of the Dowex 1-X4 anion exchange resin was measured by radiometric and elemental analysis. The capacity data obtained by the two methods showed good agreement.     

Two-atom model for the calculation of surface blocking in medium and high energy ion scattering

A two-atom blocking model has been developed to analyze surface blocking patterns recently obtained in medium energy ion scattering experiments. In the model the mean square thermal vibration amplitude of a surface atom can be used as a fitting parameter in comparison with experimental results. Anisotropic surface vibrations have been taken into account by assuming a non-spherical Gaussian probability distribution for the thermal displacement of the surface atom. In addition, some analytical expressions have been derived for the effective nuber of target atoms contributing to the yield of ions backscattered into a blocking direction.     

Hydrodynamic resistance of concentration polarization boundary layers in ultrafiltration

The influence of concentration polarization on the permeate flux in the ultrafiltration of aqueous Dextran T70 solutions can be described by (i) the osmotic pressure model and (ii) the boundary layer resistance model. In the latter model the hydrodynamic resistance of the non-gelled boundary layer is computed using permeability data of the Dextran molecules obtained by sedimentation experiments. It is shown both in theory and experiment that the two models are equivalent.