Theory of analytical curves in atomic fluorescence flame spectrometry

An explicit expression for the intensity of atomic resonance fluorescence as a function of atomic concentration in a flame is derived under certain idealized conditions. The expression is generally valid for a pure Doppler absorption line profile as well as for a combined Doppler and collisional broadened profile (Voigt profile) of the absorption line in the entire range of concentration values.The expression derived was used to calculate analytical curves for a number of different values of the ratio of collisional line width to Doppler width. The calculations were carried out for a single resonance line in the extreme cases of a very narrow exciting line source and a continuum radiation source, respectively.Furthermore, a method is given to determine the so called damping parameter “a” and the fluorescence yield factor p from the asymptotic behaviour of the analytical curves if the actual atomic flame content at the intersection point of the initial and final asymptote is calibrated.     

Some aspects of solution chemistry in liquid mixtures of inorganic salts with water

Experimental and theoretical investigations of some thermodynamic, transport and structural properties of very concentrated aqueous electrolyte solutions are reviewed. Attention is focussed on the range of concentrations between anhydrous molten salts and the hydrate melts. In this region, the hydration shells of the ions are incomplete, and ion-ion, ion-water, and water-water interactions must be considered. Extensions of the Debye-Huckel theory are not valid in this region, and models based on anhydrous molten salts may be useful.     

Experimental investigation of electrodeless discharge lamps as excitation sources for atomic fluorescence flame spectrometry

Experimental details of constructing electrodeless discharge tubes are given. The electrodeless discharge tubes are evaluated with respect to design and construction of an optimum source for use in atomic fluorescence flame spectrometry. By means of a statistical evaluation of data, it is shown that source intensities useful for the production of atomic fluorescence are directly related to lamp diameter, gas fill pressure, and form of element (metal or metal iodide) but are independent of the weight of metal or metal iodide introduced into the lamp. The optimum lamp diameter, gas fill pressure, and form of the element for production of analytically useful electrodeless discharge tubes and the spectral characteristics of the resonance lines produced by several electrodeless discharge tubes are given in tabular form. Problems encountered in the production of analytically useful sources for a number of elements are discussed. Resonant cavities and directional antennas as means of coupling microwave power into metal electrodeless discharge tubes are compared. For the studies presented here, the “A” type antenna with a quartz jacket for insulation around each source proved to give the greatest atomic fluorescence signals. Limits of detection for sixteen metals and analytical curves for fourteen metals excited by electrodeless discharge tubes in atomic fluorescence flame spectrometry are given to indicate the analytical utility.     

Surface wave propagation for linear viscoelastic solids

Experiments have been carried out to observe the surface waves produced on large blocks of polyethylene and polymethylmethacrylate (p.m.m.) when specimens of these materials have been subjected to surface impacts of steel balls or when small lead azide charges have been detonated on the free surfaces. It has been shown that if Poisson's ratio, v, is taken to be a real constant the shapes of surface waves can be calculated if the shape of the initial disturbance and the visco-elastic properties of the medium are known. It has further been shown that the complex nature of v results in only second-order effects for the materials used. It has consequently been found possible to forecast the shape of surface waves produced by the impact of steel balls. The agreement with experimentally observed shapes was found to be excellent for the p.m.m. specimen. The theoretical predictions were less accurate for the polyethylene specimen, but the predictions here agreed reasonably well with the experiments. It was not found possible to predict the surface waves produced by the explosive charges chiefly because of uncertainty of the shape of the initial disturbance. The experimental results did, however, show two distinct groups of waves, one travelling with the dilatational velocity and the other with a velocity close to that of the shear velocity. At short distances of travel these two groups overlapped.     

Stability trends of 1:1 and 2:1 dialkylmalonato rare-earth chelates

The step-formation constants of the 1 : 1 and 2 : 1 malonato, diethylmalonato, di-n-propylmalonato and di-n-butylmalonato rare-earth and yttrium chelates were determined at ionic strength 0·100 (KNO₃) at 25·0°C by a potentiometric method. The first and second ionization constants of the ligand acids were also measured.The trend of the first formation constants with cationic radius, observed with the lanthanide malonates, is followed in the case of the dialkylsubstituted rare-earth malonates. Stability increases with complexity of the substituents, although the dimethylmalonate ligand exhibits less affinity for rare-earth cations than malonate itself. The trends manifested by the second constants are less regular.A curious odd-even stability differential is apparent in these systems with the heavier rare earths (TbLu). The differential is apparent in both b₁, and b₁ and the cumulative effect in β₂ values is sufficient to cause reversal of the usual ion-exchange elution order in the case of the YbLu and the DyHo pairs when ammonium malonate buffer is the eluant on Dowex 50-X8.     

Some remarks about 5f → 6d and charge transfer transitions in uranium(IV) and plutonium(IV) complexes

Absorption spectra of uranium(IV) and plutonium(IV) complexes with chloride and oxygen-containing ligands in the range 220–400 nm have been determined. Absorption bands are ascribed to 5fⁿ → 5fⁿ⁻¹6d and charge transfer transitions. Relationships have been established between electro-negativity of the ligand and the number and position of 5fⁿ → 5fⁿ⁻¹6d and charge transfer transitions for the complexes.     

Free and forced oscillations of a dynamic system with “linear hysteretic damping” (non-linear theory)

Using a non-linear model of “linear hysteretic” damping proposed by Reid, a study is made of the free and forced oscillations of a dynamic system with “linear hysteretic” damping. Exact solutions are presented for both free and forced oscillations and comparison is made with approximate solutions obtained by the Krylov-Bogoliubov-Van der Pol method.