The determination of lead and nickel by atomic-absorption spectrometry with a flameless wire loop atomizer

In an extension of studies of flameless atomizers for atomic-absorption spectrometry, an electrically heated tungsten-rhenium alloy wire loop was examined. Reduction of metallic salts to ground-state metal atoms was accomplished with the high temperature produced by the loop. Lead and nickel were investigated. Experimental parameters such as wavelength, slit width, atomization temperature and sheathing gas flow rate were optimized. Absolute detection limits of 6.6·10^?10 and 1.2·10^?10, and absolute sensitivities of 7·10^?10 and 8·10^?11 g of lead, were established for unenclosed and enclosed cells, respectively. The interferences of twenty cations and sixteen anions were studied; foreign cations generally enhanced the lead absorption by retarding its vaporization, allowing the slow detection system to respond more efficiently. Nickel was investigated as a representative less volatile metal; an absolute detection limit of 1.6·10^?9 and an absolute sensitivity of 9·10^?10 g of nickel were established.     

INDO-MO calculations of hyperfine splitting constants for pyridine anions

INDO-MO Calculations have been carried out on the anions of a variety of pyridine derivatives for which e.s.r. data have recently become available. The method gives reasonable results for proton hyperfine splitting constants but calculated nitrogen splitting constants are considerably larger than the experimental values. Some -only calculations are included for the pyridine anion. All methods overestimate the spin density at the nitrogen atom. The orbital populations and excess charges for the pyridine molecule are not in agreement with those of an ab initio calculation.     

Binding energy of lithium halide molecules

A semi-empirical open shell model of sigma bonded systems has been employed to calculate the binding energies for diatomic lithium halides. The repulsion between the atomic cores is taken as the Coulomb repulsion term $\text{1}\text{R}{}_{12}$ modified by the presence of electronic cores. This modification has been estimated from the repulsion term in the Rittner potential function. The agreement with the experimental values is quite satisfactory but the extension of the same method to alkali hydrides results in gross discrepancies. The results are discussed in the light of other results.     

Reactions of Titanium Alkoxides with N-Methylaminoalcohols

N-methylaminoalkoxides of titanium of the type Ti(OR)_4?n(O · CHR′ · CH₂ · NR″R?)_n where R = Et and Pr¹; n = 1–4; and R′ = R″ = H, R? = Me; R′ = H, R″ = R? = Me; R′ = R″ = R? = Me, synthesized by the reactions of titanium alkoxides with aminoalcohols, show interesting variations in their properties like physical state, volatility and molecular complexity. I.r. and p.m.r. spectra of these derivatives have been recorded. A few interchange reactions with methanol and tert-butanol have also been carried out. These aminoalkoxides get cleaved with acetyl chloride and undergo insertion reactions with phenylisocyanate, thus providing the first examples of insertion reactions in such derivatives.     

Polymerization and copolymerization of methacrylic esters derived from glycidyl methacrylate

Copolymerization of methacrylic esters derived from glycidyl methacrylate and nucleophiles with styrene was carried out. The monomer reactivity ratios of these methacrylic esters were varied with the alkoxy groups of the esters and the solvent used.     

Electrothermal atomic-absorption spectrometry of arsenic and its application to environmental samples

Electrothermal atomization of arsenic with a metal micro-tube atomizer has been studied. Thiourea and thionalide were found to give effective atomization of arsenic. A method involving extraction of the thionalide complex for determining traces of arsenic in water and soil is described.     

Simultaneous observation of coherent and incoherent resonant re-emission in the condensed phase

We report simultaneous observation of coherent resonance Raman scattering and incoherently broadened resonance fluorescence following excitation of cytochrome c in the α(0, 0) region. The influence of incoherent broadening processes on resonance Raman scattering experiments is considered.     

On-column injection onto capillary columns. Part 2: Study of sampling conditions; practical recommendations

During one year continuous use of on-column injection, the typical advantages described in our first report have fully been confirmed. In addition the analysis of large sample volumes has proved promising. Only minor modifications have been applied to the on-column injector device. Broad evidence has been gathered showing that full separation efficiency of the capillary columns after on-column injection is attained only when cold trapping or the solvent effect, as band shortening mechanisms, are working- While, under the conditions of on-column injection, cold trapping is less efficient than with other injection techniques, the opposite holds true for the solvent effect. Compared with splitless injection, the danger of excessive solvent condensation on the column is increased. A working rule is presented for establishing the optimal chromatographic conditions for handling large sample volumes while ensuring full separation efficiency yet avoiding harm to the column.     

Vibrationally resolved photoelectron angular distributions for H2

The photoelectron asymmetry parameter, β, is reported for individual vibrational levels of H₂⁺(X²Σ_g⁺) formed by photoionization of H₂(X¹Σ_g⁺) at wavelengths of 736, 584, 461 and 304 Å. At 584 Å, β, exhibits a monotonic increase with vibrational quantum number (decreasing photoelectron kinetic energy) confirming the trend predicted by Itikawa.