Kinetics of the reaction HO2 + NO2(+M) = HO2NO2 using molecular modulation spectrometry

Rate constants for the reaction HO₂ + NO₂(+ M) = HO₂NO₂(+ M) have been obtained from direct observations of the HO₂ radical using the technique of molecular modulation ultraviolet spectrometry. HO₂ was generated by periodic photolysis of Cl₂ in the presence of excess H₂ and O₂, and k₁ was determined from the measured concentrations and lifetime of HO₂ with NO₂ present. k₁ increased with pressure in the range of 40–600 Torr, and a simple energy transfer model gave the following limiting second- and third-order rate constants at 283 K: k₁^∞ = 1.5 ± 0.5 × 10^?12 cm³/molec·sec and k₁^III = 2.5 ± 0.5 × 10^?31 cm⁶/molec·sec. The ultraviolet absorption spectrum of peroxynitric acid was also recorded in the range of 195–265 nm; it showed a broad feature with a maximum at 200 nm, σ_max = 4.4 × 10^?18 cm².     

The reaction of gold and dithizone

On thermodynamic grounds gold(III) and gold(I) are likely to oxidize dithizone rather than to form complexes. Conditions are described to obtain all the spectra previously ascribed to “gold dithizonate” both in a single system and separately. Oxidation products are responsible for several of the peaks, and it is unlikely that any of the species obtained is a gold dithizonate except possibly that giving the transitory peak at 490 nm. Analytical processes based on the reaction of gold and dithizone should be recognised as involving oxidation and treated with extreme caution.     

Hyperfine coupling constants in muonium adducts of the carbonyl bond

A representative series is studies of organic radicals formed by the effective addition of muonium to the carbonyl oxygen atom of aldehydes, ketones, esters and amides. Low values of the muonelectron hyperfine coupling are measured which are particularly sensitive to radical structure and dynamics. The systematics of these values are discussed in terms of the opposing contributions of conjugation and hyperconjugation.     

Affine extensions of supersymmetry: The finite case

We examine the graded Poincaré (GP) Lie algebra of supersymmetry with a view to constructing possible affine extensions of the algebra, i.e. extensions of the GP algebra which contain as a subalgebra the Lie algebra $\text{ga}\text{(4,}\text{R}\text{)}$. We restrict our attention in this paper to an examination of the finite extensions. We demonstrate explicitly that if we adjoin only a symmetric tensor generator to the GP algebra, then such a generator cannot generate all the deformations, in particular the shear, of the general affine group GA(4, $\text{R}$). Similarly, we show that adjoining the supersymmetry generator to $\text{ga}\text{(4,}\text{R}\text{)}$ cannot lead to closure of the resulting algebra, even in the trivial case. We further demonstrate that the GLA $\text{ga}\text{(}\text{4}\text{4}\text{,}\text{R}\text{)}$ does not contain the Lie algebra $\text{ga}\text{(4,}\text{R}\text{)}$ represented over the entire superspace upon which $\text{ga}\text{(}\text{4}\text{4}\text{,}\text{R}\text{)}$ is defined.     

Coupling rates and kinetics of arenediazonium cations with couplers utilized in the diazo reprographic process

Stoichiometric and, in most cases, absolute rates of coupling of a series of m- and p-substituted benzenediazonium ions with 2,3-dihydroxynaphthalene-6-sulfonate ion (1) have been determined (i) at pH 5.6 (when one OH group is partly monoionized) and (ii) at pH 9.9 (when one OH group is completely ionized and the second slightly so). The rates at both pH values correlate with the σ⁺ parameter (except for the most reactive ArN at pH 9.9) and the contributions of the two reactive forms of the coupler evaluated. Detailed pH dependences of the coupling rate of the p-chlorobenzenediazonium ion with (1) reveal a strong interaction between (1) and the borate ion, which strongly influences the coupling rate. Coupling rates have also been measured for both diazonium ions and couplers of importance in the diazo reprographic process.     

Microwave l-type resonance transitions of the v4 = 1 state in PF3: Detailed interactions and molecular structure

Observation of the direct l-type resonance transitions in the microwave spectrum of the v₄ = 1 state of PF₃ has been extended to J = 36. The w-type interaction, (Δl = 0, ΔK = 6), has been found from measurements on the “forbidden” Stark trasitions in the $\text{K}\text{= 3}$ series. Also in this series a close accidental degeneracy was found between J = 30, $\text{K}\text{= 3}$ and 0, leading to new zero-field “forbidden” transitions through the r-type interaction (Δl = 2, ΔK = ?1) and to the determination of the C rotational constant. Nine spectroscopic parameters were determined using 140 observed frequencies including two “forbidden” trasitions. After suitable correction the B and C constants were used to determine the r₀, r_z, and r_e structures for PF₃. The equilibrium structure is estimated to be P-F = 1.561 ± 0.001 Å and ∠FPF = 97.7 ± 0.2°.     

The misbehaviour of mercury(I) ions in cold-vapour atomic absorption spectrometry

The behaviour of mercury(I) ion in the cold-vapour atomic absorption spectrometry under nonreducing conditions is discussed. The signal obtained corresponds to about 35% of total mercury present. Under the same conditions, the same quantity of Hg²⁺ is found by dithizone spectrophotometry. Thus the cold-vapour signal is due entirely to disproportionation of mercury(I), which is not inhibited by chloride at mercury concentrations less than 120 μg l^?1. The cold-vapour signal si pH-dependent and at low hydrogen ion concentration, approaches the value expected from complete disproportionation.     

Some applications of bonded-phase high-performance liquid chromatography to the analysis of pharmaceutical formulations

Chromatographic procedures are presented for the determination of guaiphenesin, phenylephrine hydrochloride, phenylpropanolamine hydrochloridfe, pholcodine, methyl and propyl 4-hydroxybenzoates, and tyrothricin in some pharmaceutical products. An investigation of the contamination of lozenges with aspirin, paracetamol, phenacetin, prednisone and prednisolone is reported, together with the preparation of a novel bonded weak cation-exchange packing used.     

Charmed meson production in quark exchange model

Dynamical calculations of charmed meson production rates (via quark exchange) are presented, replacing previous kinematic predictions. Agreement with recent data on the ratio of production rates for different two-charmed-meson final states is reached, and other features of the calculated rates are also discussed.