A magnetic isotopic effect in the triplet sensitized photolysis of dibenzoyl peroxide

A ¹³C isotopic effect was detected in the triplet sensitized photolysis of dibenzoyl peroxide. Analysis of ¹³C NMR spectra shows that the amount of ¹³C in position 1 of phenyl benzoate, the cage product, increase by 23 ± 5% in comparison with natural abundance. The observed isotopic effect considerably exceeds the known ${}^{12}\text{C}{}^{13}\text{C}$ kinetic isotopic effects. This effect is believed to be magnetic in origin and is explained in terms of the dependence of the recombination probabilities of radical pairs in the cage on the electron-nuclear hyperfine interaction.     

The kinetic equations for isotopic exchange reactions allowing for the presence of an isotope effect

It is shown that the occasionally applied isotopic exchange, kinetic treatment of reactions is fundamentally flawed. This implies, quite wrongly, that the concentration of the products of the exchange reaction should rise linearly with time. Reactions in which there may be an appreciable isotope effect on the rate are carefully examined, resulting in equations appropriate to stable isotopes and to radioisotopes.     

Chemically induced magnetic isotope effect on the tin nuclei during the photolysis of (1-fluorenyl)trimethyltin

A magnetic isotope effect on the ¹¹⁷Sn and ¹¹⁹Sn nuclei, accompanied by the fractionation of magnetic and nonmagnetic tin isotopes, was observed during the photolysis of (9-fluorenyl)trimethyltin. The magnetic and nonmagnetic isotopes were accumulated, respectively, in the initial compound and a photolysis product (hexamethyldistannane).     

Seeking higher resolution and sensitivity for NMR of quadrupolar nuclei at ultrahigh magnetic fields

We report the acquisition of solid-state NMR spectra of quadrupolar nuclei obtained at very high magnetic fields (25 and 40 T), thus improving spectral sensitivity and resolution. For an example compound, the MAS spectrum obtained at 40 T is nearly free from the second-order quadrupolar broadening and can be interpreted quantitatively in a very simple manner.     

Infrared study and isotopic effect of magnesium hydroxide

The IR spectra of polycrystalline Mg(OH)₂ and Mg(OD)₂ are reported in the 4000–40 cm⁻¹ region. Band assignments were discussed on the basis of isotopic band shifts of the fundamental vibrations by combining the results of factor group analysis for D_3d³ crystal structure with the Teller–Redlich product rule for crystal vibrations. The band assignments proposed are different from the previous IR spectroscopic studies.     

The effect of magnetic field on conductive films

Conductive paints consisting of nickel powder (conductive material), solvent, and binder polymer were treated in a magnetic field. The efficiency of magnetic treatments on conductivity of coating films was evaluated. The effect of the following factors on conductivity of composite films by magnetic treatment was studied: metal powder concentration, magnetic flow density, time difference between film preparation and magnetic treatment, drying time of paint films, and effect of distance between terminals. Results showed that the volume resistivity of paint films treated magnetically was lower than that for untreated films at each nickel content. Magnetic treatment provided high conductivity even at low magnetic flow density, and conductivity increased with magnetic flow density.