Structural differentiation of isomeric N-oxides

The recently reported photochemical isomerization of 1-(2-pyridyl)benzotriazole 3-oxide to the 2-oxide created a need for a method of distinguishing between the structural isomers. Nmr experiments using Eu(fod)₃ established the position of the oxygen atoms and also yielded convincing evidence regarding attachment of the lanthanide shift reagent to these multi-functional compounds. Double irradiation experiments were used to resolve the structural problem while shift gradient considerations led to probable sites of coordination.     

Very high frequency radiowave scattering by a disturbed sea surface Part II: Scattering from an actual sea surface

A two-scale model of rough surfaces is considered which permits theoretical interpretation of the features of very high frequency (VHF) scattering from such surfaces (say, from a sea surface). The scattering surface is assumed to be a superposition of small-scale ripple and large waves (swell). Reflection from the latter may he considered by the Kirchhoff approximation. The spatial spectrum of corrugations is taken into consideration; the calculations based on this model help to give an explanation of the behavior of the scattered intensity as a function of the angle of incidencepsi, and to establish which factors affect this dependence at various values ofpsi- Theoretically predicted dependence of the scattered intensity upon radio wavelengthlambda, depolarization of the scattered signal, and other features of the scattered radiation are in good agreement with the experimental data obtained from direct measurements. Frequency spectra of the backscattered signal were also investigated (experimental measurements were carried out at wavelengths 3.2 cm, 10 cm, 50 cm, 1.5 m, and 4 m). Observed shifts of the central frequency agree with results of other authors (for the range oflambda = 3cm to 200 m). The measured values of the spectrum width appeared approximately twice those theoretically calculated. This may be explained by the influence of dissipative processes and of fluctuations of the skin-deep layer drift velocities. Space correlation of the backscattered signal was also investigated (both theoretically and experimentally). 50 percent decorrelation occurs at distances compared with dimensions of a wave slope.     

A sum rule for the rotational band of a molecule with C3V symmetry

A sum rule is derived for the integrated intensity of the rotational band of a symmetric top molecule with C_3V symmetry, simply by direct summation over all the rotational transitions.     

Radiophysical investigations of sea roughness (radiooceanography) at the Ukrainian Academy of Sciences

Experiments on the scattering of radio waves in the range 200 m to 3 cm from a rough sea surface are described. Amplitude, frequency, and space-time characteristics of scattered radio signals at different states of the sea surface are presented. It is shown that the problem of the short and medium wave scattering from the sea can be solved by the perturbance method. In this case the mechanism of scattering is of "resonant" character. The intensity of the backscatter signals is proportional to the density of the spatial spectrum on the half-length of the radio waves. The high frequency radio wave scattering is well described by a two-scale model of the scattering surface, "ripple on the large wave." The intensity of scattered radio signals is also proportional to the spectrum density of "ripples" whose length is approximately equal to half a radio wave. The effect of the large waves is to modulate the amplitude of a scattered radio signal and to broaden its frequency spectrum. Methods of solution of the reverse problem were considered. This allowed determination of parameters of sea roughness by characteristics of scattered radio signals. The principles of design of the corresponding equipment are described.