IR Spectra of Carbynoid Films Prepared by Dehydrofluorination of Polyvinylidene Fluoride

IR and X-ray photoelectron spectra of the products of chemical carbonization of polyvinylidene fluoride were recorded and discussed.     

Effectiveness of Space-Division Multiple-Access in MIMO Communication Systems with Parallel Data Transmission

We consider multiple-input multiple-output (MIMO) cellular communication systems with antenna arrays at both link ends and data transmission via parallel eigenchannels matched with a random spatial channel. We analyze the effectiveness of the space-division multiple-access (SDMA) method, which does not require estimation of signal-arrival directions and is based on orthogonalization of the parallel channels of all users. We obtained approximate analytical expressions for the mean ratio of the signal power to the noise power and the MIMO system capacity, which are derived for the case of Rayleigh fading of signals. Although the obtained formulas are much simpler than the exact ones, they ensure high accuracy for an arbitrary number of transmitting and receiving antennas and an arbitrary power of transmitter. Our results demonstrate the high effectiveness of the proposed SDMA method.     

Calculation of the vibronic transition moment when the geometries of the combining states of the molecules are significantly different

The concept of the adiabatic approximation is introduced from a few new standpoints, and the conditions are refined under which we can assume that the total energy of an electronic-vibrational (vibronic) state is the sum of the energies of the “electronic” and the “nuclear” problems and the wave function is represented as the product of the corresponding functions. An expression exactly corresponding to such an approximation is considered for the optical transition matrix element, and its individual terms are analyzed for any change in the geometric structure of the molecule upon optical excitation. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 290–293, May–June, 2006.     

Adiabatic theory of the vibronic states of the topological isomers of polyatomic molecules. Calculation of optimal conditions for optical stimulation of isomeric rearrangements

The problem of calculating the probability of optical transitions between the topological isomers of polyatomic molecules is considered. It is shown that the adiabatic approximation can be extended to this case. It is suggested that under certain conditions an “unoccupied” isomeric state can be populated or light-stimulated accumulation of one isomer can be achieved. This opens up prospects for designing molecular elements for computer memory. V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 6, pp. 994–1005, November–December, 1996. Translated by I. Izvekova     

Electronic structure of molecules of diphenyl bridge compounds

Using the CNDO/2 method, we have calculated the valence electron density distribution in molecules of diphenylamine and its 13 derivatives with the substituents COOH, NO₂, OCH₃ on the aromatic rings of ionized forms of some diaryl amines, and also 4-amino- and 4-amino-4-adnitro substituted compounds with bridge groups NH, O, S, CH₂, CH=CH and analogous diphenyl derivatives. We have shown that independently of the nature of the bridge group, the principle of uncoupling of the aromatic rings is basically retained. Strong long-range effects of the substitutents along the chain of chemical bonds are not apparent. We have calculated the electrostatic molecular potential of the indicated compounds. We have established correlations between the electrostatic molecular potential and the protonization constants, the oxidation-reduction potentials of diarylamines; and also between the electrostatic molecular potential and the reaction rate constant for acylation of primary bridged amines at the amino group.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 84–88, January–February, 1985.