On the acoustic wave attenuation in a turbulent medium

The equation for the mean acoustic field has been obtained for a random turbulent medium using the Green function approach. The correlation function was described by the Karman distribution with the index n=2 approximately≃11/6. Applying Bourret's approximation, the exact expression for the mass operator has been calculated analytically. The frequency dependence of the scattering coefficient of the mean field has been derived. Conditions of Cherenkov radiation are discussed.     

Model of geomagnetic field variations at the period range from 4 days until 3 years

Summary The field of the ring current in the magnetosphere is approximated by the spherical harmonicP ₁ ⁰ on the Earth’s surface. The authors analyse the choice of the coordinate system, where the spherical harmonicP ₁ ⁰ is determined, and test the technique of determining the pole position of the system by rotating the original axes in a set of observatories. The pole position was determined from the daily mean values (1969–1971 years) and the monthly mean values (1957–1978 years). The model ofP ₁ ⁰ source in this system was verified by the horizontal magnetic field variations in time range from 4 days to 3 years. The results allow us to use the model ofP ₁ ⁰ source for deep magnetovariation sounding in a coordinate system, which is close to the geomagnetic system at least for the analysed time intervals. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Vibrational-rotational behavior of diatomic heteronuclear molecular systems in intense laser pulses

The dynamics of diatomic heteronuclear molecules in the low-frequency intense laser pulses is studied by numerical solution of the time-dependent Schr?dinger equation and both rotational and vibrational degrees of freedom are taken into account. The interference stabilization against the dissociation process is found to take place in a strong field and is shown to result in trapping of population in different rotational-vibrational bound states due to efficient Raman V- and ??-type transitions. The interplay between the vibrational and rotational dynamics of a molecule is investigated. The dissociation suppression due to the interference mechanism and all its attributes are established in the case of multiphoton coupling between the initial state and dissociation continuum.     

Noncatalytic synthesis of carbon nanotubes by chemical vapor deposition

A new method is proposed to obtain uniform arrays of multiwall carbon nanotubes without catalysts. Nanotubes have been formed by carbon condensation from a hydrogen-methane gas mixture activated by a dc discharge. Structural and morphological investigations of the obtained material were performed by Raman spectroscopy, scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and electron energy loss spectroscopy. It is shown that the obtained nanotubes contain no impurities that could act as catalysts. Based on these experimental data, it is concluded that the nanotube synthesis under study is noncatalytic. Possible mechanisms of this synthesis are considered.