Drift of gases induced by nonmonochromatic light

The phenomenon of light-induced drift of gases influenced by a nonmonochromatic light with different spectral properties is under consideration. The dependence of the drift velocity on the spectrum shape, bandwidth, detunings and light intensity is studied. The largest drift velocity is found to be obtained at the bandwidth of the spectrum being of the order of the Doppler atomic transition width, and when the wings of the spectrum drop rapidly. It is shown that nonmonochromatic light of the same intensity as a monochromatic one allows to reach a much larger drift velocity. Principal possibilities to obtain supersonic light-induced drift velocities are shown.     

Optical chaos in multiple degenerate four-wave mixing

Spatial evolution has been studied of an ensemble of equal-frequency light waves involved in several four-wave mixing processes under linear photoabsorption. It is shown that this system may exhibit spatial chaos caused by competition of optical mixing processes with strong energy exchange between the waves. For pulsed radiation, the temporal envelopes of interacting waves undergo modulations which may also be of chaotic character. Also discussed are possible variants of identifying chaos in systems of interacting light waves experimentally and the role of accompanying photoprocesses (photoabsorption, self-action of radiation).     

Effect of quartz concentration and dispersity on the physico-mechanical properties of perchlorovinyl film

The structure of perchlorovinyl film is not affected by the addition of finely ground quartz. The modulus of elasticity and coefficient of thermal expansion of the film change additively with increase in filler concentration and do not depend on filler dispersity. The filler reduces the strength of the film and the elongation at break.Institute of Physical Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1023–1027, November–December, 1969.     

Atom-density distribution in a metal vapor cell studied by third-harmonic generation

The density distribution of Cs atoms in a metal-vapor cell designed for nonlinear optical and spectroscopic measurements has been investigated by the THG technique. For high heater powers the desnity-distribution function was found to display a dip in the central part of the cell. Explanation of the phenomenon and criteria to eliminate it are proposed.     

On two-photon excited gas drift under a train of ultrashort laser pulses

A theoretical analysis has been carried out of the light-induced drift (LID) of gases which is two-photon-excited by a mode-locked laser radiation. The mode-locking is shown to ensure a 10²–10³ times increase of the LID-effect estimated under typical experimental conditions.     

Lagrangian turbulence in nonstationary 2-D flows

Lagrangian particle transport in nonstationary 2-D flows is studied both analytically and numerically. Analytic expressions for the diffusion coefficients are obtained for the adiabatic regime. Numerical estimates of the diffusion coefficients are found to agree with the theoretical results.