Nonlinear induced reflection of light waves in semiconductors

A scheme of nonlinear optical four-wave mixing of two counterpropagating laser beams on the surface of a semiconductor is proposed and analyzed. It is shown that the density modulation of the electron-hole plasma current carriers in the light-induced grating manifests itself in the probe beam depolarization signal after the reflection from the surface, which is sensitive to the state of the surface and presence of complex molecules on it.     

Eleuthesides and their analogs: XI. Final stage of the synthesis of sarcodictyin A analog with 14-methylcyclohex-12-ene ring A

Proceeding from derivatives of levoglucosenone and piperilene Diels–Alder adduct a total chemical synthesis was completed of sarcodictyin A analog possessing a 14-methylcyclohex-12-ene ring А. A practical version was developed of N(τ)-methylation of urocanic acid.     

Change in the spectral parameters of a laser plasma on a change to two-pulse irradiation of a dielectric in air

Translated from Zhurnal Prlkladnoi Spektroskopii, Vol. 51, No. 4, pp. 564–571, October, 1989.     

Spectroscopy of four-wave mixing on a semiconductor surface

Spectra of scattering on surfaces of semiconductors are obtained using the four-wave scheme of laser beam interaction. A considerable difference in the shape of the scattered signal is observed when the circular polarization vector of the pump beam rotates in two opposite directions.     

Concept of the Superpositional State in the Problem of Molecular Mesomorphism: An Analytical Review

It is shown that plastic and liquid crystals differ exclusively in characteristics of topologic order and are peculiar structural forms of more general superpositional state. On the basis of the generalization of the concept of a paracrystal a diagram of structural states is constructed allowing to classify partially ordered phases over the degree of destruction of long-range translational and orientational order.     

Brillouin scattering in a medium with inhomogeneous distribution of the interatomic interaction potential

Stationary Brillouin scattering in an elastic medium with spatially inhomogeneous distribution of the interatomic interaction potential is considered in the one-dimensional approximation. Frequency dependence of the optical signal on the acoustic inhomogeneity parameters is obtained. The experiments were carried out in distilled water and aqueous solution of the α-chymotrypsin protein using spectroscopy of coherent four-photon light scattering in the range 0 to 1 cm⁻¹ with the resolution of 0.06 cm⁻¹. Several Brillouin resonances corresponding to different types of microinclusions were observed in both media.     

Remote sensing of Arctic Fjords by Raman lidar: Heat transfer screening by layer of glacier’s relict water

West Spitsbergen fjords have been probed (on shipboard) by a compact Raman lidar (Wave Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences), based on a pulsed diode-pumped Nd³⁺:YVO₄ laser with frequency doubling, in August, 2011. The evolution of lidar signal spectra (Raman, fluorescence, and elastic scattering) when approaching the Paulabreen glacier of the Rinders Fjord has been measured. A new phenomenon was discovered: the formation of an immiscible layer of relict thaw water from the glacier on the sea surface. An increase in the layer thickness (to 5?C10 cm near the glacier) was accompanied by a decrease in the layer temperature (which was determined by measuring the distortion of the OH Raman band) and the content of phytoplankton and dissolved organic matter to zero, with a simultaneous increase in the Rayleigh scattering amplitude and a change in the surface color from blue to gray. Smoothing of the rippled sea surface (covered by relict water) at the border of the wake trace (which it rolled down from) was observed for the first time, as far as we know. The mechanism of the formation of a supercooled (t ? 0°C) layer and screening the heat diffusion, which reduces the contribution of the relatively warm sea water (??3°C) to the thermal balance of Arctic and global climate, is discussed.     

Low frequency four-wave mixing spectroscopy of biopolymer hydration layers in aqueous solutions

Four-wave mixing (FWM) spectroscopy has been applied to detection of H₂O₂ molecules rotational resonances in both DNA and denatured DNA aqueous solutions in the range ±100 cm⁻¹. A considerable growth of rotational lines intensity of H₂O and H₂O₂ has been observed in comparison with distilled water. This fact was interpreted as an exhibition of specific property of a hydration layer formation at DNA/water and denatured DNA/water interfaces. The fitting of four-wave mixing spectra shows the increasing of the H₂O₂ rotational line’s amplitude by a factor of ∼3 in DNA solutions due to denaturizing. The shifting of FWM Brillouin resonances in opposite way in protein solution and SWNT (single wall carbon nanotube) suspension to comparison with water was observed and discussed.     

Changes in the Raman spectrum of OH stretching vibrations of water in an ultrasonic cavitation field

A modification of the local structure of molecular aggregates in liquid water subjected to the action of an ultrasonic cavitation field is found. This modification is detected by the shift of the center of the Raman band contour of the OH stretching vibrations. It was also found that both the structure and the growth rate of lysozyme crystals grown in redistilled Milli-Q water and in water subjected to cavitation treatment differ considerably from each other.