Topology of PbSnTe:In Layers Versus Indium Concentration

Technical Physics - The surface topology of epitaxial films of lead tin telluride solid solution (including with In additive, Pb1 – xSnxTe:In) has been examined using atomic force microscopy....     

Measurement of the W-->taunu production cross section in pp collisions at square root s=1.8 TeV

We report on a measurement of sigma(pp-->W+X)B(W-->taunu) in pp collisions at sqrt[s]=1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of 18 pb-1 of data collected with the D0 detector during 1994-1995. We find that sigma(pp-->W+X)B(W-->taunu)=2.22+/-0.09 (stat)+/-0. 10 (syst)+/-0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, gWtau/gWe, be unity. We find gWtau/gWe=0.980+/-0.031, in agreement with lepton universality.     

Acoustogyration diffraction of optical waves: case of SiO<Subscript>2</Subscript> and TeO<Subscript>2</Subscript> crystals

Interaction of acoustic and light waves with accounting for elastooptic and elastogyration effects is theoretically described. Collinear acoustogyration diffraction in quartz and paratellurite crystals is experimentally investigated and thoroughly analyzed. Piezogyration effect is experimentally studied for TeO₂ crystals. The acoustogyration efficiency and the acoustogyration figure of merit calculated for a number of crystals (GaAs, TeO₂ and SiO₂) are shown to be too small for experimental detection. On the other hand, we demonstrate that the light diffraction at periodical distribution of the imaginary part of dielectric permittivity related to the piezogyration effect should, in principle, be observed for the case of interaction of optical waves with enantiomorphous ferroelastic domain structure and in cholesteric liquid crystals.     

Transient absorption microscopy: advances in chemical imaging of photoinduced dynamics

This article reviews the state of the art of ultrafast transient absorption microscopy, discusses current experimental concepts and highlights future challenges. The advantages of transient absorption microscopy over other micro‐spectroscopic techniques are its high optical resolution combined with high temporal resolution as well as its ability to study non‐fluorescent and weakly fluorescent molecular species and to probe excited‐state processes. In conventional transient absorption spectroscopy the spectroscopic information usually presents a spatial average over the focal spot of the typically weakly focused probe beam. Transient absorption microscopy, however, enables investigations of the excited state dynamics in individual microscopic areas of a sample. Hence, the technique does not only yield detailed morphological information based on a label‐free molecular contrast, but also gives insight into the ultrafast morphology‐dependent photoinduced processes in heterogeneous samples. Different variations of transient absorption microscopy have found a number of applications ranging from material sciences to biology, which are discussed in this review together with different setup modifications and approaches towards transient absorption spectroscopy with spatial resolution below the diffraction limit.

     

Triterpene and steroid glycosides of the genusMelilotus and their genins IV. Trillin and dioscin from the seeds ofMelilotus tauricus

Two steroid glycosides belonging to the spirostan series — trillin and dioscin — have been isolated from the seeds of the plantMelilotus tauricus (Bieb.) Ser. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 770–772, November–December, 1994.     

Coherent Raman scattering in molecular hydrogen in a dc electric field

The polarization properties of light in coherent Raman scattering in molecular hydrogen in a dc electric field are investigated. A nonlinear polarization-optical method of determining the absolute magnitude and orientation of the dc electric field is proposed and realized. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 6, 371–375 (25 September 1999)     

Influence of the size effect on the electrical conductivity of partially stabilized zirconia

The volume component of the electrical conductivity of bulk ceramics of the partially stabilized zirconia (ZrO₂)_0.94(Y₂O₃)_0.05(Al₂O₃)_0.01 is found to increase by a factor of 1.7 with the grain size decreasing from 600–800 to 200–300 nm. The observed effect is explained by the action of the pressure produced by surface tension forces, which shifts equilibrium toward the point of the polymorphic transition to the cubic phase.