Recently efficient room temperature lasing material for this IR range has been demonstrated in II... more Recently efficient room temperature lasing material for this IR range has been demonstrated in II-VI semiconductors doped with transition metals. These dopants incorporated into CdSe substitute metallic atoms and create deep levels in the band gap. The room temperature mid-infrared absorption in CdSe:Cr is observed due to the intracenter transtion 5T2-->5E of Cr2+ ions. These tetrahedrally-coordinated ions are especially attractive
... Q; '(k = 0) is not defined, but ui(k = 0) is equal to the average of ui(x) over the real... more ... Q; '(k = 0) is not defined, but ui(k = 0) is equal to the average of ui(x) over the real space, which vanishes due to symmetry. ... A previous work (Shneck, Rokhlin and Dariel 1981) served as a guide in a trial and error procedure, aimed at finding these constants. ...
ABSTRACTThin films of PbTe were deposited on Si (111) wafers and glass substrates at a constant p... more ABSTRACTThin films of PbTe were deposited on Si (111) wafers and glass substrates at a constant power for different times and at a constant time at various power levels. In some cases substrate heating to a temperature of ∼673K was performed during sputtering. Structural analysis by Xray diffraction (XRD) and high-resolution electron microscopy (HRTEM) were performed. The composition of the PbTe film was evaluated by Auger depth profile. At an appropriate combination of power and deposition time only (200) and its higher order peaks were observed in the PbTe film. It is expected that it is feasible to obtain epitaxial PbTe film by RF magnetron sputtering.
Polycrystalline thin films of lead sulphide were deposited on glass substrates by the hot wall te... more Polycrystalline thin films of lead sulphide were deposited on glass substrates by the hot wall technique. The grain size varied from 100 to 500 A by varying the growth rate and the substrate temperature. The grain boundaries are assumed to influence the optoelectronic properties of polycrystalline films by generating potential energy relieves, estimated to reach 0.1 eV. We investigated the influence of the barrier height by introducing impurity atmospheres into the grain boundaries. Oxygen and indium were introduced into the films by diffusion from a gas phase. Conductivity was measured in the 80-300 K range. It rises with increasing temperature in oxygen doped films, indicating that conductivity is a thermal activation process. In the same time the conductivity of In doped PbS films decreases with temperature like in PbS single crystals. Photoconductivity was observed in films annealed in oxygen, which was significant up to room temperature. Carrier lifetime was found to decrease w...
ABSTRACT The present paper is concerned with the solution of the problem of a finite coherent pre... more ABSTRACT The present paper is concerned with the solution of the problem of a finite coherent precipitate in an elastic isotropic and homogeneous layer. The positive hydrostatic pressure in the matrix near a dilating precipitate is deduced by comparing the displacements in a layer to those in an infinite solid. The positive hydrostatic pressure gives rise to an attractive elastic interaction between like particles that increases monotonically with decreasing interparticle distance. The attractive interaction is maximal when the particles become of equal size and it increases as they grow closer to the free surfaces. The correlations that result from the elastic interaction in the thin layers generate a tendency toward clustering of equal-sized particles. The self-energy of an isolated precipitate decreases rapidly as it grows closer to the free surfaces favoring, at the advanced stages of the precipitation, precipitate coalescence rather than clustering.
Concepts and Challenges in the Biophysics of Hearing - Proceedings of the 10th International Workshop on the Mechanics of Hearing, 2009
255 THE ANISOTROPY OF THE TECTORIAL MEMBRANE GUIDES STEREOCILIA DEFLECTION R. GUETA1, D. BARLAM2,... more 255 THE ANISOTROPY OF THE TECTORIAL MEMBRANE GUIDES STEREOCILIA DEFLECTION R. GUETA1, D. BARLAM2, RZ SHNECK3, I. ROUSSO1 1 Dept. of Structural Biology, Weizmann Institute of Science, Israel 2 Mechanical Engineering, Ben-Gurion University oftheNegev, ...
ABSTRACT Two ways to calculate the elastic interaction between quantum dots (QDs) in the framewor... more ABSTRACT Two ways to calculate the elastic interaction between quantum dots (QDs) in the framework of linear elasticity are introduced and shown to vary in a similar way as the hydrostatic pressure. It is shown that the hydrostatic stress is the potential for the elastic interaction energy. The approach was used to estimate quantitatively the interaction energy between QDs in material systems that may form vertical order, anticorrelated order and FCC superlattice. The vertical interaction energy is very small compared with the thermal energy, nevertheless it is just enough to induce vertical ordering of QDs between layers. The attractive lateral interaction is an order of magnitude smaller than the vertical interaction, therefore ordering of multilatered QDs is made possible only by the vertical interactions. Several experimental observations are explained based on this understanding. The lateral interactions are small due to the small stresses set in the substrate after relief of the misfit strains in the free space. The vertical interactions are larger due to the large tensile stresses set up in the thin layer of matrix that separates an embedded QD from the free surface.
Proceedings of the National Academy of Sciences, 2006
The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the coc... more The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the cochlea. Its strategic location, together with the results of recent TM-specific mutation studies, suggests that it has an important role in the mechanism by which the cochlea transduces mechanical energy into neural excitation. A detailed characterization of TM mechanical properties is fundamental to understanding its role in cochlear mechanics. In this work, the mechanical properties of the TM are characterized in the radial and longitudinal directions using nano- and microindentation experiments conducted by using atomic force spectroscopy. We find that the stiffness in the main body region and in the spiral limbus attachment zone does not change significantly along the length of the cochlea. The main body of the TM is the softest region, whereas the spiral limbus attachment zone is stiffer, with the two areas having averaged Young's modulus values of 37 ± 3 and 135 ± 14 kPa, respect...
Modelling and Simulation in Materials Science and Engineering, 1995
... In the second problem, we calculate the stresses in a solid plate of thickness 2h, acting on ... more ... In the second problem, we calculate the stresses in a solid plate of thickness 2h, acting on its two surfaces z = h and z = -h, by tractions of the same magnitudes as calculated above but of opposite signs, T: = -U;; r: = -U; and q* = -uz (figure I@)). The superposition of the two ...
Recently efficient room temperature lasing material for this IR range has been demonstrated in II... more Recently efficient room temperature lasing material for this IR range has been demonstrated in II-VI semiconductors doped with transition metals. These dopants incorporated into CdSe substitute metallic atoms and create deep levels in the band gap. The room temperature mid-infrared absorption in CdSe:Cr is observed due to the intracenter transtion 5T2-->5E of Cr2+ ions. These tetrahedrally-coordinated ions are especially attractive
... Q; '(k = 0) is not defined, but ui(k = 0) is equal to the average of ui(x) over the real... more ... Q; '(k = 0) is not defined, but ui(k = 0) is equal to the average of ui(x) over the real space, which vanishes due to symmetry. ... A previous work (Shneck, Rokhlin and Dariel 1981) served as a guide in a trial and error procedure, aimed at finding these constants. ...
ABSTRACTThin films of PbTe were deposited on Si (111) wafers and glass substrates at a constant p... more ABSTRACTThin films of PbTe were deposited on Si (111) wafers and glass substrates at a constant power for different times and at a constant time at various power levels. In some cases substrate heating to a temperature of ∼673K was performed during sputtering. Structural analysis by Xray diffraction (XRD) and high-resolution electron microscopy (HRTEM) were performed. The composition of the PbTe film was evaluated by Auger depth profile. At an appropriate combination of power and deposition time only (200) and its higher order peaks were observed in the PbTe film. It is expected that it is feasible to obtain epitaxial PbTe film by RF magnetron sputtering.
Polycrystalline thin films of lead sulphide were deposited on glass substrates by the hot wall te... more Polycrystalline thin films of lead sulphide were deposited on glass substrates by the hot wall technique. The grain size varied from 100 to 500 A by varying the growth rate and the substrate temperature. The grain boundaries are assumed to influence the optoelectronic properties of polycrystalline films by generating potential energy relieves, estimated to reach 0.1 eV. We investigated the influence of the barrier height by introducing impurity atmospheres into the grain boundaries. Oxygen and indium were introduced into the films by diffusion from a gas phase. Conductivity was measured in the 80-300 K range. It rises with increasing temperature in oxygen doped films, indicating that conductivity is a thermal activation process. In the same time the conductivity of In doped PbS films decreases with temperature like in PbS single crystals. Photoconductivity was observed in films annealed in oxygen, which was significant up to room temperature. Carrier lifetime was found to decrease w...
ABSTRACT The present paper is concerned with the solution of the problem of a finite coherent pre... more ABSTRACT The present paper is concerned with the solution of the problem of a finite coherent precipitate in an elastic isotropic and homogeneous layer. The positive hydrostatic pressure in the matrix near a dilating precipitate is deduced by comparing the displacements in a layer to those in an infinite solid. The positive hydrostatic pressure gives rise to an attractive elastic interaction between like particles that increases monotonically with decreasing interparticle distance. The attractive interaction is maximal when the particles become of equal size and it increases as they grow closer to the free surfaces. The correlations that result from the elastic interaction in the thin layers generate a tendency toward clustering of equal-sized particles. The self-energy of an isolated precipitate decreases rapidly as it grows closer to the free surfaces favoring, at the advanced stages of the precipitation, precipitate coalescence rather than clustering.
Concepts and Challenges in the Biophysics of Hearing - Proceedings of the 10th International Workshop on the Mechanics of Hearing, 2009
255 THE ANISOTROPY OF THE TECTORIAL MEMBRANE GUIDES STEREOCILIA DEFLECTION R. GUETA1, D. BARLAM2,... more 255 THE ANISOTROPY OF THE TECTORIAL MEMBRANE GUIDES STEREOCILIA DEFLECTION R. GUETA1, D. BARLAM2, RZ SHNECK3, I. ROUSSO1 1 Dept. of Structural Biology, Weizmann Institute of Science, Israel 2 Mechanical Engineering, Ben-Gurion University oftheNegev, ...
ABSTRACT Two ways to calculate the elastic interaction between quantum dots (QDs) in the framewor... more ABSTRACT Two ways to calculate the elastic interaction between quantum dots (QDs) in the framework of linear elasticity are introduced and shown to vary in a similar way as the hydrostatic pressure. It is shown that the hydrostatic stress is the potential for the elastic interaction energy. The approach was used to estimate quantitatively the interaction energy between QDs in material systems that may form vertical order, anticorrelated order and FCC superlattice. The vertical interaction energy is very small compared with the thermal energy, nevertheless it is just enough to induce vertical ordering of QDs between layers. The attractive lateral interaction is an order of magnitude smaller than the vertical interaction, therefore ordering of multilatered QDs is made possible only by the vertical interactions. Several experimental observations are explained based on this understanding. The lateral interactions are small due to the small stresses set in the substrate after relief of the misfit strains in the free space. The vertical interactions are larger due to the large tensile stresses set up in the thin layer of matrix that separates an embedded QD from the free surface.
Proceedings of the National Academy of Sciences, 2006
The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the coc... more The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the cochlea. Its strategic location, together with the results of recent TM-specific mutation studies, suggests that it has an important role in the mechanism by which the cochlea transduces mechanical energy into neural excitation. A detailed characterization of TM mechanical properties is fundamental to understanding its role in cochlear mechanics. In this work, the mechanical properties of the TM are characterized in the radial and longitudinal directions using nano- and microindentation experiments conducted by using atomic force spectroscopy. We find that the stiffness in the main body region and in the spiral limbus attachment zone does not change significantly along the length of the cochlea. The main body of the TM is the softest region, whereas the spiral limbus attachment zone is stiffer, with the two areas having averaged Young's modulus values of 37 ± 3 and 135 ± 14 kPa, respect...
Modelling and Simulation in Materials Science and Engineering, 1995
... In the second problem, we calculate the stresses in a solid plate of thickness 2h, acting on ... more ... In the second problem, we calculate the stresses in a solid plate of thickness 2h, acting on its two surfaces z = h and z = -h, by tractions of the same magnitudes as calculated above but of opposite signs, T: = -U;; r: = -U; and q* = -uz (figure I@)). The superposition of the two ...
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Papers by Roni Shneck