Materials Literature
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This work presents a step furthering a new perspective of proactive control of the spin-exciton dynamics in the quantum limit. Laser manipulation of spin-polarized optical excitations in a semiconductor nanodot is used to control the spin dynamics of two interacting excitons. Shaping of femtosecond laser pulses keeps…
We report on the ESR, magnetization and magnetic susceptibility measurements performed over a large temperature range, from 1.5 to 750 K, on high-quality stoichiometric LiNiO2. We find that this compound displays two distinct temperature regions where its magnetic behavior is anomalous. With the help of a statistical…
During the directional solidification of peritectic alloys, two stable solid phases (parent and peritectic) grow competitively into a metastable liquid phase of larger impurity content than either solid phase. When the parent or both solid phases are morphologically unstable, i.e., for a small temperature gradient/gro…
We examine in full generality the phase behavior of systems whose constituent particles interact by means of potentials that do not diverge at the origin, are free of attractive parts, and decay fast enough to zero as the interparticle separation r goes to infinity. By employing a mean field-density functional theory…
The preparation of substituted glycolides can greatly expand the pool of monomers available for the synthesis of polyglycolides, and provide a broader range of physical properties for degradable polymers. Ethyl-, hexyl-, isobutyl-, and benzylglycolide were prepared and converted to high molecular weight polymers by ri…
Unexpected high photoemission intensity is observed on copper surfaces at grazing incidence angles of p-polarized light $(\ensuremath{\Elzxh}\ensuremath{\omega}=21.2\mathrm{eV}).$ The dipole approximation in combination with Fresnel's equations and the optical constants of copper is not sufficient to explain the exper…
We here present a series of ab initio quantum-chemical calculations on clusters of atoms modeling several oxygen-deficiency-related defects in amorphous silica and illustrate how these defect centers will change their atomic configurations upon photoionization. We first give theoretical evidence that structural conver…
We report an observation of holographic gratings recorded exposing a homogeneous mixture of pre-polymer and liquid crystal to a polarization light pattern. This polarization pattern is obtained by a superposition of two waves with orthogonal linear polarization. The idea to use this technique to realize holographic gr…
Chromium-doped aluminum nitride (AlN:Cr) films were grown on p-doped silicon (111) by rf magnetron sputtering in a nitrogen atmosphere at a pressure of 10−4 Torr. Film thickness was typically 200 nm. After growth, the films were “activated” at ∼1300 K for 30 min in a nitrogen atmosphere. Films activated in this manner…
Hydrogen passivation of Si nanocrystals is shown to result in a redshift of photoluminescence (PL) emission spectra, as well as the more commonly observed intensity increase. The shift is reversible, with spectra returning to their unpassivated values as hydrogen is removed from the samples by annealing. The magnitude…
We report on waveguiding properties in epitaxial Er:Y2O3 films grown by pulsed-laser deposition on sapphire [0001] substrate. Characterization of the as-grown films by x-ray diffraction, atomic force microscopy, and Rutherford backscattering revealed that the films were highly crystalline and textured along the [111]…
1.6 μm emission originated from Pr3+: (3F3,3F4)→3H4 transition in Pr3+- and Pr3+/Er3+-doped selenide glasses were investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and full width at half maximum of the fluorescent emission were ∼1650 and >100 nm, respectively…
Improved dielectric properties of lead zirconate titanate (PZT) films deposited on a variety of foils using buffer layers are reported. Foils include titanium, stainless steel, and nickel with LaNiO3(LNO) buffer layers which were prepared by sol–gel processing. High dielectric constant (330 for stainless steel, 420 fo…
The magnetic ground state of ${\mathrm{CuB}}_{2}{\mathrm{O}}_{4}$ is incommensurate at $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{K}$ and undergoes a continuous phase transition to a noncollinear commensurate antiferromagnetic state at ${T}^{\ensuremath{\star}}\ensuremath{\sim}10\mathrm{K}$. Close…
Atomic and electronic structures of the SrTiO3(100)-(square root of 5 x square root of 5) - R26.6 degrees surface are studied by using scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM). Instead of the well established oxygen vacancy model, it is found that a structural model, consisti…
A flat panel display prototype has been fabricated using gated carbon nanotubes as electron emission source. The gate structure is made by a self-aligned method. The pixels are turned “on” and “off” by controlling the gate electrode with a 50 V source. The operating properties of the display show much promise for furt…
The optical absorption spectra of Si(n)H(m) nanoclusters up to approximately 250 atoms are computed using a linear response theory within the time-dependent local density approximation (TDLDA). The TDLDA formalism allows the electronic screening and correlation effects, which determine exciton binding energies, to be…
We explore the electric-field effect of carbon nanotubes (NTs) in electrolytes. Due to the large gate capacitance, Fermi energy (EF) shifts of order ±1 V can be induced, enabling to tune NTs from p to n-type. Consequently, large resistance changes are measured. At zero gate voltage, the NTs are hole-doped in air with…
Recent low-temperature scanning tunneling experiments have challenged the generally accepted picture of buckled silicon dimers as the ground state reconstruction of the Si(100) surface. Together with the symmetric dimer model of the surface suggested by quantum chemistry calculations on small clusters, these findings…
A simple macroscopic continuum elasticity theory (CET) is used to calculate the structure relaxation of single-wall carbon nanotube (SWNT), an analytic formula is obtained. We also expand an atomic scale three-parameter empirical model [ T. Lenosky {\emph et al.} Nature 355, 333(1992)] in order to correctly describe t…