Materials Literature
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Abstract We report comparisons of electron inelastic mean free paths (IMFPs) determined from our predictive IMFP equation TPP‐2M and reference IMFPs calculated from optical data. These comparisons were made for values of the parameter N v (the number of valence electrons per atom or molecule) that we have recommended…
Fluorescence and two-photon excitation (TPE) spectra are reported for a single crystal of the elpasolite, Cs2NaTbBr6, at low temperatures. Energy levels of the f8 Tb(III) manifold are located and assigned in the range up to 39 400 cm−1 A cubic to tetragonal phase transition occurs below ∼155K. Small spectral splitting…
Electron–phonon coupling and the normal and possible superconducting states in the monoanions of B, N-substituted acenes such as B3N3H6, B5N5H8, and B7N7H10 are studied. The results for B, N-substituted acenes are compared with those for acenes. The B–N stretching modes around 1500 cm−1 and the low-frequency modes, le…
The structural evolutions of glassy carbon (GC) and graphitized glassy carbon (GGC) treated under high temperatures and high pressures have been studied by energy-dispersive x-ray diffraction in a diamond anvil cell. The equations of state of GC and GGC are determined from x-ray density data. GC has a higher bulk modu…
The luminescence from conjugated polyelectrolytes that contain pendant metal complex units is quenched very efficiently by oppositely charged electron acceptors.
The intergrain magnetoresistance (IMR) of polycrystalline Sr2FeMoO6 is known to depend on its grain size and the tunnel barrier thickness formed during fabrication. Further enhancement of the IMR of Sr2FeMoO6 is found possible by further decreasing its grain size using high-energy ball milling, as well as by judicious…
We show experimentally that a layer of silicon nanocrystals, prepared by the Si-ion implantation (with the energy of 400 keV) into a synthetic silica slab and exhibiting room-temperature red photoluminescence, can serve simultaneously as a single-mode planar optical waveguide. The waveguide is shown to self-select gui…
I consider a brush of gradient polymers, with the chains anchored at their pure A ends with the chemical composition changing linearly along the chain up to the untethered chain tips whose composition is pure B. Demixing of the A and B monomers results in the creation of a thermally-controllable zone from which free e…
The relaxation dynamics of a rubbed polystyrene (PS) surface have been characterized using infrared-visible sum frequency generation spectroscopy (SFG). The SFG results were compared with previous relaxation of retardation measurements, and the results show that the rubbed PS surface has the same T(g) as the bulk wher…
Primary nucleation of poly(vinylidene fluoride) (pVDF) from bulk entangled amorphous polymer melts has been observed from molecular dynamics (MD) simulations. This is the first instance of spontaneous primary nucleation of an entangled bulk polymer in a MD simulation. The melt-to-crystal phase transition occurs via a…
Poly(L-lactic acid) samples of varying regio regularity were studied by static and dynamic laser light scattering in conjunction with Raman spectroscopy. Light scattering results allow an estimate of the characteristic ratio, C∞. Experimental values were compared to the characteristic ratio computed from structural pa…
We report Monte Carlo simulations of the melting of a single-polymer crystallite. We find that, unlike most atomic and molecular crystals, such crystallites can be heated appreciably above their melting temperature before they transform to the disordered “coil” state. The surface of the superheated crystallite is foun…
Blazed gratings have been fabricated using gray-scale X-ray lithography. The gratings have high efficiency, low parasitic light, and high groove quality. The fabrication technique and resist characterization are described. The gratings can be generated over a considerable range of distances from the X-ray mask, thus d…
Highly-ordered GaAs/AlGaAs quantum-dot arrays (QDA) were grown by molecular-beam epitaxy on GaAs (001) using masks of anodic nanochannel alumina (NCA). The QDA replicated the hexagonal lattice pattern of the NCA masks with period spacing of 100 nm. The circular disk-like dots were defined by the nanohole channels of N…
One of the long-standing problems to improve the resolution of organic electroluminescence devices has been related to the fabrication of very smooth, high-quality indium tin oxide (ITO) layers at room temperature. It seems that this problem could be solved by low-energy oxygen-ion-beam assisted electron-beam evaporat…
The structural (α-) relaxation in diglycidylether of bisphenol A (DGEBA) has been examined using three spectroscopic methods: dielectric spectroscopy (DS), dynamic light scattering–photon correlation spectroscopy (LS), and mechanical spectroscopy. The DS and LS measurements were carried out as a function of both tempe…
Through the analysis of the magnetic properties and of the nuclear magnetic resonance response of La2/3Ca1/3MnO3 ceramics with different grain sizes, we have found that poorly conducting regions, some ferromagnetic and some weakly magnetic, are located at the surface of the grains. We state that these regions constitu…
Diamond is a material which displays exceptional electronic, thermal, tribological, elastic and acoustic properties. These exceptional properties make diamond extremely difficult to characterize. In particular, diamond displays the highest acoustic velocities of any material making it an ideal candidate for acoustic w…
The highly conductive surface layer induced in diamond by hydrogen termination has been used to fabricate in-plane gate transistors. The conductive channel has been separated from the Ohmic gate contacts by insulating thin lines, obtained by using a combination of electron-beam lithography with surface oxidation. Oxid…
YAl 3 (BO 3 ) 4 crystals doped with Dy 3+ were grown from a potassium trimolybdate flux. Their absorption and visible emission spectra and decay curves were measured at temperatures ranging from 10 to 298 K. The complete energy level scheme has been deduced from the low temperature measurements and reproduced by theor…