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Selectively deuterated glycerol has been subjected to 2 H-NMR spin-lattice relaxation and quasi-elastic neutron scattering experiments. The measurements yield relaxation rates and a non-Gaussian Q -dependence of the Debye-Waller factor which are different for the two hydrogen sites. The data analysis shows that below…
Dense fluids of biaxial hard convex bodies exhibit a phase transition from an isotropic to a nematic (I–N) liquid–crystalline state. In the Onsager theory, the I–N transition is attributed to the tendency of pairs of molecules to minimize their excluded volume (or second virial coefficient, B2 ). In the present work,…
Measurements of the dynamics of NH(X3∑−, v =1–3), created in electron-irradiated N2/H2 and Ar/N2/H2 mixtures, have been performed. Time-resolved Fourier spectroscopy was used to observe NH(v→v–1) vibrational fundamental band emission. Time-dependent populations were then determined by spectral fitting. Subsequent kine…
Abstract The complex polymorphic behavior of syndiotactic polystyrene (s‐PS) in melt‐crystallized samples is altered by blending with poly (2,6‐dimethyl‐1,4‐diphenylene oxide) (PPO). In particular, to render the beta form in these blends, starting with samples containing the α or γ froms, requires much lower temperatu…
Abstract The synthesis and living cationic polymerization of 11‐[(4‐cyano‐4′‐biphenyl)oxy]‐undecanyl vinyl ether ( 6 – 11 ) are described. The mesomorphic phase behavior of poly( 6 – 11 ) with different degrees of polymerization was compared to that of 6 – 11 and of 11‐[(4‐cyano‐4′‐biphenyl) oxy] undecanyl ethyl ether…
We present calculations of the local frequency spectrum of 〈110〉-split-interstitial atoms in bcc metals with the use of the Green's-function method. The dumbbell vibrates with low-frequency resonant modes and high-frequency localized modes with little contribution from the host frequencies. In agreement with experimen…
A useful magnitude of angular selective transmittance of incident unpolarized light is demonstrated in obliquely deposited aluminum. Required deposition procedures and anisotropic optical properties are discussed. Angular selectivity is very strong at visible wavelengths but both experiment and theory indicate that a…
Abstract A series of novel dialdehydes as new monomers, 4,4′‐diformyl‐α,ω‐diphencarbonylalkane, 4,4′‐diformyl‐3,3′‐methoxy‐α,ω‐diphencarbonylalkane, and 4,4′‐diformyl‐3,3′‐ethoxy‐α,ω‐diphencarbonylalkane, was prepared from aliphatic diacid chloride with p ‐hydroxybenzaldehyde, vanillin, and 3‐ethoxy‐4‐hydroxybenzaldeh…
The kinetics of decomposition of formic acid on Ru(001) have been investigated with thermal desorption mass spectrometry following the adsorption of DCOOH and HCOOH at both 130 and 305 K. Formic acid chemisorbs dissociatively on the perfect (001) surface via O–H bond cleavage to form a formate and a hydrogen adatom, a…
Abstract The overall crystallization and crystal melting of one low‐molecular mass poly(ethylene oxide) (PEO) fraction (MW 3000) have been investigated by differential scanning calorimetry (DSC) and in situ small‐angle x‐ray scattering (SAXS). The salient new results indicate that initial transient crystals with nonin…
It is known that polyalkylthiophenes show reversible thermochromism within a well-defined temperature range. The vibrational infrared and Raman spectra are used as structural probes for understanding the structures of polyhexyl and polyoctyl thiophenes at room temperature and their evolution with temperature during th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNear-Infrared Fluorogenic Labels: New Approach to an Old ProblemGabor Patonay and Miquel D. AntoineCite this: Anal. Chem. 1991, 63, 6, 321A–327APublication Date (Print):March 15, 1991Publication History Published online30 May 2012Published inissue 15 March 1991https://pubs.a…
Abstract An investigation of the influence of crystalline microstructure on fatigue crack propagation (FCP) in high‐density polyethylene (HDPE) is reported. Various thermal histories were used to generate samples with the same crystallinity and supermolecular structure for three different molecular weight HDPEs. Estim…
The charge carriers and band structure that evolve upon doping of electrochemically grown poly (3-methylthiophene) (PMeT) films are characterized as a function of film preparation conditions by optical absorption, infrared, and electron spin resonance measurements. Regardless of the solvent (acetonitrile or propylene…
The electronic structure of tetragonal zirconia with ${\mathit{D}}_{4\mathit{h}}^{15}$ symmetry is investigated using density-functional theory. The Kohn-Sham equations are solved by applying the full-potential linearized augmented-plane-wave method. The total energy as a function of the lattice parameters shows that…
We have studied the structural properties of a recently proposed, hypothetical, all-${\mathit{sp}}^{2}$ phase of carbon, using the first-principles pseudopotential total-energy method. Our results are compared with those of an earlier tight-binding calculation. While the two calculations yield equilibrium volumes and…
Abstract Correlations of the linear crystal growth rates with the change in crystal morphology for poly (ethylene oxide) (PEO) (MW 3000) and α,ω‐‐methoxy‐poly (ethylene oxide) (MPEO) (MW 3000) fractions have been established over a wide range of supercooling (Δ T = 25 K). Two linear crystal growth rates were measured,…
Undoped and rare-earth- (Pr, Nd, Eu, and Er) doped transparent Y3Al5O12 ceramics have been prepared, and their optical spectra have been measured. It is found that absorption coefficient of the undoped ceramic Y3Al5O12 is almost independent of wavelength with 0.258 cm−1, which gives transmittance of the undoped cerami…
Abstract New linear and three‐arm star thermoplastic elastomers (TPEs) comprising a rubbery polysobutylene (PIB) midblock flanked by glass polystyrene (PSt) blocks have been synthesized by living carbocationic polymerization in the presence of select additives by sequential monomer addition. First, isobutylene (IB) wa…
The vibrational spectra of a few oligomers of thiophene in the solid and solution are studied with the help of quantum mechanical calculations and of the theory of the effective conjugation coordinate recently developed. The aim of the work is to extract from the spectra structural probes to be used in the understandi…