Molecular Organization of Polylactides Immobilized on a Flat Surface: Observation of Single Crystal Arrays of Homochiral and Stereocomplexed Polylactides

2012 ◽  
Vol 45 (15) ◽  
pp. 5993-6001 ◽  
Author(s):  
Hajime Nakajima ◽  
Maho Nakajima ◽  
Tomoko Fujiwara ◽  
Chan Woo Lee ◽  
Takashi Aoki ◽  
...  
Keyword(s):  
Single Crystal ◽  
Flat Surface ◽  
Molecular Organization ◽  
Surface Observation

Fabrication and Magneto-Transport Properties of Zn0.88-xMgxMn0.12O/ZnO Heterostructures Grown on ZnO Single-Crystal Substrates

2010 ◽  
Vol 75 ◽  
pp. 1-8
Author(s):  
Keiichiro Masuko ◽  
Tatsuru Nakamura ◽  
Atsushi Ashida ◽  
Takeshi Yoshimura ◽  
Norifumi Fujimura
Keyword(s):  
Single Crystal ◽  
Transport Properties ◽  
Flat Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Force ◽  
Brillouin Function ◽  
Atomic Force Microscope Observation ◽  
Zno Single Crystal ◽  
Atomically Flat

The transport properties of Zn0.88-xMgxMn0.12O/ZnO modulation-doped heterostructures (x≤0.15) were investigated. The heterostructures were fabricated on ZnO single-crystal substrates by a pulsed laser deposition system. Atomic force microscope observation and X-ray diffraction analysis suggested that Zn0.88-xMgxMn0.12O layers have atomically flat surface and excellent crystallinity. The results of Hall measurement for Zn0.88-xMgxMn0.12O/ZnO modulation-doped heterostructure with x=0.075 revealed that the carrier concentration and the electron mobility were 5.1×1012cm-2 and 800 cm2/Vs at 10 K, respectively, suggesting that the carrier confinement effect exits at the heterointerface between Zn0.88-xMgxMn0.12O barrier layer and ZnO channel layer. In the magnetoresistance (MR) measurement at 1.85 K, a positive MR behavior was observed below 0.5 T, while a negative MR behavior was recognized above 0.5 T. The slope of the positive MR decreased with increasing the temperature and was well fitted to the Brillouin function with S=5/2. The electrical and magneto-transport properties were very similar to those of Zn0.88Mn0.12O/ZnO heterostructures without doping Mg.

Impact of Molecular Organization on Exciton Diffusion in Photosensitive Single-Crystal Halogenated Perylenediimides Charge Transfer Interfaces

2015 ◽  
Vol 7 (50) ◽  
pp. 27720-27729 ◽  
Author(s):  
Rui M. Pinto ◽  
Wilson Gouveia ◽  
Ermelinda M. S. Maçôas ◽  
Isabel C. Santos ◽  
Sebastian Raja ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Single Crystal ◽  
Molecular Organization ◽  
Exciton Diffusion

Some Fundamental Aspects of the Thin Film Organization and Device – Structure Fabrication of Polydiacetylenes

1987 ◽  
Vol 109 ◽  
Author(s):  
M. Thakur ◽  
B. Verbeek ◽  
G. C. Chi ◽  
K. J. O'BRIEN
Keyword(s):  
Single Crystal ◽  
Logic Gates ◽  
Optical Quality ◽  
Molecular Organization ◽  
Silicon Substrates ◽  
Device Structure ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Device Applications ◽  
First Time

ABSTRACTThe utility of the Shear method in obtaining thin single crystal films of polydiacetylenes has been demonstrated previously. In this paper the principles of the Shear method are elucidated with analogy to the well-known L-B method. Both the methods, L-B and Shear, utilize the polar molecular interactions with the substrates as a control parameter for the molecular organization. The major difference between the two is that one (L-B) utilizes a liquid as the subphase while the other (Shear) uses solid substrates. Because of the nature of the interface the L-B approach leads to only one-dimensional organization and poor optical quality for the films while the Shear method provides 3-D organization and excellent optical quality.Thin single crystal films of a specific polydiacetylene, PTS, are prepared on oxide coated silicon substrates by the Shear method. Waveguiding through the PTS films is demonstrated for the first time. Much progress is also made in the waveguide-structural fabrication of PTS films. The results are quite encouraging in terms of device applications of polydiacetylenes as optical switches and logic gates.

Wet and Dry Oxidation of Single Crystal β-SiC: Kinetics and Interface Characteristics

1985 ◽  
Vol 54 ◽  
Author(s):  
John W. Palmour ◽  
H. J. Kim ◽  
R. F. Davis
Keyword(s):  
Activation Energy ◽  
Silicon Dioxide ◽  
Single Crystal ◽  
Flat Surface ◽  
Parabolic Rate Constant ◽  
Wet Oxidation ◽  
Interface Characteristics ◽  
Dry Oxidation ◽  
Parabolic Relationship ◽  
Parabolic Rate

ABSTRACTSilicon dioxide layers were grown on single crystal (100) β-SiC between 1000°C and 1200°C, in wet O2, dry O2, and wet Ar. All processes demonstrated a linear-parabolic relationship with time. Both wet processes had a slower rate than dry oxidation at 1050°C and below. The activation energies of the linear and parabolic rate constants were calculated for each process. The activation energy of the parabolic rate constant for wet oxidation was found to be inversely dependent on the amount of oxygen present as a carrier gas.The dry oxides exhibited a very flat surface; in contrast, SEM and XTEM reveal that wet oxidation preferentially oxidizes dislocation bands, causing raised lines on the oxide and corresponding grooves in the SiC. It is proposed that the much higher solubility of H2O in SiO2 as compared with that of O2 (103 at 1000°C), allows wet oxidation to be preferential.

New Crucible Design for SiC Single Crystal Growth by Sublimation

2000 ◽  
Vol 640 ◽  
Author(s):  
Shin-ichi Nishizawa ◽  
Hirotaka Yamaguchi ◽  
Tomohisa Kato ◽  
M. Nasir Khan ◽  
Kazuo Arai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Growth Rate ◽  
Crystal Growth ◽  
Single Crystal ◽  
Flat Surface ◽  
Single Crystal Growth ◽  
Crystal Growth Rate ◽  
Bulk Single Crystal ◽  
High Quality ◽  
Better Than

ABSTRACTSiC bulk single crystal growth by sublimation was investigated. A new crucible design, double-walled crucible, was proposed, and its effect was confirmed numerically and experimentally. On the point of heat transfer in a growth cavity, double-walled crucible is better than conventional crucible. With a double-walled crucible, temperature of seed and source surfaces could be kept constant with better uniformity than that with a conventional crucible. It was deduced that a crystal growth rate could be kept constant with flat surface. Furthermore, in case of a double walled crucible, crystal enlarged rapidly with less inclusion. As the results, a double-walled crucible is useful to grow high quality SiC single crystal by sublimation.

A Preparation of High Resolution Standards for Electron Microscopy. Part II

1971 ◽  
Vol 29 ◽  
pp. 160-161
Author(s):  
Akira Tanaka ◽  
David F. Harling
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Carbon Black ◽  
Single Crystal ◽  
Dark Field ◽  
Graphitized Carbon Black ◽  
Graphitized Carbon ◽  
Dark Field Imaging ◽  
Crystal Films ◽  
Micro Holes

In the previous paper, the author reported on a technique for preparing vapor-deposited single crystal films as high resolution standards for electron microscopy. The present paper is intended to describe the preparation of several high resolution standards for dark field microscopy and also to mention some results obtained from these studies. Three preparations were used initially: 1.) Graphitized carbon black, 2.) Epitaxially grown particles of different metals prepared by vapor deposition, and 3.) Particles grown epitaxially on the edge of micro-holes formed in a gold single crystal film.The authors successfully obtained dark field micrographs demonstrating the 3.4Å lattice spacing of graphitized carbon black and the Au single crystal (111) lattice of 2.35Å. The latter spacing is especially suitable for dark field imaging because of its preparation, as in 3.), above. After the deposited film of Au (001) orientation is prepared at 400°C the substrate temperature is raised, resulting in the formation of many square micro-holes caused by partial evaporation of the Au film.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Dislocations, Ordering and Antiferromagnetic Domains in MnO

1970 ◽  
Vol 28 ◽  
pp. 522-523
Author(s):  
D. J. Barber ◽  
R. G. Evans
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Optical Microscopy ◽  
Defect Chemistry ◽  
Magnetic Structures ◽  
Optically Transparent ◽  
Magnetic Features ◽  
Antiferromagnetic Domains

Manganese (II) oxide, MnO, in common with CoO, NiO and FeO, possesses the NaCl structure and shows antiferromagnetism below its Neel point, Tn∼ 122 K. However, the defect chemistry of the four oxides is different and the magnetic structures are not identical. The non-stoichiometry in MnO2 small (∼2%) and below the Tn the spins lie in (111) planes. Previous work reported observations of magnetic features in CoO and NiO. The aim of our work was to find explanations for certain resonance results on antiferromagnetic MnO.Foils of single crystal MnO were prepared from shaped discs by dissolution in a mixture of HCl and HNO3. Optical microscopy revealed that the etch-pitted foils contained cruciform-shaped precipitates, often thick and proud of the surface but red-colored when optically transparent (MnO is green). Electron diffraction and probe microanalysis indicated that the precipitates were Mn2O3, in contrast with recent findings of Co3O4 in CoO.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

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