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A simple scanning transmission electron microscope has been built using a field-emission electron source, a new electron gun, and one lens to produce a high-contrast picture with 30 Å resolution. The final spot size is limited by the properties of the lens, in the same manner as a conventional transmission microscope.…
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCalibration of the methanol and glycol nuclear magnetic resonance thermometers with a static thermistor probeAnthony L. Van GeetCite this: Anal. Chem. 1968, 40, 14, 2227–2229Publication Date (Print):December 1, 1968Publication History Published online1 May 2002Published inis…
Abstract Es wird gezeigt, wie aus Messungen der Winkelabhängigkeit der Linienbreite in Röntgenweitwinkeldiagrammen von Hochpolymeren die kristallitgröße und die Gitterstörungen bestimmt werden können. In lösungskristallisierten linearen Polyäthylenen treten rein parakristalline Gitterstörungen auf, die thermodynamisch…
Abstract The transport behavior of a number of permanent gases of varying molecular size and of water vapor was studied in calendered films of unplasticized poly(vinylchloride). Permeabilities, diffusivities, and solubilities were measured over a range of temperatures traversing the glass transition. A discrete change…
Abstract The morphology and growth of extended chain crystals of polyethylene is discussed on the basis of optical and electron microscopy. The spherulitic habit is shown to be caused by nucleation of new lamellae on the (001) surface of lamellae, branching of lamellae on their growth face, and thickening of lamellae.…
Abstract In order to elucidate the relationship between IR‐spectra and the sequence lengths of the segments which assume the regular helical conformation in isotactic polymer chains, the IR‐spectra have been measured for isotactic copolymers of normal and deuterated styrenes in various ratios. The absorption intensiti…
A crystal deformation twin may be visualized to form and grow the movement of partial dislocations only if the twinning dislocations especially distributed to give an invariant shear. One consequence of this requirement is that, if a critical resolved twinning stress exists in the same sense twinning as for slip, this…
Characteristic loss spectra have been obtained in a reflection scattering geometry for liquid Al, Bi, In, Ga, Hg, and Au and, in the case of Al, Bi, and Au, for the same specimens in the solid phase. Peaks due to surface and volume plasmon excitation dominated the loss spectra for all elements except Au. The relative…
The vibrations of PO4−3 ions in single crystals of hexagonal Ca10(PO4)6F2 have been observed by means of polarized Raman scattering and polarized infrared reflectance. The T2(ν3) and T2(ν4) Raman vibration frequencies are each observed to split in accord with the predictions of the factor group of the unit cell. The o…
The crystal structures of the spinels Co 3 O 4 , NiCo 2 O 4 , Co 3 S 4 , and NiCo 2 S 4 were refined from X-ray and neutron powder data. Their lattice parameters at room temperature and the positional parameters of the oxygen and sulfur atoms were: Co 3 O 4 , 8.0835 ± 6 Å, 0.2640 ± 8; NiCo 2 O 4 , 8.114 ± 14 Å, 0.2583…
The free-ion energy level scheme of Gd3+ (aquo) to ∼52 000 cm−1 has been determined from the absorption spectrum of Gd3+ in dilute acid solution at 25°C. Several new absorption bands near 50 000 cm−1 have been ascribed to transitions from the ground state to components of the 6G multiplet. Energy level assignments wer…
Fifteen of the sixteen known enstatite chondrites were studied microscopically in reflected and transmitted light, and their modal compositions were determined by point-counting techniques. Compositions of clinoenstatite, orthoenstatite, plagioclase, kamacite, taenite, troilite, oldhamite, daubreelite, niningerite, fe…