Polycrystalline Cr2O3 films are prepared by normal pressure chemical vapour deposition (CVD), and electrical and optical properties of the films are investigated. The films are transparent from 800 to 1000 nm wavelength, and absorbing for wavelengths shorter than 800 nm. The optical band gap energy is Eopt = 2.98 to 3.09 eV for films formed at different substrate temperatures. The electrical conductivity σ of the films is from 1 × 10−2 to 2.5 × 10−3 S cm−1 at 500 K. The films are p‐type semiconducting. At temperatures higher than 500 K. the conduction is due to small polaron hopping. For temperatures lower than 500 K, a T−1/4 dependence of σT1/2 is found, which is attributed to variable‐range hopping.
The morphology of snow crystals growing at a low temperature has been experimentally studied. The habit and the morphological instability of the crystals vary remarkably with air pressure. In addition, the morphological instability of the crystals depends not only on air pressure but also on supersaturation, crystal size, the ratio of growth rates and the ratio of axial lengths. It is supposed from the experimental results that long prisms with small skeletal structures forming at low supersaturation are precipitating in polar regions.
We measured the spectrum of cesium emitted by a pulsed radio-frequency discharge in the region 1550 Å to 40 000 Å using concave grating spectrographs, Fabry-Perot interferometry, and Fourier transform spectroscopy. By varying the operating parameters of the discharge, we identified approximately 1700 of the more than 3000 spectral lines observed in this region as belonging to the spectrum of singly-ionized cesium (Cs II). Of these, 1683 were classified as transitions among 118 even and 165 odd energy levels. Partially or fully resolved hyperfine structure was analyzed for 579 lines.
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