Electronic Structure of Crystalline and AmorphousAs2S3and

Transport properties and electronic structure of glasses in the arsenic-selenium system

“…It may be, of course, that the different properties show extrema (or minima) a t different compositions due to factors such as microscopic compositional variations. Recent X-ray and neutron scattering experiments (Apling 1974) have shown that As,Se, is a comparatively well-ordered glass, in which structural correlations reminiscent of the crystal extend out to a t least 10 d. This conclusion is corroborated by the spectrographic work of Zallen, Drews, Emerald and Slade, (1971) and Lucovsky (1972). These results and the data obtained in the present studies indicate that the appreciable remanent short -and intermediate-range order lead to a band structure in which moderately well defined sets of localized levels-probably closely associated with defect states in the corresponding crystalline modifications-are retained, and that it is these states which control the measured trap-limited drift mobility.…”

Electronic and phononic properties of cinnabar:Ab initiocalculations and some experimental results

“…8 The experimental values are throughout the whole spectral range lower than the calculated ones, a fact which cannot be completely attributed to experimental errors: measurements at energies below the gap (E ≈ 0) give ǫ 1 = 8.4 for E c and ǫ 1 = 6.9 for E ⊥ c (note that ǫ 1 = 8.4 is the highest value of ǫ 1 (0) found for any mineral). However, although the calculations give values of ǫ larger than the experimental ones, the calculated birefringence (ǫ 1 -ǫ 1⊥ ) and its sign agrees roughly with the measured one.…”

Evidence from photoluminescence studies for a low-energy absorption tail in chalcogenide glasses and crystals

“…When ad < 1, I , = const adRy, and any spectral variation in R and y , may be significant when calculating a. However, the reflectivity data of Zallen, Drews, Emerald and Slade (1971) show that R is constant to within "5% over the spectral region discussed here, whereas a changes by more than an order of magnitude. The evidence on the spectral variation in y L is discussed below.…”

“…Using this method, ad values in the chalcogenides have been measured down to compared with a lower limit of -in transmission spectroscopy. This extra sensitivity is especially valuable when the range of sample thickness is limited, as with present chalcogenide crystals where the published a values do not extend below 10cm-l (Zallen et al 1971).…”