The optical constants (n,K) of vacuum-evaporated polycrystalline CdSe thin films are determined over 900–3100 nm photon wavelengths. Variation of band gap and optical constants with film thickness and substrate temperature is studied. Anomalous variation of refractive index near the band gap is explained by the volume and surface imperfections. Average spin-orbit splitting of valence band (0.32) is estimated for the films deposited on mica substrates. A theoretical plot of refractive index near the band edge is done. The dispersion of refractive index in films is studied by considering a single-oscillator model.

The coarse-grained alluvial succession of the Proterozoic Mancheral Quartzite encloses within it a few 2-6 m-thick, typically salmon red, fine-grained, very well-sorted sandstone units. Some 25-40% of the fine-grained sandstone units is aeolian --mostly adhesion laminae with subordinate adhesion cross-laminae and wind-ripple strata. The remainder of the sequence is aqueous; either massive or with faintly-developed trough cross-bedding. Based on their grain size, sorting and roundness, the bulk of the aqueous deposits appear to be reworked aeolian deposits. Thick adhesion laminated units within them show a number of superimposed drying-upwards sequences, represented by an upward decrease in laminae spacing within each of the sequences. Individual dryingupwards sequences, 5-15 cm thick, are in places bounded by disconformity surfaces marked by iron crusts.Stratigraphic relationships with associated fluvial facies indicate that these aeolian sandstones formed in the distal part of the floodplain. An arid climate, vegetation-free landscape, quickly avulsing channel behaviour and rapid basin subsidence favoured development and preservation of these rather thick alluvial plain aeolian deposits. Fluvial dynamics, in contrast to the erg dynamics as interpreted from other interlayered aeolianfluvial deposits, was the primary control on the depositional features and their internal organization within these aeolian sandstone units.

The optical constants (the refractive index n and the absorption constant K) and absorption coefficients x are measured on CdTe thin films in the wavelength range 500 to 2000 nm. Some parameters which affect these optical properties of thin films, such as the film thickness, substrate temperature, doping with impurities like In, BaF2, PbCI2 are also investigated. Effective crystallite size and strain are determined by the method of variance analysis of the X‐ray diffraction line profiles on the same films. It is observed that there is an increase in optical band gap with decrease in crystallite size and increase in strain.

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