Electrodeposition of lead sulphide in acidic medium

Polycrystalline thin films of lead sulphide were electrodeposited on titanium, aluminium and stainless steel (SS) substrates at a constant potential of -0.7V vs. Ag\AgCl\(sat)KCl electrode using 1 mM solutions of Pb(NO,), and Na2S2O3 at pH2.7, 2.8 and 2.9. Except at pH 2.9 (which also gave tetragonal PbS2) all other pHs gave single phase PbS (fee). While deposition on Al gave a crystalline phase of PbS with very prominent (200) and (111) planes, that on SS substrate showed growth of the (200) plane only. Although the deposition of PbS on Ti was good, it showed (111) and (200) planes of low intensity compared to that on Al. Film thickness and grain size were found to be of the order of micrometres. The cyclic voltammetry of the film formation was studied in a potential range -1 to OV (Ag\AgCl) followed by XRD, SEM and AFM analyses. The mechanism of growth is discussed. (C) 1997 Elsevier Science S.A

The petFI gene encoding ferredoxin I is located close to the str operon on the cyanelle genome of Cyanophora paradoxa

AbstractThe petFI gene encoding ferredoxin I was localized in the large single copy region of cyanelle DNA by heterologous hybridization. Sequence analysis revealed an ORF of 99 amino acids (including the N-tenninal processed methionine) at a position 477 bp from the 3' end of tufA but on the opposite strand. The 25 ammo-terminal residues well corresponded to partial sequences obtained with purified cyanelle ferredoxin. The assignment of yet another gene that is not found on the genomes of chlorophyll β-type plastids to cyanelle DNA again corroborates the special position of cyanelles serving as a model for plastid evolution from endocytobiotic cyanobacteria

Investigation of photomоdified semiconductor/ electrolyte interfaces : The n-lnSe/CulSe

An overlayer of CulSe3-Se° of i to 2 µm was photogenerated at the surface of n-InSe electrodes in a solution of copper polyiodide. The morphology, chemical composition, and crystal structure of these films were characterized by SEM, EDAX, X-ray diffraction under grazing incidence, ESCA and SIMS. The spectral properties were characterized by spectral photoresponse and photoreflectance and they were correlated with photoelectrochemicl1 and EBIC studies in order to determine the mechanism of charge transport across such layers

A study into the impact of sapphire substrate orientation on the properties of nominally-undoped β-Ga<inf>2</inf>O<inf>3</inf> thin films grown by pulsed laser deposition

© 2017 SPIE. Nominally-undoped Ga2O3 layers were deposited on a-, c- and r-plane sapphire substrates using pulsed laser deposition. Conventional x-ray diffraction analysis for films grown on a- and c-plane sapphire showed the layers to be in the β-Ga2O3 phase with preferential orientation of the (-201) axis along the growth direction. Pole figures revealed the film grown on r-plane sapphire to also be in the β-Ga2O3 phase but with epitaxial offsets of 29.5°, 38.5° and 64° from the growth direction for the (-201) axis. Optical transmission spectroscopy indicated that the bandgap was ∼5.2eV, for all the layers and that the transparency was > 80% in the visible wavelength range. Four point collinear resistivity and Van der Pauw based Hall measurements revealed the β-Ga2O3 layer on r-plane sapphire to be 4 orders of magnitude more conducting than layers grown on a- and c-plane sapphire under similar conditions. The absolute values of conductivity, carrier mobility and carrier concentration for the β-Ga2O3 layer on r-sapphire (at 20Ω-1.cm-1, 6 cm2/Vs and 1.7 x 1019 cm-3, respectively) all exceeded values found in the literature for nominally-undoped β-Ga2O3 thin films by at least an order of magnitude. Gas discharge optical emission spectroscopy compositional depth profiling for common shallow donor impurities (Cl, F, Si and Sn) did not indicate any discernable increase in their concentrations compared to background levels in the sapphire substrate. It is proposed that the fundamentally anisotropic conductivity in β-Ga2O3 combined with the epitaxial offset of the (-201) axis observed for the layer grown on r-plane sapphire may explain the much larger carrier concentration, electrical conductivity and mobility compared with layers having the (-201) axis aligned along the growth direction