Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Influence of composition on optical and dispersion parameters of thermally evaporated non-crystalline Cd50S50−xSex thin films

Neural stimulation with high spatial and temporal precision is desirable both for studying the real-time dynamics of neural networks and for prospective clinical treatment of neurological diseases. Optical stimulation of genetically targeted neurons expressing the light sensitive channel protein Channelrhodopsin (ChR2) has recently been reported as a means for millisecond temporal control of neuronal spiking activities with cell-type selectivity. This offers the prospect of enabling local delivery of optical stimulation and the simultaneous monitoring of the neural activity by electrophysiological means, both in the vicinity of and distant to the stimulation site. We report here a novel dual-modality hybrid device, which consists of a tapered coaxial optical waveguide (‘optrode’) integrated into a 100 element intra-cortical multi-electrode recording array. We first demonstrate the dual optical delivery and electrical recording capability of the single optrode in in vitro preparations of mouse retina, photo-stimulating the native retinal photoreceptors while recording light-responsive activities from ganglion cells. The dual-modality array device was then used in ChR2 transfected mouse brain slices. Specifically, epileptiform events were reliably optically triggered by the optrode and their spatiotemporal patterns were simultaneously recorded by the multi-electrode array.

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Integrated device for optical stimulation and spatiotemporal electrical recording of neural activity in light-sensitized brain tissue

Enhanced the photocatalytic activity of Ni-doped ZnO thin films: Morphological, optical and XPS analysis

Synthesis and characterization of zinc oxide thin films for optoelectronic applications

Physical properties of gallium and aluminium co-doped zinc oxide thin films deposited at different radio frequency magnetron sputtering power

Low temperature synthesis of radio frequency magnetron sputtered gallium and aluminium co-doped zinc oxide thin films for transparent electrode fabrication

This paper presents the structural, optical and photoluminescence properties of wet chemically synthesized ZnO:Pd2+ colloidal nanocrystals characterised by X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopic techniques. Increase in lattice parameters from diffraction data indicates the incorporation of Pd2+ in the ZnO crystal lattice. A small amount of dopant favours the formation of stoichiometric ZnO nanoparticles; otherwise, non-stoichiometric nanocrystal formation was observed from the EDS data. The optical gap was found to decrease with the doping concentration, except for the small dopant level of 0.05% of Pd2+ where an increase in the optical gap was observed. Intensities of characteristic luminescence bands for pure ZnO nanocrystals (357, 387 and 420 nm) were found to decrease with the increasing Pd2+ concentration, and two new bands centred at 528 and 581 nm for 0.5% Pd2+ concentration were observed. These results have been explained on the basis of change in the oxygen vacancy-related defects and/or formation of new trap states which in turn affect the luminescence properties of ZnO:Pd2+ nanocrystals, which are important in the realisation of visible light-emitting solid-state devices.

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Structural, optical and fluorescence properties of wet chemically synthesized ZnO:Pd2+ nanocrystals

Effect of O2/Ar flow ratio on Ga and Al co-doped ZnO thin films by rf sputtering for optoelectronic device fabrication

Bulk sample of (Se 80 Te 20 ) 96 Ag 4 was prepared by quenching technique. Thin films of (Se 80 Te 20 ) 96 Ag 4 glasses of different thickness (500–950 nm) were deposited on dry clean glass substrates by thermal evaporation technique. Energy dispersive X-ray spectroscopy (EDX) indicates that samples are nearly stoichiometric. X-ray diffraction patterns indicate that they are in the amorphous state. The optical constants, refractive index, absorption index, and optical band gap have been calculated from transmittance and reflectance data in spectral range of 400–2500 nm. It has been found that the optical band gap decreases, but the refractive index, extinction coefficient, optical conductivity, real and imaginary dielectric constant increase with increase in thickness of (Se 80 Te 20 ) 96 Ag 4 thin films. The results are discussed on the basis of rearrangements of defects and disorders in the chalcogenide systems.

T.S. Sathiaraj

Papers

Physical properties of gallium and aluminium co-doped zinc oxide thin films deposited at different radio frequency magnetron sputtering power

Low temperature synthesis of radio frequency magnetron sputtered gallium and aluminium co-doped zinc oxide thin films for transparent electrode fabrication

Structural, optical and fluorescence properties of wet chemically synthesized ZnO:Pd2+ nanocrystals

Effect of O2/Ar flow ratio on Ga and Al co-doped ZnO thin films by rf sputtering for optoelectronic device fabrication

Influence of thickness on optical properties of a-(Se80Te20)96Ag4 thin films