Electronic Processes in Zinc Oxide

Optical resonances in polygonal resonators are due to whispering gallery modes (WGM). We investigate WGM in regular and deformed hexagonal ZnO microwire resonators. Four types of geometries are investigated: regular hexagonal and dodecagonal cross sections, hexagonal cross section elongated for one pair of facets and hexagonal cross section deformed by bending (uniaxial stress). Experimental data on mode energies and angular dispersion are correlated with model calculations and Poincaré surfaces of section. Hexagonal (ϕ = 60°), square (ϕ = 45°), triangular (ϕ = 30°), and Fabry–Pérot modes (ϕ = 0°) are observed in the various investigated geometries, ϕ being the angle of incidence at the facets with respect to the normal direction. magnified image Hexagonal WGMs (green, 6‐WGM), triangular (red, 3‐WGM), and double‐triangular (blue, D3‐WGM) rays in regular hexagons, elongated hexagons and hexagons deformed by bending. Triangular WGMs are stable modes in all three resonators. Hexagonal modes are not stable in the bent hexagon.

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“…3b), available with various radii. We note that prismatic ZnO crystals had found interest already a long time ago [39].…”

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confidence: 89%

Whispering gallery modes in deformed hexagonal resonators

Grundmann

Dietrich

2012

Physica Status Solidi (b)

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“…The effects of variables including m-cresol concentration, photocatalyst loading and pH on photodegradation were studied. In addition, the mineralisation and photoproducts were investigated by total organic carbon (TOC) measurement (Heiland, et al, 1959) and Waters-Acquity ultra high pressure liquid chromatography (UPLC).…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of m-cresol by Zinc Oxide under Visible-light Irradiation

Abdollahi¹,

Abdullah²,

Zainal³

et al. 2011

IJC

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The photodegradation of m-cresol was carried out under visible light (46% sunlight) by ZnO as photocatalyst. To measure the efficiency of photodegradation, the different variables studied included amount of photocatalyst, concentration of m-cresol and pH. The maximum amount of photocatalyst and concentration of m-cresol was 1.5 g/L and 25 ppm respectively. The photodegradation was favorable in the pH 6-9 range. The detected intermediates were 2-methyl-1,4-benzodiol, 2-methyl-para-benzoquinone, 3,5-dihydroxytoluene and 2,5-dihydroxy-benzaldehyde. TOC studies show that 78% of total organic carbon is removed from solution during irradiation time. This study indicates the great potential of ZnO to remove aqueous m-cresol under visible-light irradiation which is part of sunlight.

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“…ZnO is receiving a great deal of attention recently as a candidate material for short wavelength emitters, in particular due to its large exciton binding energy and the availability of lattice matched substrates which give it substantial advantages over GaNbased devices [1][2][3].…”

Section: I: Introductionmentioning

confidence: 99%

Effect of polycrystallinity on the optical properties of highly oriented ZnO grown by pulsed laser deposition

McGlynn

2004

Thin Solid Films

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We report the results of photoluminescence and reflectance measurements on highly caxis oriented polycrystalline ZnO grown by pulsed laser deposition. The samples measured were grown under identical conditions and were annealed in-situ at various temperatures for 10-15 minutes. The band-edge photoluminescence spectra of the material altered considerably with an increase in grain size, with increased free exciton emission and observable excitonic structure in the reflectance spectra. The green band emission also increased with increasing grain size. A deformation potential analysis of the effect of strain on the exciton energy positions of the A-& B-excitons demonstrated that the experimental exciton energies couldn't be explained solely in terms of sample strain. We propose that electric fields in the samples due to charge trapping at grain boundaries are responsible for the additional perturbation of the excitons. This

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Electronic Processes in Zinc Oxide

Cited by 303 publications

References 83 publications

Whispering gallery modes in deformed hexagonal resonators

Whispering gallery modes in deformed hexagonal resonators

Photodegradation of m-cresol by Zinc Oxide under Visible-light Irradiation

Effect of polycrystallinity on the optical properties of highly oriented ZnO grown by pulsed laser deposition

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