The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Hoyoung Kim - One of the best experts on this subject based on the ideXlab platform.
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visible light Absorptivity of a zincoxysulfide znoxs1 x composite semiconductor and its photocatalytic activities for degradation of organic pollutants under visible light irradiation
Applied Catalysis A-general, 2007Co-Authors: Cham Kim, Seok Joo Doh, Se Geun Lee, Sung Jun Lee, Hoyoung KimAbstract:Abstract This work reports the development of a visible-light sensible photocatalyst and the photocatalytic degradation of organic pollutants under visible-light irradiation. A composite semiconductor of ZnS and ZnO was prepared through co-precipitation process of Zn(NO3)2 in the mixed solution of aqueous Na2S and NaOH followed by calcination at 400 °C in N2 atmosphere. It was revealed that the composite semiconductor was a solid solution of ZnS and ZnO, a zincoxysulfide (ZnOxS1−x) having advanced visible-light Absorptivity. It was assured that the visible-light Absorptivity was caused by modification of band structure while the solid solution had been prepared, thus we suggested a reasonable band structure model involved in a zincoxysulfide. To observe its photocatalytic activity under visible-light illumination, photodegradation test was done and we confirmed that zincoxysulfide showed predominant photocatalytic activity due to its superior visible-light Absorptivity to pure ZnS and ZnO.
Alexander Kaplan - One of the best experts on this subject based on the ideXlab platform.
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Absorptivity modulation on wavy molten steel surfaces the influence of laser wavelength and angle of incidence
Applied Physics Letters, 2012Co-Authors: Alexander KaplanAbstract:The modulation of the angle-dependent Fresnel Absorptivity across wavy molten steel surfaces during laser materials processing, like drilling, cutting, or welding, has been calculated. The Absorptivity is strongly altered by the grazing angle of incidence of the laser beam on the processing front. Owing to its specific Brewster-peak characteristics, the 10.64 μm wavelength CO2-laser shows an opposite trend with respect to roughness and angle-of-incidence compared to lasers in the wavelength range of 532-1070 nm. Plateaus or rings of Brewster-peak Absorptivity can lead to hot spots on a wavy surface, often in close proximity to cold spots caused by shadow domains.
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local Absorptivity modulation of a 1 μm laser beam through surface waviness
Applied Surface Science, 2012Co-Authors: Alexander KaplanAbstract:Abstract In laser materials processing operations such as deep penetration laser welding, the laser beam often interacts with a wavy, molten surface. This wavy topology strongly modulates the local angle of incidence of the laser rays across the surface and in turn the local Absorptivity, which is described by the Fresnel-equations. In this paper this modulation of the Absorptivity is modelled over a two-dimensional steel surface for prescribed wavy topology for high power lasers with a wavelength of about 1 μm, like disc, fibre, Nd:YAG or diode lasers. It has become apparent that even a topology with regular peaks and valleys causes a complex Absorptivity distribution at the surface, including significant shadowing domains due to the grazing angle of incidence during processes like laser welding, drilling or cutting. In contrast to a smooth melt, the waviness tends towards an angle-averaged Absorptivity, of 33% for 1 μm-lasers and steel. The high sensitivity of the Absorptivity and of shadowing on the surface topology significantly modulates the local Absorptivity of the beam power density and in turn the local process mechanisms, such as boiling accompanied by recoil pressure.
Cham Kim - One of the best experts on this subject based on the ideXlab platform.
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visible light Absorptivity of a zincoxysulfide znoxs1 x composite semiconductor and its photocatalytic activities for degradation of organic pollutants under visible light irradiation
Applied Catalysis A-general, 2007Co-Authors: Cham Kim, Seok Joo Doh, Se Geun Lee, Sung Jun Lee, Hoyoung KimAbstract:Abstract This work reports the development of a visible-light sensible photocatalyst and the photocatalytic degradation of organic pollutants under visible-light irradiation. A composite semiconductor of ZnS and ZnO was prepared through co-precipitation process of Zn(NO3)2 in the mixed solution of aqueous Na2S and NaOH followed by calcination at 400 °C in N2 atmosphere. It was revealed that the composite semiconductor was a solid solution of ZnS and ZnO, a zincoxysulfide (ZnOxS1−x) having advanced visible-light Absorptivity. It was assured that the visible-light Absorptivity was caused by modification of band structure while the solid solution had been prepared, thus we suggested a reasonable band structure model involved in a zincoxysulfide. To observe its photocatalytic activity under visible-light illumination, photodegradation test was done and we confirmed that zincoxysulfide showed predominant photocatalytic activity due to its superior visible-light Absorptivity to pure ZnS and ZnO.
T Andert - One of the best experts on this subject based on the ideXlab platform.
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microwave Absorptivity by sulfuric acid in the venus atmosphere first results from the venus express radio science experiment vera
Icarus, 2012Co-Authors: Janusz Oschlisniok, Bernd Hausler, M Patzold, G L Tyler, M K Bird, Silvia Tellmann, S Remus, T AndertAbstract:Abstract The Venus Express (VEX) Radio Science experiment VeRa utilizes radio occultation techniques to investigate the Venus atmosphere over a wide range of latitudes. Radio attenuation measurements with the VEX 3.6 cm (X-band) signal provide information on the Absorptivity distribution within the Venus cloud deck. The combined results from 6 years of occultation measurements reveal a distinct latitudinal variation in Absorptivity in the altitude range from 50 to 55 km. Enhanced Absorptivity is observed at equatorial and mid-latitudes (0–50°S), exceeding 0.008 dB/km on the dayside and 0.01 dB/km on the nightside of the southern hemisphere. Poleward of 50°S latitude a decrease in the Absorptivity is observed, reaching minimal values at polar latitudes (>70°S), where the Absorptivity did not exceed 0.005 dB/km on the dayside and 0.004 dB/km on the nightside. The main absorber of radio waves in the Venus atmosphere, gaseous sulfuric acid, can serve as a tracer for atmospheric motions. The inferred Absorptivity was used to determine the abundance of gaseous sulfuric acid. Abundances of about 1–2 ppm are found between 0°S and 70°S latitude in the altitude range from 50 to about 52 km, sometimes increasing to values of about 3 ppm on the dayside and 5 ppm on the nightside near 50 km. The abundance at polar latitudes (>70°S) did not exceed 1 ppm within the considered altitude range. The Absorptivity and gaseous sulfuric acid height profiles are compared with previous measurements.
M K Bird - One of the best experts on this subject based on the ideXlab platform.
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microwave Absorptivity by sulfuric acid in the venus atmosphere first results from the venus express radio science experiment vera
Icarus, 2012Co-Authors: Janusz Oschlisniok, Bernd Hausler, M Patzold, G L Tyler, M K Bird, Silvia Tellmann, S Remus, T AndertAbstract:Abstract The Venus Express (VEX) Radio Science experiment VeRa utilizes radio occultation techniques to investigate the Venus atmosphere over a wide range of latitudes. Radio attenuation measurements with the VEX 3.6 cm (X-band) signal provide information on the Absorptivity distribution within the Venus cloud deck. The combined results from 6 years of occultation measurements reveal a distinct latitudinal variation in Absorptivity in the altitude range from 50 to 55 km. Enhanced Absorptivity is observed at equatorial and mid-latitudes (0–50°S), exceeding 0.008 dB/km on the dayside and 0.01 dB/km on the nightside of the southern hemisphere. Poleward of 50°S latitude a decrease in the Absorptivity is observed, reaching minimal values at polar latitudes (>70°S), where the Absorptivity did not exceed 0.005 dB/km on the dayside and 0.004 dB/km on the nightside. The main absorber of radio waves in the Venus atmosphere, gaseous sulfuric acid, can serve as a tracer for atmospheric motions. The inferred Absorptivity was used to determine the abundance of gaseous sulfuric acid. Abundances of about 1–2 ppm are found between 0°S and 70°S latitude in the altitude range from 50 to about 52 km, sometimes increasing to values of about 3 ppm on the dayside and 5 ppm on the nightside near 50 km. The abundance at polar latitudes (>70°S) did not exceed 1 ppm within the considered altitude range. The Absorptivity and gaseous sulfuric acid height profiles are compared with previous measurements.
