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This study investigates the optical properties and microstructure of [Ta.sub.2][O.sub.5] film deposited with the glancing angle deposition technique. The tilted nanocolumn microstructure, examined with scanning electron microscopy, induces the optical anisotropy of thin film. The optical properties of thin film are characterized with an inverse synthesis method. Based on the Cauchy model, the dispersion equations of optical constants of film are determined from the transmittance spectra measured at normal and oblique incidence over 400-800 nm. The starting values derived with an envelope method quicken the optimization process greatly. The dispersion of the principal indices [N.sub.1], [N.sub.2], and [N.sub.3] and the thickness d of thin film are presented statistically. A good agreement between the measured optical properties and theoretical calculation is obtained, which validates the model established for thin film produced by glancing angle deposition. OCIS codes: 310.6860, 120.4530, 260.1440, 230.4000.

A method is proposed to evaluate the material dispersion of dielectric film in dielectric-coated silver hollow fiber. Cauchy's formulas that characterize the dispersion property were obtained for several commonly used dielectric materials by using the measured data of loss spectra of the hollow fibers. The wavelengths of the loss peaks and valleys in the loss spectra can be predicted more accurately when taking into consideration of the material dispersion. The derived Cauchy's formulas play an important role in the design of infrared hollow fiber for multiwavelength delivery. OCIS codes: 060.2280, 230.7370, 310.6860, 260.2030.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.03.001 Byline: Konstantinos S. Kalogerakis (a), Jochen Marschall (a), Anand U. Oza (a), Patricia A. Engel (a), Rhiannon T. Meharchand (a), Michael H. Wong (b) Keywords: Jupiter; atmosphere; Ices; IR spectroscopy; Jovian planets Abstract: We report laboratory experiments and modeling calculations investigating the effect of a hydrocarbon coating on ammonia ice spectral signatures. Observational evidence and thermochemical models indicate an abundance of ammonia ice clouds in Jupiter's atmosphere. However, spectrally identifiable ammonia ice clouds are found covering less than 1% of Jupiter's atmosphere, notably in areas of strong vertical transport, indicating a short lifetime for the signature of ammonia absorption on condensed ammonia particles [Baines, K.H., Carlson, R.W., Kamp, L.W., 2002. Icarus 159, 74-94]. Current literature has suggested coating of ammonia ice particles by a hydrocarbon haze as a possible explanation for this paradox. The work presented here supports the inference of a coating effect that can alter or suppress ammonia absorption features. In the experiments, thin films of ammonia ices are deposited in a cryogenic apparatus, coated with hydrocarbons, and characterized by reflection-absorption infrared spectroscopy. We have observed the effects on the ammonia ice absorption features near 3 and 9 [mu]m with coverage by thin layers of hydrocarbons. Modeling calculations of these multilayer thin films assist in the interpretation of the experimental results and reveal the important role of optical interference in altering the aforementioned ammonia spectral features. Mie and T-matrix scattering calculations demonstrate analogous effects for ammonia ice particles and investigate the relative effects of ammonia ice particle size, shape, and coating layer thickness on the ice particle spectral signatures. Author Affiliation: (a) Molecular Physics Laboratory, SRI International, Menlo Park, CA 94025, USA (b) Astronomy Department, University of California, Berkeley, CA 94720-3411, USA Article History: Received 19 December 2007; Revised 1 March 2008

Technology for the manufacture of coated glazings with spectrally selective optical properties, such as low-e and solar-control glazings, has been developed in the last few decades. This is leading researchers to develop new optical and thermal models in order to ascertain glazing performance. These new models must accurately reproduce the optical properties for any incident solar angle by using the available experimental data, which often means only information for normal incident radiation. In this paper, a new model is presented that characterizes the angular dependence of coated glazings. To provide a simple, intuitive understanding, this model uses only one thin film to characterize optical performance. In addition an optimization algorithm has been developed to obtain the spectral optical properties of that equivalent film using spectral experimental data under normal incidence. Finally, the model is validated with experimental data and the results are compared with other known models. Keywords: Thin films; Coated glazing; Optical properties

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solener.2005.08.004 Byline: Michael K.H. Leung (a), S.M. Tang (a), Ringo C.W. Lam (a), Dennis Y.C. Leung (a), W.C. Yam (b), S.P. Ng (b), Lilian L.P. Vrijmoed (c) Keywords: Solar; Photocatalytic; Parallel-plate photoreactor; Design optimization Abstract: This study focused on modeling and optimization of a photoreactor packed with parallel glass plates coated with sol-gel TiO.sub.2 thin films on both sides. The photoreactor design has great potential for solar photocatalytic air purification. Borosilicate glass substrate was selected because its high transmissivity facilitated the transmission and distribution of exterior solar radiation onto interior immobilized photocatalyst. Flat-plate configuration was adopted because a TiO.sub.2-coated plate could be easily set up for effective ion implantation treatment to extend the activating spectral range from UV to visible light for a higher solar photonic efficiency. In the analytical study of this research, a semi-empirical correlation model was formulated for prediction of the photoreactor performance. The correlation coefficients were obtained based on the results of photocatalytic air purification experiments conducted. Additional experimental tests were carried out for validation of the model. In the photoreactor design optimization analysis, the semi-empirical correlation model was used as an optimizer to determine the number of parallel TiO.sub.2-coated plates needed for efficient photocatalytic air purification. It was found that the optimal number of plates was dependent of the incident irradiance. The modeling and optimization methods developed for solar photocatalytic air purification are equally applicable for solar photocatalytic water purification. Author Affiliation: (a) Department of Mechanical Engineering, The University of Hong Kong, 7/F Haking Wong Building, Pokfulam Road, Hong Kong, China (b) Department of Microbiology, The University of Hong Kong, Hong Kong, China (c) Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, China Article History: Received 19 May 2005; Accepted 16 August 2005 Article Note: (miscellaneous) Communicated by: Associate Editor Gion Calzaferri

This paper presents a method for modeling the electromagnetic properties of thin metallic films typical of electromagnetically active food packages within multimode microwave applicators. A discontinuous sheet with six degrees of freedom (DOF) is incorporated within a time- or frequency-domain edge finite-element formulation by splitting the tetrahedral-element discretized domain on the thin-film surface and adding new DOF. Superior accuracy is observed when comparing with existing surface sheet conditions. Thermal image validation is provided for multimode applications. Index Terms--Finite edge element, metallic sheet, microwave package, thin conducting film.

We have studied the diffuse reflection properties of ceramics in the presence of dielectric thin films on the surface. A simple optical model was proposed in which interference effects in a thin film were considered for light scattered out of a ceramic in various directions. Measurements were performed on angle-resolved reflection spectra of a thin-film-coated alumina ceramic in the case of normal incidence. They showed that the presence of the thin film on the ceramic's surface modified the angular distributions of scattered radiation from that of a bare ceramic, which suggested a way to tailor the scattering properties of a diffuse reflector as needed. OCIS codes: 120.5700, 290.1990, 310.1620, 230.0250.

We present a novel experimental method to determine the switching field distribution in perpendicular thin-film magnetic recording media. The method assumes a constant demagnetization factor independent of the magnetic state during switching and a log-normal switching field distribution. The new technique allows a deconvolution of the effects of the switching field distribution and demagnetization, which is important for the development of low-noise perpendicular magnetic recording media. Index Terms--Magnetic characterization, magnetization reversal, perpendicular recording, switching field distribution.

The packet-like space-charge behavior in an oxidized crosslinked polyethylene (XLPE) film doped with antioxidant is discussed through computer simulation. The model is based on the following assumptions, (1) both electrons and holes are injected from the electrodes and they migrate to the opposite electrodes by hopping transport, (2) holes are also supplied from acceptor sites depending on the field, (3) the holes are excited to the hopping level only via an intermediate level. In this model, a space-charge packet is not caused by the excess of mobile electrons but by the deficiency in mobile holes. The ionized acceptors left behind by hole migration form an apparent negative space charge packet and it propagates towards the anode as the high field region moves.