WWW database of optical constants for astronomy
Th. Henning1, V.B. Il'in2, N.A. Krivova2, B. Michel1, N.V. Voshchinnikov2
1 Astrophysical Institute and University Observatory,
Friedrich Schiller University,
Schillergaesschen 3, D-07745 Jena, Germany
Published in Astron. Astrophys. Suppl. 136, 405 (1999)
It should be noted that the Jena data were intended especially for astronomical applications. They cover a wide spectral range, show the dependence on important parameters: Fe/Mg ratio, temperature, etc. Besides, well prepared samples and sophisticated control were used in these measurements (see, e.g., Jaeger et al., 1994; Jaeger et al., 1998; Schnaiter et al., 1998).
Several papers on the optical constants of the materials under consideration were published in former Soviet Union journals (see Zolotarev et al., 1984 for a review). As these journals are not easily accessible, we scanned the data tables/figures in the papers printed before 1974 (when the Soviet Union joined the international copyright agreement) and put them in our database.
The data we included are presented in their initial format (table or figure) and in our standard tabular format. In some cases we also give plots of the refractive index vs wavelength and dielectric permittivity vs energy dependences and an information on how the data were obtained, what equipment was used and what samples were considered.
The service codes of the database allow to transfer the data from our standard format to a desirable form (refractive index/dielectric permittivity vs wavelength/wavenumber/energy table with numbers of any format). Our light scattering codes based on Mie theory and Separation of Variables Method for spheroids give the possibility to transform the data into cross-sections, emissivity and so on. Palik, 1985, 1991) and links to Internet collections of optical data files and personal WWW pages with related software were also placed in the database.
First of all, among these Internet resources one should mention the WWW database of the optical constants in the X-ray domain created at the Lawrence Berkeley National Laboratory ( http://www-cxro.lbl.gov/optical_cons tants), and the collections of the data files obtained for a very large number of ice mixtures at the Leiden University (http://www.strw.leidenuniv.nl/~lab) and for amorphous carbon by V. Zubko (http://physics.technion.ac.il/~zubko/nk.html). There are also useful tools for the Kramers-Kronig analysis and Effective Medium Theory available in the World Wide Web.
Many light scattering codes have been developed and there are two general lists of such codes in the Internet. Besides links to these lists, we also give direct links to personal WWW pages where one can find most popular codes to simulate the electromagnetic radiation scattering by spheres (Mie theory), spheroids (Separation of Variables Method), axisymmetric particles (T-matrix Method), irregular-shaped particles (Discrete Dipole Approximation) and others. http://www.astro.spbu.ru/JPDOC/entry.html (server in St. Petersburg) or http://www.astro.uni-jena.de/Users/database/entry.html (server in Jena). First, one will arrive at a welcome WWW page with a short description of the database and a link to the database homepage. The latter includes our list of the material groups (silicates, oxides and so on) and a description of related topics (Internet resources, books, etc).
Each group of materials has its own page. It contains a table whose columns show: the state of material (amorphous, crystalline, glassy), the quantity measured or calculated (refractive index, reflectance, etc), the form of the data (table, figure), the considered wavelength range (in microns), and reference to the paper.
When the data in a paper were available we created a corresponding WWW page and supplied the table with a link to the page. Such pages can contain links to data and graphic files, information about the paper (e.g. its ADS abstract), a description of how the data were derived and so on. firstname.lastname@example.org.
Acknowledgements: The authors acknowledge the financial support of the Volkswagen Foundation (Germany) that made this work possible.