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{\Large\bf
WWW Database of Optical Constants
}

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\vspace{0.2cm}

{\large Final Report}

\vspace{0.2cm}

({\it June 30, 1998})
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\noi {\bf 1$^0$.}
The optical constants of materials --
refractive index or dielectric permittivity --
are widely used in numerous scientific and engineering applications.
 These data are the input parameters necessary for any simulations of
the light scattering by dust grains and calculations of the
radiative transfer in various dusty media.
 Since the 60s the volume of such data measured
in laboratories has been permanently growing and
now it is not easy to overlook the results obtained
within about 40 years.

 We collected and classified most data available
and created a place in the Internet
for further accumulation of such data.
 The result of our work is the electronic Database of Optical Constants
which contains the data in different forms supplied by comments as well as
references to the papers on the subject and
links to various related Internet resources.
 This database has the access via Internet
(World Wide Web (WWW; White, 1993), anonymous FTP, etc.).

\bigskip
\noi {\bf 2$^0$.}
The work had been begun with the development of
the hierarchical structure of the WWW database.
 It is as follows: the database
has five levels from a Welcome HTML page (the uppermost level \#0)
down to HTML pages devoted to papers with the data (level \#4).
 Any page of the level \#4 corresponds to a paper and vice versa.
 Each page of the level \#3 contains a physical information on the material.
Any page of the level \#2 is related to a group of materials.
 Large tables on these pages
show all the data and papers collected for the group.
 The page of the level \#1 gives the links to the level \#2 pages
as well as to related topics.
 The page of the level \#0 describes the database.

\bigskip
\noi {\bf 3$^0$.}
The next step was the creation of a draft of
the main body of the WWW database.
It involved HTML pages corresponding to all the levels mentioned.
 These pages contained data tables and plots,
descriptions of source/reliability of the optical constants,
notices on the materials and papers,
and some general information about sources and Internet resources
available.

\bigskip
\noi {\bf 4$^0$.}
The created draft version of the WWW database
was installed on the server of
the Astrophysical Institute of the Jena University and
opened for a local use.
 After that, the general design of the database
and the content of its HTML pages were discussed by
various experts at the Jena University
and improvements of the database they suggested were made.
 Thus, the standards of the presentation of different kinds
of information in the WWW database were settled.

\bigskip
\noi {\bf 5$^0$.}
 To start with, we selected the solid materials of astronomical interest.
 They are as follows:

--  different kinds of amorphous/glassy/crystalline
  terrestrial/solar-system/artificial silicates;

--  crystalline/fused quartz; % (SiO, SiO$_2$)

--  metals: Fe, Mg, etc.;

--  oxides: FeO, Fe$_2$O$_3$, Fe$_3$O$_4$, MgO, Al$_2$O$_3$, SiO;

--  sulfides: FeS, MgS, SiS$_2$;

--  carbides: SiC, TiC;

--  carbonaceous species: amorphous carbon, glassy carbon,
    Hydrogenated Amorphous Carbon,
    coals, graphite, diamonds;

--  organics: tholin, kerogen, ``organic refractory";

--  H$_2$O, CO, CO$_2$, NH$_3$, HCN and other ices.

\bigskip
\noi {\bf 6$^0$.}
The search for the papers dealing with measurements of
the optical constants of the materials under consideration
was started with the Internet ADS database.
Other electronic databases were also looked for
abstracts of the recent works on the optical constants.
 All links to such abstracts appeared since the 50s were stored.
 The systematic search
was continued in the scientific libraries of St.~Petersburg.
A special work was also done in the libraries in Jena
 as some journals currently are not available in Russia.

 The final list of collected papers
contains more than 300 references to the  books, dissertations, papers
published from the 50s till 1998 and presenting
the optical constants measured or calculated
at the wavelength interval from X-rays to radio domain.
 In our opinion, all together we have comprised about 80-90\%
of such papers.

More than 200 of the collected papers,
including all not available in Russia were copied.
 Such a hard copy of the database allows easily to change it
if a modification becomes desirable.

\bigskip
\noi {\bf 7$^0$.}
The database developed has an extensive reference section.
It allows to
find required papers for each group of the materials considered.
 The section contains the tables whose columns show:
the material and its state (amorphous, crystalline, glassy,
hydrous, irradiated, etc.),
the quantity measured or calculated
(refractive index, dielectric permittivity, transmittance,
reflectance, extinction, mass absorption coefficient and so on),
the form of the data (table, figure, or both),
the wavelength range,
and the reference to the paper.

\bigskip
\noi {\bf 8$^0$.}
All together we have collected over 150 files with
the optical constants of various materials.
They were received in different ways and present:
own data (obtained in the laboratory
of the Astrophysical Institute of the Jena University),
data sent to us by authors or data open for free usage,
data scanned from the journals of the former Soviet Union
published before the Soviet Union has joined the
international copyright agreement in 1974, and
data scanned from other journals.
 Note that only for the latter, we need a permission of the copyright holders
in order to present the files for not only our personal use.
 This problem will be solved before the data will be used
in the database opened for public access.

\bigskip
\noi {\bf 9$^0$.}
A part of the data collected have been included in the database.
They were the optical constants obtained
in the laboratory of the Jena University as well as
the data derived
in the Soviet Union (before 1974) and some free data.

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., J\"ager et al. 1994, 1998;
Schnaiter et al. 1998).

 Many 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).
 However, these journals are not easily accessible.
 Therefore, it was worth to put
the data tables/figures in our database in the first turn.

\bigskip
\noi {\bf 10$^0$.}
  The data we included are both in table and graphic forms
and used to be supplied with information on
how the data were obtained,
what equipment was used and
what samples were considered.
 The data are given in their initial format (table or figure)
and in our standard format (table) and supplied with the plots:
refractive index vs wavelength and dielectric permittivity vs energy.

\bigskip
\noi {\bf 11$^0$.}
 The service codes we developed and added to the database allow
to transfer the data from our standard format to a desirable form
(refractive index or dielectric permittivity vs wavelength, wavenumber
or energy).
 Our scattering codes (Mie theory,
Separation of Variables Method for spheroids, T-Matrix Method and other codes)
give possibility
quickly to transform the data into the cross-sections, emissivity, and
so on.

\bigskip
\noi {\bf 12$^0$.}
The references to some general books and reviews on the subject
and links to Internet collections of optical data files and
personal WWW pages with related software were included in the database.
 First of all, among these resources one should mention
the WWW database of the optical constants in the X-ray domain and
the collections of the original data files for
ices at the Leiden University (see Ehrenfreund e.a. 1997 and references
therein),
%(http://...leiden.nl),
for carbonaceous species (see Zubko e.a. 1997 and references therein),
% (http://...),
and for water and water ice by P.J.~Flatau.
%(http://...), ...
 There are also useful tools of the Kramers-Kronig analysis
and the Effective Medium Theory available in WWW.

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.

\bigskip
\noi {\bf 13$^0$.}
The paper describing the database
(Th.Henning, V.B.Il'in, N.A.Krivova, B.Michel, N.V.Voshchinnikov
``WWW Database on Optical Constants for Astronomy")
has been completed
and will be submitted to the Astronomy \& Astrophysics Supplement.

\bigskip
\noi {\bf 14$^0$.}
We plan to continue filling in the database and developing its service.
Some additional tools now creating
should allow users easily to transfer to us
more references, data files, links, etc. to be included in the database.

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\bigskip
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\noi{REFERENCES}
\bigskip

\bitem {} Ehrenfreund P., Boogert A.C.A., Gerakines P.A. et al.
 1997, Astron. \& Astrophys.  328, 649

\bitem {} J\"ager C., Mutschke H., Begemann B., Dorschner J.,
Henning Th. 1994, Astron. \& Astrophys.  292, 641

\bitem {} J\"ager C., Mutschke H.,  Henning Th.
1998, Astron. \& Astrophys.  332, 291

\bitem {} Schnaiter M., Mutschke H., Dorschner J.,
Henning Th., Salama F. 1998, Astrophys. J. 498, 486

\bitem {} White B. 1993, in
Intelligent Information Retrieval: The Case of Astronomy
and Related Space Science. Eds. A.~Heck \& F.~Murtagh.
Kluwer Acad. Publ., p.127

\bitem {} Zolotarev V.M., Morozov V.N., Smirnova E.V.
1984, Optical constants of natural and technical media.
Leningrad, Khimija (in Russian)

\bitem {} Zubko V.G., Mennella V., Colangeli L. et al.
 1997, Monthly Notic. Royal. Astron. Soc. 282, 1321


\bigskip
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\newpage
\noi{\sf APPENDIX: How to navigate in the database}
\bigskip

Anyone can freely access the Database of Optical Constants.
Its Internet address is:
\mbox{\it http://www.astro.uni-jena.de/Users/database/0-entry.html}

 First, he 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 material groups (silicates, oxides and so on)
and a description of related topics (Internet resources, books, etc.).
 These and all other pages are written in the standard
 Hyper Text Markup Language (HTML).

Each group of materials has its own page.
It contains a table whose columns show:
the material and its state,
the quantity measured or calculated,
the form of the data,
the wavelength range (in microns),
and the reference to the paper.
 All the denotations used are explained
at the bottom of each page.

When the data in a paper were available
we created a corresponding WWW page
and supplied the reference table with a link to the page.
Such pages contain
links to the data and graphic files,
information about the paper with a link to its ADS abstract,
and a description of how the data were obtained.

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\begin{tabular}{ll}
Prof. Dr. Nikolai Voshchinnikov & \hspace{3cm} AIU\\
Representative of the Software  & \hspace{3cm} Friedrich Schiller
University\\
Development Group & \hspace{3cm} \\
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