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Participant 6 (P6)
==================

Prof. A.Ya. Perel'man - St. Petersburg State Forest Technical Academy, RU

Dr. T.V. Wielgorskaya - Komarov's Botanical Institute, Russian Academy of
Sciences, St. Petersburg, RU and St. Petersburg State
Forest Technical Academy, RU

T.V. Zinov'eva - 23 years old; Astronomy Department, St. Petersburg
University, RU

Prof. Perel'man is a world-known expert in the light scattering theory and his
participation in the project is essential. Dr. Wielgorskaya is the author of
a widely used database in botany. The recent works of the team on the subject
of the project are as follows:

Task 1 (Light scattering theory)

An important approximation for optically soft particles (S-approximation or
Perel'man approximation) was developed in the paper of Perel'man ("Extinction
and scattering by soft particles." Appl. Opt., v. 30, 475, 1991). From this
approximation, other approximations like the Rayleigh, Rayleigh-Gans,
van de Hulst (anomalous diffraction) ones can be obtained.

The problem of light scattering by a spherical particle whose refractive index
arbitrarily depends on the distance from the particle center was solved by
Perel'man ("Scattering by particles with radially variable refractive index."
Appl. Opt., v. 35, 5452, 1996).

The method of conservation of the azimuthal structure of a perturbation in the
problems of diffraction by spherically symmetric scatterers (a phi-method)
was developed for an exact solution of the Mie problem and its generalizations
in the papers of Perel'man ("Integral presentation of field vectors in the
problem of diffraction by a sphere: I. General form of permissible waves in the
Mie problem." Opt. Spectrosc., v. 86, 105, 1999; "II. Phi-method of
solution of the boundary problem for Mie diffraction." Opt. Spectrosc., v. 86,
272, 1999).

The small angles S-approximations for the Stokes parameters were constructed by
Perel'man ("S-approximation for the Mie small angles amplitudes", Appl. Opt.,
1999, submitted). This approach allows the Hulst and Fraunhofer theories to be
developed, simultaneously. In particular, the new expression for the scattering
function can be treated both within the framework of the theory of anomalous
diffraction (generalization of the Hulst formulas for efficiencies) and the
Kirchhoff approximation. The latter is insensitive to the optical properties of
material while the expression obtained does take into account the dependence of
the scattering function on the refractive index of substance. This fact is of
particular importance in the astrophysical applications.

Task 3 (Electronic database)

The database of generic names of seed plants for botanic purposes was created
by Wielgorskaya ("Dictionary of generic names of seed plants." Columbia
University Press, New York, 1995). Later an electronic shell for this database
was made. The experience gained during this work will be used in the planned
development of the Database of Optical Properties.

Task 5 (Astrophysical applications)

The results obtained by Shifrin, Perel'man and Kokorin ("Optical properties of
particles of the complicated structure." J. Techn. Physics Lett., v. 11, 790,
1985; "Light scattering by two layers dielectric particles with continuous
optical properties." Opt. Spectrosc., v. 59, 597, 1985) allow one to essentially
improve the conventional scattering function of antireflection by large fluffy
particles of the interplanetary dust.

P6 team:

6.1. Shifrin K.S., Perel'man A.Ya., Kokorin A.M. (1985)
Optical properties of particles of the complicated structure.
Journal of Technical Physics Letters, v. 11, 790-794.

6.2. Shifrin K.S., Perel'man A.Ya., Kokorin A.M. (1985)
Light scattering by two layers dielectric particles with continuous optical
properties.
Optics & Spectroscopy, v. 59, 597-602.

6.3. Perel'man A.Ya. (1991)
Extinction and scattering by soft particles.
Applied Optics, v. 30, 475-484.

6.4. Perel'man A.Ya. (1994)
Improvement of the convergence of series for absorbing cross-section of a
soft sphere.
Optics & Spectroscopy, v. 77, 643-647.

6.5. Perel'man A.Ya. (1995)
Diffraction by spherically symmetric inhomogeneous scatterers.
Optics & Spectroscopy, v. 78, 741-750.

6.6. Wielgorskaya T.V. (1995)
Dictionary of generic names of seed plants.
Columbia University Press, New York, 570 pp.

6.7. Perel'man A.Ya. (1996)
Scattering by particles with radially variable refractive index.
Applied Optics, v. 35, 5452-5460.

6.8. Perel'man A.Ya. (1999)
Integral presentation of field vectors in the problem of diffraction by a
sphere: I. General form of permissible waves in the Mie problem.
Optics & Spectroscopy, v. 86, 105-114.

6.9. Perel'man A.Ya. (1999)
Integral presentation of field vectors in the problem of diffraction by a
sphere: II. Phi-method of solution of the boundary problem for Mie
diffraction.
Optics & Spectroscopy, v. 86, 272-287.