1 Modeling of the Light Scattering by Dust Particle Plasma near the Moon Surface G.V.Belokopytov, A.V.Zhuravlev M.V.Lomonosov Moscow State University, Dept. of Physics

October 10, 2012 The Third Moscow Solar System Symposium 2 Outline Introduction. Lunar dust levitation. Methods, have been used in lunar dust research Concentration of chemical elements and their optical properties Thin layer of non oxidizing iron on dust particles Size distribution of dust on the ground and above It Scattering type of lunar dust plasma in visible optical region and near IR.

October 10, 2012 The Third Moscow Solar System Symposium 3 Introduction. Lunar dust levitation.

October 10, 2012 The Third Moscow Solar System Symposium 4 Methods, have been used in lunar dust research Electronic microscopy Sedimentation Electrical charge measurement Impact measurement Single particle optical levitation ? LIDAR measurements

October 10, 2012 The Third Moscow Solar System Symposium 5 Concentration of chemical elements on the Moon Lunar dust consists not only from pure chemical elements but also from their compounds. Optical constants of elements and compounds may strongly differ.

October 10, 2012 The Third Moscow Solar System Symposium 6 Optical properties of main elements and their compounds Optical constants of elements and compounds comprising lunar dust strongly differ. [1] Johnson, Christy // Phys. Rev. B 1974, V.9, N.12 [2] Virgin semiconductors technical report // [3] Hagemann, Gudat, Kunz // DESY SR-74/7, 1974 [4] Malitson // J. Opt. Soc. Am., 1965, 55,

October 10, 2012 The Third Moscow Solar System Symposium 7 Scattering efficiencies of nanoparticles with different diameters Difference in optical constants leads to strongly different scattering efficiencies This in turn complicates optical measurement of nanoparticles concentrations and size distribution in dusty plasma Scattering efficiency Q sca - scattering crossection - radius of the particle Particle diameter D, nm example for =400 nm

October 10, 2012 The Third Moscow Solar System Symposium 8 Thin layer of non oxidizing iron Bibring, Durand, // Science V. 175, 1971, P. 753 Lunar dust have thin (approx. 100 nm) layer of non oxidizing iron Does they all have?

October 10, 2012 The Third Moscow Solar System Symposium 9 Two scattering types Dipolar Multipolar D << Easy to handle Uniform scattering in plane, perpendicular to E Almost independent scattering diagram on particle shape D  Difficult to handle The scattering diagram depends on particle shape strongly Nonuniform scattering diagram

October 10, 2012 The Third Moscow Solar System Symposium 10 Size distribution of lunar dust particles Liu,Taylor// NLSI Lunar Science Conference (2008 ) Diameter (  m) Apollo 11 Apollo 17 Apollo 16

October 10, 2012 The Third Moscow Solar System Symposium 11 There is estimation of particle distribution in levitating dust Golub’, Dol’nikov, Zakharov, et al. // JETP Lett., 2012, V. 95, N. 4, P. 182 Size distribution f(D)

October 10, 2012 The Third Moscow Solar System Symposium 12 Numerical Results. Determination of the scattering type all modes dipole modes on ground above ground Size distribution f(D) Averaged over size distribution scattering diameter

October 10, 2012 The Third Moscow Solar System Symposium 13 Conclusions There is background to suppose that the size distribution of levitating particles differs from one on the ground in the direction of decreasing diameters up to one order of magnitude. The scattering type of dusty plasma particles in visible and IR range is dipolar in case that mean diameter is about 10 nm, and multipolar when mean diameter is about 100 nm.

October 10, 2012 The Third Moscow Solar System Symposium 14 Conclusions The frequency and angular spectrum of scattered radiation is strongly dependent on the chemical composition of the lunar dust particles. Thin non oxidizing iron layer on certain portion of dust particles helps to decrease influence of variability of chemical composition. The concentration of particles with this layer should be investigated.

October 10, 2012 The Third Moscow Solar System Symposium 15 for your attention