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
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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
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Introduction. Lunar dust levitation.
http://lunarscience.nasa.gov
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The Third Moscow Solar System Symposium
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Methods, have been used
in lunar dust research
Sedimentation
Electrical charge
measurement
Impact
measurement
?
Single particle
optical levitation
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The Third Moscow Solar System Symposium
Electronic
microscopy
LIDAR
measurements
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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.
http://www.permanent.com/l-apollo.htm
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The Third Moscow Solar System Symposium
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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 // http://www.virginiasemi.com/pdf/OpticalPropertiesofSilicon71502.doc
[3] Hagemann, Gudat, Kunz // DESY SR-74/7, 1974
[4] Malitson // J. Opt. Soc. Am., 1965, 55, 1205-1209
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The Third Moscow Solar System Symposium
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Scattering efficiencies of nanoparticles with
different diameters
Qsca 
Csca
 a2
C sca - scattering
crossection
a - radius
of the particle
Scattering efficiency Qsca
example
for l =400 nm
Particle diameter D, nm
• 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
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The Third Moscow Solar System Symposium
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Thin layer of non oxidizing iron
• Lunar dust have thin (approx. 100 nm) layer of non oxidizing iron
• Does they all have?
Bibring, Durand, // Science V. 175, 1971, P. 753
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The Third Moscow Solar System Symposium
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Two scattering types
Multipolar
Dipolar
E
E
k
k
H
H
D << l
• Easy to handle
• Uniform scattering in plane,
perpendicular to E
• Almost independent
scattering diagram on particle
shape
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D l
• Difficult to handle
• The scattering diagram
depends on particle shape
strongly
• Nonuniform scattering
diagram
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Size distribution of lunar dust particles
Apollo 11
Diameter (mm)
Apollo 17
Diameter (mm)
Apollo 16
Diameter (mm)
Liu,Taylor// NLSI Lunar Science Conference (2008)
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There is estimation of particle distribution in
levitating dust
f atm ( D)
Size distribution f(D)
f ( D)
2

1
ln( D)  ln( D0 ) 

f ( D) 
exp 
,
2
2
2 D




f atm ( D) 
B
f ( D)
3
D
Golub’, Dol’nikov, Zakharov, et al. // JETP Lett., 2012, V. 95, N. 4, P. 182
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Averaged over size distribution
scattering diameter <Dsca>
Numerical Results.
Determination of the scattering type
f ( D)
Size distribution f(D)
f atm ( D)
all modes
dipole modes
Dsca  2 Csca 
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on ground
above ground
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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.
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The Third Moscow Solar System Symposium
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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
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for your attention