AEROSOL SPECTROSCOPY FORASTROPHYSICAL DUST GRAININVESTIGATION
Oct. 8-10 2009
Grain Formation Workshop
Akemi Tamanai (AIU Jena & TU Braunschweig)
Harald Mutschke (AIU Jena)
Jürgen Blum (TU Braunschweig)
Alexander Krivov (AIU Jena)
Chiyoe Koike (Osaka Univerisy)

Factors to influence on MIR band profiles
Crystallinity
Polymorph （多形）同一物質が複数の異なった結晶構造を取る
e.g. SiO2
α-quartz(trigonal: 三方晶系)
α-tridymite(orthorhombic:斜方晶系)

α-cristobalite(tetragonal: 正方晶系)

Chemicalcompositon

Morphology
9 SizeMg, Fe, Al, Si, Ti,Ca, S, …
e.g. Olivine
San Carlos
Mg1.96Fe0.16Si0.89O4

9 Shape

Sri Lanaka
Mg1.56Fe0.40Si0.91O4

9 Agglomeration(Koike et al. 2003)

ExperimentSamples
Al2O3

Silicate
9 Forsterite (Mg2SiO4)
9 Fayalite (Fe0.64Si0.36O4)
9 Olivine (e.g. Mg1.96Fe0.16Si0.89O4)
9 Enstatite (MgSiO3)
9 Diopside (e.g. Ca0.45Mg0.54O0.99O3)
9 Hypersthene (e.g.Mg0.63Fe0.36Si0.9O3)
9 Wollastonite (CaSiO3)
9 Kaolinite (Al2Si2O7▪2H2O)
9 Talc (Mg3.33Fe0.1Si4O10 (OH)2)

9 Corundum (α-Al2O3)
9 γ-Al2O3
9 χ−δ−κ-Al2O3

MgAl2O4 (Spinel)
TiO2 (Rutile & Anatase)
CaTiO3 (Pervoskite)
Al2TiO5 (Tialite)
SiO2

www.elbe.uni-jena.de<Medium effect>εm

N2 Æ 1.0
KBr Æ 2.3
CsI Æ 3.0
The influence of its
electromagnetic polarization.
(Tamanai et al. 2009)

TiO2 (Rutile)
KBr :(Potassium Bromide)
Mixing ratio 1:500(sample:KBr)
d=13mm ; mass=0.2g

CsI :(Cesium Iodine)
Mixing ratio 1:500(sample:CsI)
d=13mm ; mass=0.22g

Aerosol vs. Pellet Measurements

Tamanai et al. (2009)• Using different dispersion methods• Particles may transform during the grinding procedure• Sample structure deformation caused by the high pressurization required• Particle orientation

<Morphological effects>
Irregular shapew/ rounded
edges
R1

Irregular shapewith notrounded edges
R2

Long and thin

R3

TiO2 (Rutile)
Rounded

R4(TEM & SEM images: at Pathology w/ Dr. Nietzsche)Peaks (microns)
R1
13.53
19.56
R215.33
R316.47 19.25
R413.85 19.27

24.70
23.51
23.39
25.15

30.30
27.95
28.27
35.8735.80

Morphological effect --- Size
¾ Extinction measurements of large-sized particles(2 – 50 μm)¾ Mixture measurements --- How small-sized particles
exert an influence on the extinction spectra when
they are present in a same environment with larger
ones (0.5 μm & 5 μm particles)

Cry-Mg2SiO4 (< 1μm)

Cry-Mg2SiO4 (~ 16 μm)

Amorphous SiO2 (d=0.5 & ~5 μm)

Aerosol generator
FTIR Spectrometer

FilterExp. 1 Large Particles (SiO2 monosphere)
1.2
Amo-SiO2 (Aerosol)
Normalized Extinction

1d~5.0 μm9.49 μm

8.93 μm

0.80.60.4
0.207Peaks

8910Log Wavelength [μm]208.93 μm 9.49 μm Δλ=0.56 μm
20.82 μm 21.21 μm Δλ=0.39 μm

Crystalline forsterite (Mg2SiO4)
1.2

3500

CsI 1:500
19.24
19.03

0.8 2500
10.15
9.87

κ (cm /g)

Normalized Extinction
2

1 3000

0.6

0.4

27.24
27.27

16.30
16.15

2000

Small particles
Large particles
Small particles
Large particles

23.22
23.25

11.15
11.08

33.65
33.19

1500

0.2

1000
08500910203040Log wavelength [μm]010203040• Size8Æ9Larger
Æ Longer wavelength
Log ofwavelength• The extinction strength
the 23 [μm]μm peak is enhanced.

Exp. 2 Mixture(monosphere vs. monosphere)

1Peaks (d=0.5μm (8.93μm) & d=5.0μm (9.49μm))
1:30 8.94μm 9.47μm
1:50 8.95μm 9.45μm
1:80 8.96μm 9.42μm
1:120 8.97μm 9.47μm

Qext(λ) / Qext(Peak)
NormalizedExtinction

0.8

1:30
1:50
1:80
1:120(c)

0.6

0.4

0.2

07.5

88.5

99.5

1010.511

1:120 Mag. 1K

Wavelength [μm](a)(b)1:80 Mag. 2K(d)1:80 Mag. 10K

1:120 Mag. 7K

Exp. 2 Mixture
1Qext(λ) / Qext(Peak)
Normalized
Extinction

0.8( monosphere vs. irregular shape)

Peaks (d=0.5μm (8.93μm) & d=5.0μm (9.49μm))

1:30 (Sphere)

Sphere Irregular Δλ1:30 8.94μm 8.95μm 0.01μm
9.47μm 9.17μm 0.30μm
1:50 8.95μm 8.96μm 0.01μm
9.45μm 9.20μm 0.25μm

1:50 (Sphere)
1:30 (Irregular)
1:50 (Irregular)

0.5 μm monosphere :crashed 5 μm particles

0.6¾ Survived 0.5 μmparticles show a clear
peak at 8.94 μm.

0.4

0.2

07.5

88.5

99.5

Wavelength [μm]

(a)

(b)

1010.5

11¾ The peak at 9.5 μm of
the 5 μm particles isstrongly influenced by
the morphologicalchanges (size &shape).

Summary<Aerosol vs. CsI pellet measurements>z Spherical or rounded particles produce larger difference between
the spectra compared to the irregular shaped particles.

<Morphological Effects>z Rounded grains tend to produce double peaked (rectangular)
profiles in comparison with irregular shaped grains.

<Large-sized particles vs. Small-sized particles (Forsterite)>z Peak positions are not strongly influenced by the particle size, but
the bandwidth beyond the 11 μm peak is significantly broadened.

<Mixture of Small- and Large-sized particles (SiO2)>

z Even mass of the 0.5 μm monosphere particles is 120x less thanthat of the 5 μm ones, the peak of the 0.5 μm particles clearly
appears on the extinction spectrum.