Opacity Database (Aerosol)

Aerosol scattering and absorption can significantly affect the observed spectra of exoplanets and brown dwarfs. This page summarises the Mie scattering aerosol database included in POSEIDON.

Aerosol Database

POSEIDON v1.2 includes an extensive database of Mie scattering properties for atmospheric aerosols. The database and its computation are detailed in full in Mullens et al. (2024).

Species	Common Name (Name in POSEIDON)	Plot (Click)	Database Reference	Refractive Index References	Wavelength Range	Notes
\(\mathrm{\textbf{Super-Hot}}\)
\(\mathrm{CaAl_{12}O_{19}}\)	Hibonite (Hibonite)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Mutschke (2002) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Hibonite E||c)	2–30 μm	Crystalline (hexagonal, uniaxial) Natural Crystal (\(\mathrm{Ca_{0.85}Al_{11.37}Ti_{0.26}Fe_{0.38}O_{19}}\)) Extraordinary (E||c) used
\(\mathrm{Al_{2}O_{3}}\)	\(\gamma\) Corundum (Al2O3)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Koike et al. (1995)	0.34–30 μm	Crystalline (cubic, isotropic) Both Alumina and ISAS (combustion product) used
\(\mathrm{Al_{2}O_{3}}\)	Corundum (Al2O3_KH)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Begemann et al. (1997) Koike et al (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Porous)	0.2–30 μm	Mix of amorphous alumina (porous, isotropic) + \(\gamma\) crystalline corundum (cubic, isotropic, ISAS)
\(\mathrm{CaTiO_{3}}\)	Perovskite (CaTiO3)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Posch (2003) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (CaTiO3)	2–30 μm	Crystalline (orthorhombic, near-cubic and isotropic) Natural Crystal
\(\mathrm{CaTiO_{3}}\)	Perovskite (CaTiO3_KH)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Posch (2003) Ueda (1998) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (CaTiO3)	0.2–30 μm	Crystalline (orthorhombic, near-cubic and isotropic) Natural Crystal + Synthetic Single Crystal
\(\mathrm{\textbf{M-L Dwarf}}\)
\(\mathrm{TiO_{2}}\)	Anatase (TiO2_anatase)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Zeidler (2011) Posch (2003) Siefke (2016) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Anatase)	0.2–30 μm	Crystalline (tetragonal, uniaxial) Natural Anatase (\(\mathrm{Ti_{0.992}V_{0.008}O_{2}}\)) + Thin Film Natural crystal indices averaged by polarization (2/3 Ordinary + 1/3 Extraordinary)
\(\mathrm{TiO_{2}}\)	Rutile (TiO2_rutile)		gCMCRT \(\hookrightarrow\) GitHub	Ribarsky in Palik (1985) [Vol 1, Sec 39] (C) Zeidler (2011) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Rutile, E||a,b)	0.47–30 μm	Crystalline (tetragonal, uniaxial) Natural Rutile (\(\mathrm{Ti_{0.984}V_{0.008}Fe_{0.008}O_{2}}\)) Ordinary (E||a,b) used
\(\mathrm{TiC}\)	Titanium Carbide (TiC)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Koide (1990) Henning & Dutschke (2001)	0.2–30 μm	Crystalline (cubic, face centered, isotropic) Synthetic Single Crystals
\(\mathrm{VO}\)	Vanadium Oxide (VO)		gCMCRT \(\hookrightarrow\) GitHub	Wan et al. (2019)	0.3–30 μm	\(\mathrm{VO_2}\) thin film as a VO proxy (\(\mathrm{VO_2}\) is monoclinic, uniaxial but thin film is random orientation)
\(\mathrm{C}\)	Meteoritic Nano-Diamonds (NanoDiamonds)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Mutschke (2004)	0.2–30 μm	Crystalline (cubic, isotropic) Natural Crystal
\(\mathrm{\textbf{Iron}}\)
\(\mathrm{Fe}\)	\(\alpha\) Iron (Fe)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Lynch & Hunter in Palik (1991) (Vol 2, Sec 15) (C)	0.2–30 μm	Crystalline (cubic, body centered, stil slightly anisotropic due to ferromagnetism)
\(\mathrm{FeO}\)	Wüstite (FeO)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Begemann (1995)	0.21–30 μm	Crystalline (Cubic, face centered, isotropic) Synthetic
\(\mathrm{FeS}\)	Troilite (FeS)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Pollack (1994) (C) Henning & Mutschke (1997) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (FeS)	0.2–30 μm	Crystalline (Hexagonal, grows as an isotropic slab) Natural + Synethic crystal
\(\mathrm{Fe_2O_3}\)	Hematite / \(\alpha \mathrm{Fe_2O_3}\) (Fe2O3)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Unpublished, Triaud in DOCCD \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Fe2O3 E||a,b)	0.2–30 μm	Crystalline (Rhombohedral, uniaxial) Ordinary ray (E||a,b) used
\(\mathrm{FeSiO_3}\)	Ferrosilite (FeSiO3)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Day (1981)	8.22–30 μm	Amorphous (isotropic) Iron-rich olivine
\(\mathrm{Fe_2SiO_4}\)	Fayalite (Fe2SiO4_KH)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Fabian (2001) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Fayalite (synthetic))	0.40–30 μm	Crystalline (orthorhombic, biaxial) Synthetic Single Crystal Each polarization (E||c,b,a) averaged
\(\mathrm{\textbf{Magnesium}}\)
\(\mathrm{MgO}\)	Periclase (MgO)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Roessler & Huffman in Palik (1991) (Vol 2, Sec 46) (C)	0.2–30 μm	Crystalline (cubic, isotropic) KH18 filled empty Palik entries with Kramers-Kronig analysis or spline interpolation
\(\mathrm{Mg_{0.8}Fe_{1.2}SiO4}\)	Forsterite ‘Iron-rich’ (Mg2SiO4_Fe_rich)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Henning (2005) (C) Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(0.8)Fe(1.2)SiO4)	0.21–30 μm	Amorphous (glass, isotropic) Olivine
\(\mathrm{Mg_{1.72}Fe_{0.21}SiO4}\)	Forsterite ‘Iron-poor’ (Mg2SiO4_Fe_poor)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Zeidler (2011) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (San Carlos Olivine)	0.2–30 μm	Crystalline (orthorhombic, biaxial) Natural crystal Extraordinary ray (E||c) used Olivine
\(\mathrm{Mg_{2}SiO4}\)	Forsterite (Mg2SiO4_amorph)		Burningham (2021)	Jager (2003) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(2)SiO(4))	0.27–30 μm	Amorphous Sol Gel (synthetic, isotropic)
\(\mathrm{Mg_{2}SiO4}\)	Forsterite (Mg2SiO4_amorph_sol_gel)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Jager (2003) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(2)SiO(4))	0.2–30 μm	Amorphous Sol Gel (synthetic, isotropic)
\(\mathrm{Mg_{2}SiO4}\)	Forsterite (Mg2SiO4_crystalline)		gCMCRT \(\hookrightarrow\) GitHub	Suto (2006)	0.2–30 μm	Crystalline (orthorhombic, biaxial) Synthetic Single Crystals E||a and E||b polarizations combined Olivine
\(\mathrm{MgFeSiO_4}\)	Olivine (MgFeSiO4_amorph_glass)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (MgFeSiO[4] [3.71 g/ccm])	0.2–30 μm	Amorphous (glass, isotropic) Synthetic
\(\mathrm{Mg_{0.8}Fe_{1.2}SiO_4}\)	Olivine (Mg8Fe12SiO4_amorph_glass)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(0.8)Fe(1.2)SiO4)	0.2–30 μm	Amorphous (glass, isotropic) Synthetic
\(\mathrm{MgSiO_3}\)	Enstatite (MgSiO3)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Egan & Hilgeman (1975) Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (MgSiO(3) [2/71 g/ccm])	0.2–30 μm	Natural Crystalline (orthorhombic, biaxial) (no polarization given) + Synthetic Amorphous (glass, isotropic) Silicate pyroxene
\(\mathrm{MgSiO_3}\)	Enstatite (MgSiO3_amorph)		Burningham (2021)	Scott & Duly (1996) (C) Draine & Lee (1984) Nitsan & Shankland (1976)	0.27–30 μm	Amorphous Enstatite Thin Film (isotropic) + ‘Astronomical’ Silicate (observation derived) + Crystalline Synthetic Forsterite (E||a + E||c) Refractive indices from 0.06-62 μm, interpolated to fit EGP grid (0.26-227 μm) Silicate pyroxene
\(\mathrm{MgSiO_3}\)	Enstatite (MgSiO3_amorph_glass)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (MgSiO(3) [2/71 g/ccm])	0.2–30 μm	Amorphous (glass, isotropic) Synthetic Silicate pyroxene
\(\mathrm{MgSiO_3}\)	Enstatite (MgSiO3_sol_gel)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Jager (2003) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (MgSiO(3))	0.2–30 μm	Amorphous Sol Gel (synthetic, isotropic) Silicate pyroxene
\(\mathrm{MgSiO_3}\)	Ortho-Enstatite (MgSiO3_crystalline)		Burningham (2021)	Jager (1998) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Enstatite (natural))	0.27–30 μm	Crystalline (Orthorhombic, biaxial) Natural crystal with some talc formations Each polarization (E||c,b,a) averaged Refractive indices from 2-99 μm, interpolated to fit EGP grid (0.26-227 μm) Silicate pyroxene
\(\mathrm{Mg_{0.4}Fe_{0.6}SiO_3}\)	Pyroxene (Mg4Fe6SiO3_amorph_glass)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(0.4)Fe(0.6)SIO(3))	0.2–30 μm	Amorphous (glass, isotropic) Synthetic Silicate pyroxene
\(\mathrm{Mg_{0.5}Fe_{0.5}SiO_3}\)	Pyroxene (Mg5Fe5SiO3_amorph_glass)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(0.5)Fe(0.5)SIO(3) [3.2 g/ccm])	0.2–30 μm	Amorphous (glass, isotropic) Synthetic Silicate pyroxene
\(\mathrm{Mg_{0.8}Fe_{0.2}SiO_3}\)	Pyroxene (Mg8Fe2SiO3_amorph_glass)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Dorschner (1995) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Mg(0.5)Fe(0.5)SIO(3) [3.2 g/ccm])	0.2–30 μm	Amorphous (glass, isotropic) Synthetic Silicate pyroxene
\(\mathrm{MgAl_2O_4}\)	Spinel (MgAl2O4)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Fabian (2001) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Natural Mg-spinel)	1.69–30 μm	Crystalline (cubic, isotropic) Natural (\(\mathrm{Mg_{1.02}Al_{1.93}Fe_{0.01}Cr_{0.01}O_4}\)) Annealed at 1223K for one hour, induces a disordered phase transition
\(\mathrm{\textbf{Silica}}\)
\(\mathrm{SiC}\)	Moissanite / \(\alpha\) Carborundum (SiC)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Laor & Draine (1993) (C) Philipp & Taft (1960) in Caras (1965) Bohren & Huffman (1983) [Sec 9.1, 12.3.4]	0.2–30 μm	Crystalline (cubic, isotropic). Lab data + Dampled Oscillator Fit
\(\mathrm{SiO}\)	Silicon Monoxide (SiO)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Philipp in Palik (1985) (Vol 1, Sec 36) (C) Wetzel (2013)	0.2–30 μm	Amorphous (glass, isotropic) Palik Compilation + Thin Film KH18 filled empty Palik entries with spline interpolation
\(\mathrm{SiO_2}\)	\(\alpha+\beta\) Quartz (SiO2)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Philipp in Palik (1985) (Vol 1, Sec 34) (C) Zeidler (2013) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (SiO2 at 928K, E||c)	0.2–30 μm	Short wavelengths is \(\alpha\) Quartz (crystalline, trigonal, uniaxial) Infrared wavelengths is \(\beta\) Quartz (crystalline, hexagonal, uniaxial) 928K, Extraordinary (E||c) ray was used for \(\beta\) Quartz
\(\mathrm{SiO_2}\)	\(\alpha\) Quartz (SiO2_crystalline_2023)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Herve Herbin & Petitprez (2023)	0.25–15.37 μm	Crystalline (trigonal, uniaxial) Airborne quartz particles, random orientation
\(\mathrm{SiO_2}\)	\(\alpha\) Quartz (SiO2_alpha_palik)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Philipp in Palik (1985) (Vol 1, Sec 34) (C)	0.2–30 μm	Crystalline (trigonal, uniaxial) Variety of lab sources Kramers-Kronig analysis was utilized to fill in empty Palik entries \(\hookrightarrow\) pyElli (Kramers-Kronig code) Indices averaged by polarization (2/3 Ordinary + 1/3 Extraordinary)
\(\mathrm{SiO_2}\)	\(\alpha\) Quartz + Silica Glass (SiO2_amorph)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Henning & Mutschke (1997) Philipp in Palik (1985) (Vol 1, Sec 34) (C) \(\hookrightarrow\) DOCCD Link \(\hspace{1.0em}\) (Amorphous SiO2, 300K)	0.2–30 μm	Short wavelengths is \(\alpha\) Quartz (crystalline,trigonal,uniaxial) Long wavelengths is amorphous silica (glass, isotropic)
\(\mathrm{SiO_2}\)	Silica Glass (SiO2_glass_palik)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Philipp in Palik (1985) (Vol 1, Sec 34) (C)	0.2–30 μm	Amorphous (glass, isotropic) Kramers-Kronig analysis was utilized to fill in empty Palik entries \(\hookrightarrow\) pyElli (Kramers-Kronig code)
\(\mathrm{\textbf{T-Y Dwarf}}\)
\(\mathrm{Cr}\)	Chromium (Cr)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Lynch & Hunter in Palik (1991) (Vol 2, Sec 15.6) (C) Rakic (1998)	0.2–30 μm	Crystalline (cubic, body centered, isotropic) (technically tetragonal, but not by much) Palik compiled lab data + computed from first principles
\(\mathrm{MnS}\)	\(\alpha\) Manganese Sulfide (MnS)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Huffman & Wild (1967)	0.2–13 μm	Crystalline (cubic, isotropic) Synthetic single crystals
\(\mathrm{MnS}\)	\(\alpha\) Manganese Sulfide (MnS_KH)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Huffman & Wild (1967) Montaner (1979)	0.2–30 μm	Crystalline (cubic, isotropic) Synthetic single crystals + \(\mathrm{Na_2S}\) extrapolation
\(\mathrm{MnS}\)	\(\alpha\) Manganese Sulfide (MnS_Mor)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Huffman & Wild (1967) Montaner (1979)	0.2–30 μm	Crystalline (cubic, isotropic) Synthetic single crystals + \(\mathrm{Na_2S}\) extrapolation Used WS15 indices to 13 μm, and KH18 from 13-30 μm
\(\mathrm{Na_2S}\)	Sodium Sulfide (Na2S)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Morley (2012) Montaner (1979) Khachai (2009)	0.2–30 μm	Crystalline (cubic, face centered, isotropic) Compiled by Morley (2012) Synthetic crystal lab data (15K) + computed from first principles
\(\mathrm{ZnS}\)	Zinc blende / Sphalerite (ZnS)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Querry (1987)	0.22–30 μm	Crystalline (cubic, isotropic) High purity sample
\(\mathrm{NaCl}\)	Halite / Rock Salt (NaCl)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Eldridge & Palik in Palik (1985) (Vol 1, Sec 38) (C)	0.2–30 μm	Crystalline (cubic, isotropic) WS15 would assume constant imaginary index to fill in empty Palik entries (causes step-function-like cross section)
\(\mathrm{KCl}\)	Sylvite (KCl)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Palik in Palik (1985) (Vol 1, Sec 33) (C)	0.2–30 μm	Crystalline (cubic, isotropic) WS15 would assume constant imaginary index to fill in empty Palik entries (causes step-function-like cross section)
\(\mathrm{\textbf{Ices}}\)
\(\mathrm{NH_4H_2PO_4}\)	Ammonium Dihydrogen Phosphate (ADP)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Zernike (1965) Querry (1974)	0.2–19.99 μm	Crystalline (tetragonal, uniaxial) + Liquid Synthetic crystal + aqueous solution Crystalline indices averaged by polarization (2/3 Ordinary + 1/3 Extraordinary)
\(\mathrm{H_2O}\)	Water (liquid) (H2O)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Hale & Querry (1973) (C)	0.2–30 μm	Room temperature (298.5K) liquid water
\(\mathrm{H_2O}\)	Ice 1h (H2O_ice)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Warren (1984) (C)	0.2–30 μm	Crystalline (hexagonal, uniaxial) (266.15K ice) No ordinary or extraordinary indices listed
\(\mathrm{NH_4SH}\)	Amonnium Hydrosulfide (NH4SH)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Personal Communication \(\hookrightarrow\) Howett (2007) (C)	0.5–30 μm	Crystalline (rhombic, biaxial) (~160K) Unpublished dataset, personal communication.
\(\mathrm{NH_3}\)	Amonnia (NH3)		optool \(\hookrightarrow\) Github	Martonchik (1984) (C)	0.2–30 μm	Crystalline (cubic, isotropic) Synthetic thin film (77-88K)
\(\mathrm{CH_4}\)	Methane (liquid) (CH4_liquid)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Martonchik & Orton (1984) (C)	0.2–30 μm	111K Liquid Methane Refractive index data is sometimes absolute lower or upper limit
\(\mathrm{CH_4}\)	Methane (solid) (CH4_solid)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Martonchik & Orton (1984) (C)	0.2–30 μm	Crystalline (cubic, isotropic) 90K Solid Methane Refractive index data is sometimes absolute lower or upper limit
Ice Tholins	Ice Tholins — see notes (IceTholin)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Khare (1993)	0.2–30 μm	Amorphous (isotropic) \(\mathrm{C_2H_6}\)/\(\mathrm{H_2O}\) (1:6 ratio) irradiation residue (77K)
\(\mathrm{\textbf{Soots and Hazes}}\)
\(\mathrm{C}\)	Graphite (C)		Kitzmann & Heng (2018) \(\hookrightarrow\) GitHub	Draine (2003) Draine (2003)	0.2–30 μm	Crystalline (hexagonal, uniaxial) Indices averaged by polarization (2/3 Ordinary + 1/3 Extraordinary)
ExoHaze	ExoHaze — see notes (ExoHaze_1000xSolar_300K)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	He et al. (2023)	0.4–28.6 μm	Amorphous (isotropic) 66% H2O, 6.6% CH4, 6.5% N2, 4.9% CO2, and 16% He irradiation residue
ExoHaze	ExoHaze — see notes (ExoHaze_1000xSolar_400K)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	He et al. (2023)	0.4–28.6 μm	Amorphous (isotropic) 56% H2O, 11% CH4, 10% CO2, 6.4% N2, 1.9% H2, and 14.7% He irradiation residue
\(\mathrm{C}\)	Flame Soot (Soot)		gCMCRT \(\hookrightarrow\) GitHub	Lavvas & Koskinen (2017) (C)	0.2–30 μm	Amorphous (isotropic) Lavvas & Koskinen (2017) used Kramers-Kronig analysis on extant lab data for soots
\(\mathrm{C_6H_{12}}\)	1-Hexene (Hexene)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Anderson (2000)	2–25 μm	Liquid (linear alpha olefin)
\(\mathrm{H_2SO_4}\)	Sulfuric Acid (H2SO4)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Palmer & Williams (1975)	0.36–24.98 μm	Liquid (300K, 84.5% solution) 0.702-0.360 μm imaginary indices fit with an exponent 2.564-2.770 μm fit with an exponent and offset to match data
\(\mathrm{S_8}\)	Cyclo-Octasulfur / Orthorhombic Sulfur / \(\alpha\) Sulfur (S8)		gCMCRT \(\hookrightarrow\) GitHub	Fuller, Downing, & Querry in Palik (1998) (Vo 3, Sec 42) (C)	0.2–30 μm	Crystalline (orthorhombic, biaxial) Palik only records ‘ordinary ray’ (averaged E||a and E||b)
Saturn Haze	Saturn Phosphorus Haze — see notes (Saturn-Phosphorus-Haze)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Noy (1981) Fletcher (2023) Sromovsky (2019)	0.2–20 μm	Amorphous (isotropic) Diphosphine haze proxy Imaginary indices from Noy (1981) and Fletcher (2023) Real from Sromovsky (2019) (white phosphorus)
\(\mathrm{C}\)	Soot 6mm — see notes (Soot_6mm)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Chang & Charalampopoulos (1990)	0.2–28.4 μm	Amorphous (isotropic) Optical indices measured 6mm above burner
Titan Tholin	Tholin — see notes (Tholin)		Wakeford & Sing (2015) \(\hookrightarrow\) Link	Khare (1984) Ramirez (2002)	0.2–30 μm	Amorphous (isotropic) Both tholin references are \(\mathrm{N2}\) - \(\mathrm{CH_4}\) irradiation residue Khare (1984) is 9:1 and Ramirez (2002) is 9.8:0.2 Ramirez (2002) indices are used from 0.2-0.4 μm due to issues in Khare (1984)
Oxygenated Tholin	Tholin C/O=1 — see notes (Tholin-CO-1)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Corrales (2023)	0.2–9.99 μm	Amorphous (isotropic) \(\mathrm{N2}\) - \(\mathrm{CH_4}\) - \(\mathrm{CO_2}\) (C/O = 1, 9:0.5:0.5) irradiation residue
Oxygenated Tholin	Tholin C/O=0.625 — see notes (Tholin-CO-0625)		Mullens et al. (2024) \(\hookrightarrow\) GitHub	Corrales (2023)	0.2–9.99 μm	Amorphous (isotropic) \(\mathrm{N2}\) - \(\mathrm{CH_4}\) - \(\mathrm{CO_2}\) (C/O = 0.625, 9:0.8:0.2) irradiation residue

(C) refers to references that compile refractive index data (sometimes to supplement their own lab data). See Aerosol-Database-Readme.txt for more details.

Refractive indices are room temperature unless specifically noted.

Plots display refractive indices (real and imaginary) (x represents actual refractive indices, line is interpolated), effective extinction cross section (combined scattering and absorption) for mean particle sizes (1e-3 to 10 μm) assuming a lognormal particle distribution with a width of 0.5. Median asymmetry parameter and single scattering albedo for mean particle sizes (1e-3 to 10 μm) assuming a lognormal particle distribution with a width of 0.5.

Short summaries on each refractive index paper, as well as when you would expect each aerosol to form with planetary-specific references for each entry and class, are listed in aerosol_database_readme.txt.

Please address any request for new aerosols to: eem85@cornell.edu.

Optional: Aerosol Directionality + Temperature Dependence Database

POSEIDON v1.3.1 includes an optional database of Mie scattering properties for minerals with their directionality and temperature dependent properties. By default, this database is not included in POSEIDON’s input files. You can download it from Zenodo: Optional Aerosol Files.

After downloading the files, please put them in your inputs/opacity folder.

The database and its computation are detailed in full in Mullens et al. (2025) [submitted].

Note that the species in this table cannot be used in conjunction with the normal aerosol database in a forward model.

The below compared sub-micron (0.01 um) effective, extinction cross sections of the drectional/temperature dependent aerosols to their counterparts in the normal aerosol database.

For full previews of extinction cross sections and scattering properties of each aerosol, see

“Directional Opacity Previews”

For a detailed table, see

“Directional LaTeX Table”

All refractive index txt files can be found in

“Directional Refractive Indices”

Also see the new tutorial (as of V1.3.1):

“Aerosols Advanced: Directionality”

Species	Name in POSEIDON	Plot (Click)	Refractive Index References	Wavelength Range	Notes
\(\mathrm{CaAl_{12}O_{19}}\) Directional Properties (Uniaxial)	CaAl12O19_crystal_natural_extraordinary (E \(\parallel\) c) CaAl12O19_crystal_natural_ordinary (E \(\perp\) c)		Mutschke (2002) \(\hookrightarrow\) DOCCD Link	2–30 μm	Crystalline (hexagonal, uniaxial) Natural Crystal (\(\mathrm{Ca_{0.85}Al_{11.37}Ti_{0.26}Fe_{0.38}O_{19}}\))
\(\mathrm{Al_{2}O_{3}}\) Porous vs Compact	Al2O3_amorph_compact Al2O3_amorph_porous		Begemann (1997) \(\hookrightarrow\) DOCCD Link	7.81–30 μm	Amorphous (isotropic).
\(\mathrm{Al_{2}O_{3}}\) Directional and Temperature Properties (Uniaxial)	Al2O3_alpha_crystal_300K_ordinary (E \(\perp\) c) Al2O3_alpha_crystal_551K_ordinary (E \(\perp\) c) Al2O3_alpha_crystal_738K_ordinary (E \(\perp\) c) Al2O3_alpha_crystal_928K_ordinary (E \(\perp\) c) Al2O3_alpha_crystal_300K_extraordinary (E \(\parallel\) c) Al2O3_alpha_crystal_551K_extraordinary (E \(\parallel\) c) Al2O3_alpha_crystal_738K_extraordinary (E \(\parallel\) c) Al2O3_alpha_crystal_928K_extraordinary (E \(\parallel\) c)		Zeidler (2013) \(\hookrightarrow\) DOCCD Link	6.67–30 μm	Crystalline (trigonal, uniaxial) Synthetic Crystal
\(\mathrm{MgAl_{2}O_{4}}\) Annealed	MgAl2O4_crystalline_natural MgAl2O4_crystalline_natural_annealed_1223K		Fabian 2001 \(\hookrightarrow\) DOCCD Link	2–30 μm (1.67–30 μm for annealed)	Crystalline (cubic, isotropic) Natural crystal
\(\mathrm{MgAl_{2}O_{4}}\) Temperature Properties	MgAl2O4_synthetic_10K MgAl2O4_synthetic_100K MgAl2O4_synthetic_300K MgAl2O4_synthetic_551K MgAl2O4_synthetic_738K MgAl2O4_synthetic_928K		Zeidler (2013) \(\hookrightarrow\) DOCCD Link	6.71–30 μm (7.70–30 μm for 10K, 100K)	Crystalline (cubic, isotropic) Natural crystal
\(\mathrm{Fe_{2}SiO_{4}}\) Directional Properties (Biaxial)	Fe2SiO4_crystal_synthetic_Ez (E \(\parallel\) c) Fe2SiO4_crystal_synthetic_Ey (E \(\parallel\) b) Fe2SiO4_crystal_synthetic_Ex (E \(\parallel\) a)		Fabian (2001) \(\hookrightarrow\) DOCCD Link	2–30 μm	Crystalline (orthorhomboc, biaxial) Synthetic crystal Orthorhombic means the optical axes align with the crystallographic axes Original text does not specify how x,y,z correspond to c,b,a so we assume it follows the D2H symmetry group (Ez = B1U = Ec, Ey = B2U = Eb, Ex = B3U = Ea)
\(\mathrm{TiO_{2}}\) Polymorphs and Directional Properties (Uniaxial/Biaxial)	TiO2_anatase_ordinary (E \(\perp\) c) TiO2_anatase_extraordinary (E \(\parallel\) c) TiO2_rutile_ordinary (E \(\perp\) c) TiO2_rutile_extraordinary (E \(\parallel\) c) TiO2_brookite_Ez (E \(\parallel\) c) TiO2_brookite_Ey (E \(\parallel\) b) TiO2_brookite_Ex (E \(\parallel\) a)		Posch (2003) Zeidler (2011) \(\hookrightarrow\) DOCCD Link	2–30 μm (0.47–30 μm for rutile)	Anatase (tetragonal, uniaxial, stable at room temperature) Rutile (tetragonal, uniaxial, stable at high temperatures) Brookite (orthorhombic, biaxial, rare polymorph at room temperatures) Orthorhombic means the optical axes align with the crystallographic axes Original text does not specify how x,y,z correspond to c,b,a so we assume it follows the D2H symmetry group (Ez = B1U = Ec, Ey = B2U = Eb, Ex = B3U = Ea)
\(\mathrm{SiO_{2}}\) Polymorphs, Directional, and Temperature Properties (Uniaxial)	SiO2_alpha_crystal_300K_ordinary (E \(\perp\) c) SiO2_alpha_crystal_551K_ordinary (E \(\perp\) c) SiO2_alpha_crystal_738K_ordinary (E \(\perp\) c) SiO2_alpha_crystal_833K_ordinary (E \(\perp\) c) SiO2_beta_crystal_928K_ordinary (E \(\perp\) c) SiO2_alpha_crystal_300K_extraordinary (E \(\parallel\) c) SiO2_alpha_crystal_551K_extraordinary (E \(\parallel\) c) SiO2_alpha_crystal_738K_extraordinary (E \(\parallel\) c) SiO2_alpha_crystal_833K_extraordinary (E \(\parallel\) c) SiO2_beta_crystal_928K_extraordinary (E \(\parallel\) c) SiO2_alpha_crystal_300K_averaged (2/3 E \(\perp\) c + 1/3 E \(\parallel\) c) SiO2_beta_crystal_928K_averaged (2/3 E \(\perp\) c + 1/3 E \(\parallel\) c)		Zeidler (2013) \(\hookrightarrow\) DOCCD Link	6.26–30 μm	\(\alpha\) Quartz (trigonal, uniaxial, room temperature polymorph) \(\beta\) Quartz (trigonal, uniaxial, transforms from \(\alpha\) quartz at ~850K) Natural crystal from Brazil. We include opacities for when refractive indices are averaged before Mie calculations WARNING: We reccomend using opacities seperate, than these averaged opacities, as averaging refractive indices before precomputation can shift absorption features.
\(\mathrm{SiO_{2}}\) Polymorphs, and Temperature Properties	SiO2_alpha_crystal_A2_295K (E \(\parallel\) c) SiO2_alpha_crystal_E_295K (E \(\perp\) c) SiO2_alpha_crystal_E_346K (E \(\perp\) c) SiO2_alpha_crystal_E_480K (E \(\perp\) c) SiO2_alpha_crystal_E_600K (E \(\perp\) c) SiO2_alpha_crystal_E_705K (E \(\perp\) c) SiO2_alpha_crystal_E_790K (E \(\perp\) c) SiO2_beta_crystal_E_1010K (E \(\perp\) c) SiO2_beta_crystal_E_1125K (E \(\perp\) c) SiO2_beta_crystal_E_1170K (E \(\perp\) c) SiO2_beta_crystal_E_1310K (E \(\perp\) c) SiO2_beta_crystal_E_1394K (E \(\perp\) c) SiO2_beta_crystal_E_1520K (E \(\perp\) c) SiO2_beta_crystal_E_1590K (E \(\perp\) c) SiO2_beta_crystal_E_1646K (E \(\perp\) c) SiO2_beta_cristobalite_E_1810K SiO2_beta_cristobalite_E_1880K		Meneses (2014)	6.67–30 μm	\(\alpha\) Quartz (trigonal, uniaxial, room temperature polymorph) \(\beta\) Quartz (trigonal, uniaxial, transforms from \(\alpha\) quartz at ~850K) \(\beta\) Cristobalite (cubic, isotropic, transforms from \(\beta\) quartz at ~1750K) Cut crystal. Note that these indices were only measured for the ordinary ray (E), with the exception of the single extraordinary measurement (A2). Also note that cristobalite is isotropic while the other polymorphs are uniaxial.
\(\mathrm{SiO_{2}}\) Polymorphs, and Temperature Properties	SiO2_alpha_cristobalite_295K SiO2_beta_tridymite_295K SiO2_beta_tridymite_500K		Moran (2024)	0.30–15 μm	\(\alpha\) Cristobalite (tetragonal, uniaxial, transforms from \(\beta\) cristobalite that has been rapidly quenched) \(\beta\) Tridymite (hexagonal, uniaxial, transforms from \(\beta\) quartz (w/ impuritied) at ~1150K) Wavelengths for some indices were extrapolated from other datasets. See original paper for details.
\(\mathrm{Mg_{2}SiO_{4}}\) Directional and Temperature Properties (Biaxial)	Mg2SiO4_295K_B1U (E \(\parallel\) c) Mg2SiO4_546K_B1U (E \(\parallel\) c) Mg2SiO4_950K_B1U (E \(\parallel\) c) Mg2SiO4_1102K_B1U (E \(\parallel\) c) Mg2SiO4_1147K_B1U (E \(\parallel\) c) Mg2SiO4_1431K_B1U (E \(\parallel\) c) Mg2SiO4_1518K_B1U (E \(\parallel\) c) Mg2SiO4_1648K_B1U (E \(\parallel\) c) Mg2SiO4_1742K_B1U (E \(\parallel\) c) Mg2SiO4_1809K_B1U (E \(\parallel\) c) Mg2SiO4_295K_B2U (E \(\parallel\) b) Mg2SiO4_547K_B2U (E \(\parallel\) b) Mg2SiO4_720K_B2U (E \(\parallel\) b) Mg2SiO4_946K_B2U (E \(\parallel\) b) Mg2SiO4_1122K_B2U (E \(\parallel\) b) Mg2SiO4_1303K_B2U (E \(\parallel\) b) Mg2SiO4_1417K_B2U (E \(\parallel\) b) Mg2SiO4_1535K_B2U (E \(\parallel\) b) Mg2SiO4_1617K_B2U (E \(\parallel\) b) Mg2SiO4_1818K_B2U (E \(\parallel\) b) Mg2SiO4_295K_B3U (E \(\parallel\) a) Mg2SiO4_602K_B3U (E \(\parallel\) a) Mg2SiO4_757K_B3U (E \(\parallel\) a) Mg2SiO4_918K_B3U (E \(\parallel\) a) Mg2SiO4_1055K_B3U (E \(\parallel\) a) Mg2SiO4_1131K_B3U (E \(\parallel\) a) Mg2SiO4_1256K_B3U (E \(\parallel\) a) Mg2SiO4_1503K_B3U (E \(\parallel\) a) Mg2SiO4_1793K_B3U (E \(\parallel\) a) Mg2SiO4_1948K_B3U (E \(\parallel\) a) Mg2SiO4_295K_averaged (1/3 E \(\parallel\) c,b,a) Mg2SiO4_1000K_averaged (1/3 E \(\parallel\) c,b,a)		Eckes (2013)	2.5–30 μm	Crystal (orthorhombic, biaxial) Synthetic Orthorhombic means the optical axes align with the crystallographic axes It is defined that B1U = Ec, B2U = Eb, B3U = Ea (pers. comm) We include opacities for when refractive indices are averaged before Mie calculations WARNING: We reccomend using opacities seperate, than these averaged opacities, as averaging refractive indices before precomputation can shift absorption features.
\(\mathrm{Mg_{1.9}Fe_{0.1}SiO_{4}}\) Directional Properties (Biaxial)	Mg19Fe01SiO4_crystal_natural_Ex (E \(\parallel\) c) Mg19Fe01SiO4_crystal_natural_Ey (E \(\parallel\) b) Mg19Fe01SiO4_crystal_natural_Ez (E \(\parallel\) a)		Zeidler (2011) \(\hookrightarrow\) DOCCD Link	2–30 μm	Crystalline (orthorhombic, biaxial) Natural Crystal (Stubachtal) Orthorhombic means the optical axes align with the crystallographic axes While DOCCD does not explictly label their axes, we assume its the same as Mg172Fe021SiO4: Ex = Ec, Ey = Eb, and Ez = Ea.
\(\mathrm{Mg_{1.72}Fe_{0.21}SiO_{4}}\) Directional Properties VIS/NIR Wavelengths (Biaxial)	Mg172Fe021SiO4_crystal_visnir_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_visnir_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_visnir_Ez (E \(\parallel\) a)		Zeidler (2015) \(\hookrightarrow\) DOCCD Link	0.32–6.99 μm	Crystalline (orthorhombic, biaxial) Natural Crystal (San Carlos) Orthorhombic means the optical axes align with the crystallographic axes As stated on DOCCD, we assume: Ex = Ec, Ey = Eb, and Ez = Ea.
\(\mathrm{Mg_{1.72}Fe_{0.21}SiO_{4}}\) Directional and Temperature Properties (Biaxial)	Mg172Fe021SiO4_crystal_10K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_100K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_200K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_300K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_551K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_738K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_928K_Ex (E \(\parallel\) c) Mg172Fe021SiO4_crystal_10K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_100K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_200K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_300K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_551K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_738K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_928K_Ey (E \(\parallel\) b) Mg172Fe021SiO4_crystal_10K_Ez (E \(\parallel\) a) Mg172Fe021SiO4_crystal_100K_Ez (E \(\parallel\) a) Mg172Fe021SiO4_crystal_200K_Ez (E \(\parallel\) a) Mg172Fe021SiO4_crystal_300K_Ez (E \(\parallel\) a) Mg172Fe021SiO4_crystal_551K_Ez (E \(\parallel\) a) Mg172Fe021SiO4_crystal_738K_Ez (E \(\parallel\) a) Mg172Fe021SiO4_crystal_928K_Ez (E \(\parallel\) a)		Zeidler (2015) \(\hookrightarrow\) DOCCD Link	6.71–30 μm	Crystalline (orthorhombic, biaxial) Natural Crystal (San Carlos) Orthorhombic means the optical axes align with the crystallographic axes As stated on DOCCD, we assume: Ex = Ec, Ey = Eb, and Ez = Ea.
\(\mathrm{Mg_{0.92}Fe_{0.09}SiO_{3}}\) Directional and Temperature Properties (Biaxial)	Mg092Fe009SiO3_crystal_10K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_100K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_200K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_300K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_551K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_738K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_928K_Ez (E \(\parallel\) c) Mg092Fe009SiO3_crystal_10K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_100K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_200K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_300K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_551K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_738K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_928K_Ex (E \(\parallel\) b) Mg092Fe009SiO3_crystal_10K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_100K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_200K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_300K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_551K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_738K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_928K_Ey (E \(\parallel\) a) Mg092Fe009SiO3_crystal_300K_averaged (1/3 E \(\parallel\) c,b,a) Mg092Fe009SiO3_crystal_928K_averaged (1/3 E \(\parallel\) c,b,a)		Zeidler (2015) \(\hookrightarrow\) DOCCD Link	6.71–30 μm	Crystalline (orthorhombic, biaxial) Natural Crystal (Burma) Orthorhombic means the optical axes align with the crystallographic axes As stated on DOCCD, we assume: Ex = Eb, Ey = Ea, and Ez = Ec.

Optional: Diamond Database

POSEIDON v1.3.1 also includes an optional database of Mie scattering properties for diamonds. By default, this database is not included in POSEIDON’s input files. You can download it from Zenodo: Optional Aerosol Files.

After downloading the files, please put them in your inputs/opacity folder.

For full previews of extinction cross sections and scattering properties of each aerosol, see “Diamond Opacity Previews”

All refractive index txt files can be found “Diamond Refractive Indices”

Note that the entry ‘NanoDiamonds’ (meteoric diamonds, detailed above in the normal aerosol database) is also included in this database, for convenience.

Name in POSEIDON	Plot (Click)	Database Reference	Refractive Index References	Wavelength Range	Notes
Diamond_palik		Ohno (2024)	Palik (1985) [Vol 1] (C)	0.2-6.5 μm	Crystalline (cubic, isotropic) Pure Diamond
Hydrogentated_Diamond_fH0_N0_irradiated Hydrogentated_Diamond_fH0_N0_not_irradiated Hydrogentated_Diamond_fH025_N0_irradiated Hydrogentated_Diamond_fH025_N0_not_irradiated Hydrogentated_Diamond_fH1_N0_irradiated Hydrogentated_Diamond_fH1_N0_not_irradiated		Ohno (2024)	Jones (2012a) Jones (2012b) Jones (2012c) Jones (2012d) Jones (2012e) Jones (2022a) Jones (2022b)	0.2-30 μm	Crystalline (cubic, isotropic) 6 samples of hydrogenated diamonds f_H = fraction of hydrogenation (0, 0.25, and 1) Irradiated and non-irradiated by cosmic-rays

Optional: \(\mathrm{SiO_2}\) Free Lognormal Logwidth Database

POSEIDON v1.3.1 also includes a database of Mie scattering properties for \(\mathrm{SiO_2}\) where the lognormal logwidth (used in the lognormal distribution) is a free parameter. By default, this database is not included in POSEIDON’s input files. You can download it from Zenodo: Optional Aerosol Files.

After downloading the files, please put them in your inputs/opacity folder.

Also see the updated tutorial (as of V1.3.1) to see how to make and use this database: “Making an Aerosol Database”.