Laboratory Studies on the Irradiation of Solid Ethane Analog Ices and Implications to Titan s Chemistry

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1 Laboratory Studies on the Irradiation of Solid Ethane Analog Ices and Implications to Titan s Chemistry 5th Titan Workshop at Kauai, Hawaii April 11-14, 2011 Seol Kim

2 Outer Solar System Model Ices with Ionizing Radiation Model Ices to investigate: Ethane ( H 6 in different morphology and temperatures Ammonia (NH 3 and methane (CH 4 ice system Ammonia (NH 3 and C n H 2n+2 (n = 1-6 ice system (a Radioylsis-induced products (b Production rates and yields (c Astrophysical implications (radiative transfer (1 Kim et al. ApJ 711, 744 (2010 (2 Kim & Kaiser ApJ 729, 68 (2011

3 Outer Solar System Model Ices with Ionizing Radiation Model Ices to investigate: Ethane ( H 6 in different morphology and temperatures Ammonia (NH 3 and methane (CH 4 ice system Ammonia (NH 3 and C n H 2n+2 (n = 1-6 ice system (a Radioylsis-induced products (b Production rates and yields (c Astrophysical implications (radiative transfer (1 Kim et al. ApJ 711, 744 (2010 (2 Kim & Kaiser ApJ 729, 68 (2011

4 Radiolysis-Driven Processing of Saturn s Satellites Enceladus Titan Cooper et al. Planet. Space. Sci. (2009 Lorenz et al. Geophys. Res. Lett. (2008

5 Laboratory Simulation: GCR-Induced Secondary Electrons 100 na, 1 hr: Fluence of electrons cm -2

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7 Electron Trajectories and Energy Loss: CASINO Code Probability Tranmitted Energy (kev NH 3 C n H 2n+2 (n = 1 6 Ices E trans (5 kev: 4.53 kev Linear Energy Transfer: 470 ev/129 nm or 3.6 kev/µm Radiation Dose: 3.8 ev molecule -1 (20 min, 1 µa

8 Infrared Spectra of Ethane ( H 6 Ice at 10 K Wavelength (µm Wavelength (µm ν Absorbance ν 5 ν 8 +ν 11 Absorbance ν 11 ν ν ν 2 +ν Wavenumber (cm -1 Wavenumber (cm -1 Thermally Amorphous Crystalline II Radiolytically

9 Phase Reversibility of Solid Ethane ( H 6 Thermally Wavelength (µm Radiolytically Wavelength (µm Absorbance K 28 K Absorbance after Irradiation at 30 K K Wavenumber (cm -1 Before Irradiation at 30 K Wavenumber (cm -1

10 Flux-Dependent Product Formation at 10 K Wavelength (µm ν 3 ( H 2 ν 3 (CH Wavelength (µm ν 9 ( H H 4 Absorbance na 20 na ν 10 ( H 5 Absorbance na H 8 CH4 H 8 H 8 H 4 H 2 H na na na Wavenumber (cm Wavenumber (cm -1 Major Products: Ethylene( H 4 and Butane ( Others: Ethyl Radical ( H 5, Acetylene ( H 2, Methane (CH 4, and Butene ( H 8

11 Ion Current Profiles during Warm-Up Phases Ethane (m/z=30 Blank 100 na Emission Currents (a E-7 (b E-7 1E-8 m/z = 30 1E-8 m/z = 30 1E-9 1E-9 Current (A 1E-10 1E-11 Current (A 1E-10 1E-11 1E-12 m/z = 16 1E-12 m/z = 16 1E-13 1E-13 m/z = Temperature (K Fragment due to EI ionization Temperature (K Product ion currents of methane (CH 4+ and butane ( + monitored

12 Temperature and Phase-dependent Yield CH 4 Temperature, K Amorphous 10 Crystalline 10 Crystalline 30 Crystalline 50 (1.5±0.2E15 (1.5±0.2E15 (1.4±0.3E15 (1.4±0.3E15 Solid Phase IR Column Density, molecule cm -2 Normalized, % Ion Charge, C (13.0±0.3E-10 (12.1±0.3E-10 (11.1±0.3E-10 (9.7±0.3E-10 Gas Phase QMS Normalized, % Amorphous 10 (9.9±1.4E (5.8±0.0E Crystalline 10 (9.2±1.7E15 93 (4.1±0.0E Crystalline 30 (7.6±1.4E15 77 (3.5±0.3E Crystalline 50 (6.3±1.1E15 64 (4.0±0.3E (Fluence of electrons cm -2 impinging on (1.3±0.1E17 molecules cm -2

13 Kinetic Model and Column Density Fits H 6 column density, cm E E E E E+017 H 6 10 K H 6 10 K H 6 30 K H 6 50 K 1.00E+017 CH 4 CH E E E+015 H 5 H 5 H 5 H 5 k 2 k 4 H 6 k 3 H 5 column density, cm E E E E+014 k E E+016 H 4 H 4 H 4 H 4 H 2 k 12 k 6 H 5 k 5 H k 7 H 2 column density, cm E E E E E H 2 H 8 H 4 H/H 2 k 8 H 4 column density, cm E E E+014 H 2 H 2 H 2 H E+014 H 3 H k E E+015 CH 4 CH 4 CH 4 CH 4 k 9 H 2 H/H 2 CH 4 column density, cm E E E E+000 X k 11 column density, cm E E E E E E H + H 6 k 13 C2 H 5 + H 2 H 8 column density, cm E E E+014 H 8 H 8 H 8 H E E Kim et al. ApJ 711, 744 (2010 time, minutes time, minutes time, minutes time, minutes

14 Energy Deposition of Titan Surface (ev cm -2 sec -1 4E-8 1E-8 solar min solar max Ground Level Scalar Muons (cm 2 sec MeV -1 1E-9 1E-10 1E-11 1E-12 1E-13 1E-14 π Φ = 2π 0 d(cosθ ψ ( Θ Φ( E Ed( E 0 1E Energy (GeV/Muon Lorenz et al. (2008 Energy flux (MeV cm -2 sec -1 Particle Solar minimum Solar maximum Muon Muon Gamma-ray Keran O Brien - NAU

15 Radiative Transfer to Titan Surface: Methane (CH 4 and Butane ( Production Rates Laboratory: ev cm -2 2E16 2E16 1/125 yrs 1E16 1E16 Column Density (cm -2 Titan Surface: 46 MeV cm -2 s -1 CH 4 Butane ( : kg cm -2 s -1 1E15 5E14 1E15 5E Temperature (K Methane (CH 4 : kg cm -2 s -1

16 Radiolysis-Induced Cyanide (CN - Formation at 10 K Wavelength (µm A ν 3 (NH 3 2ν 4 ν 1 NH 3 CH 4 NH 3 C n H 2n+2 (n = 1 6 ν 3 (CH 4 ν 4 (CH 4 a: ν 1 (CH 4 b: ν 2 +ν 4 (CH 4 c: 2ν 4 (CH 4 ν 4 (NH 3 ν 2 (NH Wavelength (µm B ν 3 (NH 3 2ν 4 ν 1 ν as (-CH 3 ν as (-CH 2 - ν s (-CH 3 δ as (-CH 3 δ(-ch 2 - ν 4 (NH 3 ν 2 (NH 3 δ s (-CH 3 a: H 6 ρ(-ch 2 - Absorbance d,e,f,g,h: H 6 a b c Absorbance a ν 3 (CH d e f δ(nh 2 ν 2 (CH ν 4 (CH 4 δ(nh 2 a: H 6 ω(=ch 2 g CN - h Wavenumber (cm -1 CN Wavenumber (cm -1 a

17 Temporal Evolution of CN - at 10 K 8.00E+015 A B C Scheme 6.00E µa 4.00E+015 A C Scheme column density, cm E E E E µa k 1 A NH 3 / C n H 2n+2 ; n =1-6 NH 3 / CH 4 -H -H NH 2 / CH E+015 k B: CH 3 NH E E time, minutes k 2 C -2H/H 2 CH 2 NH +Ba -2H/H 2 -HBa + CN -

18 Methylamine (CH 3 NH 2 Formation via Radical-Radical Recombination during Warm-up Gas Phase Wavelength (µm A Solid Phase (113 K 1E-7 1E-9 1E-11 A 1E-13 1E-7 B m/z=17 m/z=30 m/z=31 Absorbance CH 3 NH ν 3 (MA ν 12 /ν 5 (MA Wavenumber (cm -1 Kim & Kaiser ApJ 729, 68 (2011 Current (A 1E-9 1E-11 1E-13 1E-7 1E-9 1E-11 1E-13 1E-7 1E-9 1E-11 m/z=17 30,31 C m/z=30 D m/z=17 30,31 1E Temperature (K

19 Aminoacetonitrile (NH 2 CH 2 CN Production in Sgr B2(N Constrain the formation mechanism of Aminoacetonitrile (NH 2 CH 2 CN on Icy grains: Strecker-type synthesis CH 2 =NH + CN - + HBase + NH 2 CH 2 CN + Base vs. Radiolysis at as low as 10 K CH 2 =NH / H CN CH 2 =NH / H + CN CH 2 NH 2 / CN NH 2 CH 2 CN k 1 A NH 3 / C n H 2n+2 ; n =1-6 NH 3 / CH 4 -H -H NH 2 / CH 3 k Miao et al k 2 B: C CH 3 NH 2-2H/H 2 CH 2 NH +Ba -2H/H 2 -HBa + CN -

20 Acknowledgements