0 Titan: The Gem of the Saturnian System
• Atmosphere – 1.5 bar (thicker than Earth)
– 96% N2, 4% CH4
• Surface – Surface temperature is 94 K – Water-ice coated in organics (believed)
• Hydrologic Cycle: Vitally contribute to Titan’s geology and atmosphere. – Liquid methane, ethane lakes IR specularColorizedreflectionESA/NASA/JPL/University Mosiac off Jingpoof Titan’sLacus of lakes.captured Arizona NASA/JPL/USGS by Cassini VIMS – Methane clouds, rain (NASA/JPL/ Univ. of Arizona/DLR) 1 Why Study Titan?
1 Malaska and Hodyss 2014,Icarus 242,742 –81. Titan as a Prebiotic Laboratory
Titan is the only other place in our solar system that has standing liquid on its surface.
• It contains many organics that may lead to life. • Liquid is a good medium for molecule interaction. • No evidence of life yet. • Looking at Titan may help us gain insight on how life may have evolved on Earth.
Artist’s impression of Titan’s surface. Image by Ron Miller.
3 ‘More Titans than Earths’ Theory
• M-dwarf stars (red dwarfs) are ~100 times more common than yellow G-dwarf stars (our sun) • M-dwarfs are much less intense than G-dwarfs • Any planet far enough to be in asynchronous rotation with the star but not too cold will be more like Titan than Earth
J. I. Lunine, 2009, Proc. Amer. Phil. Soc., 153, 404-419. Planets orbiting a red dwarf. NASA/JPL-Caltech 4 The Argument for In Situ
An In Situ probe is necessary because Titan’s dense atmosphere obscures most remote observation.
5 Spectroscopy: A Nondestructive In Situ Technique
This technique is part of a set of analytical tools suitable for a Titan environment. Mid-IR is a good region for studying the bulk composition of the lakes. - Hydrocarbons like ethane, methane and propane have strong absorptions in this region. - Other organic molecules known or believed to be present include HCN,
acetylene, and CO2.
1 Malaska and Hodyss 2014,Icarus 242,746 –81. Objective
This study aims to understand Titanian hydrologic phenomena by mimicking native chemical reactions to those found on Titan including possible inclusion compound formations.
We also hope to develop a cryogenic spectral library in the Mid-IR of these compounds.
We work to develop a method of utilizing in situ spectroscopy suitable to study such an environment.
1 Malaska and Hodyss 2014,Icarus 242,747 –81. Inclusion Compounds
An inclusion compound is a complex of compounds in which a guest molecule is located within the cavity of a host molecule. Clathrates are inclusion compounds in which a guest molecule is trapped in a solid host molecule (cage). Cocrystals include multiple molecules within a crystal lattice. Molecules known to form inclusion compounds are present on Titan, therefore of interest to study to better understand the Titan environment.
Almarsson, Orn and Zaworotko, Michael J., 2004, Crystal engineering of the composition of pharmaceutical phases. Do pharmaceutical co-crystals represent a new path to improved medicines?, Chem. Commun. 17, 1889-1896
T.E. Gough, T.E. Rowat, and R. Illner, 1998, Modeling the Solid State Reaction CO2 C2H2 CO2 + C2H2, Chemical1 Physics Letters 298, 196-200 Malaska and Hodyss 2014,Icarus 242,748 –81. Equipment I/II
Spectrometer Nicolet 6700 FTIR, Thermo Scientific (1000-5000 cm-1) Probe Remspec Low Temperature Attenuated Total Reflectance (ATR) probe (625 to 16600 cm-1)
FTIR Spectrometer (Thermo Scientific)
Remspec ATR probe
9 Equipment II/II
Spectrometer Arcoptix FTIR-OEM000-ZnSe (714-5000 cm-1) Probe MultiLoop-MIR Silver Halide PIR (ATR) probe (2000 to 600 cm-1)
Arcoptix FTIR-OEM000-ZnSe MultiLoop ATR probe
10 ATR vs Transmission Probes
ATR (Attenuated Total Reflectance) probes allow for studying both transparent and opaque samples. They are hard, inert and allow for nondestructive analysis. ATR Transmission
0.5 – 10 mm
10 μm
Useful for: Useful for: • Solids • Clear Liquids
• Liquids 1 • Gases Malaska and Hodyss 2014,Icarus 242,7411 –81. • Gases ATR Probe Contact with Materials in Different States of Matter
Solid Saturated Evaporite Solution
12 MethodMethod First we did room temp for proof of concept then transitioned to a more native environment.
Cryo slides ATR probe Liquid ethane bath
Heater
Liquid nitrogen
© 2010 California Institute of Technology.
13 Method
Room Temperature • Hexamethylenetetramine (HMT) Cyanamide • Cyanamide HMT
Formaldehyde Cryogenic Temperature
• CO2 • Acetylene CO2 • Ethane • Ethylene Acetylene • Methane Methane • Paraformaldehyde Ethylene Ethane 14 Hexamethylenetetramine (HMT), (CH2)6N4 Nicolet FTIR, Room Temperature
CH 2 CH Stretch Bend
CN
Stretch Absorbance
CO Stretch OH Stretch CH3 OH Stretch Bend
15 Coated ATR Probe
1 Malaska and Hodyss 2014,Icarus 242,7416 –81. Cyanamide, CH2N2 Nicolet FTIR, Room Temperature
C≡N stretch
NH NH2 Stretch Deformation CN Stretch
(1250) Absorbance
OH CH3 OH CO Stretch Stretch Bend Stretch
17 1 Malaska and Hodyss 2014,Icarus 242,74–81. Cyanamide, CH2N2 Arcoptix, Room Temperature
NH CN Stretch Stretch (1250)
C≡N NH2 Stretch Deformation
OH CO Bend Stretch
OH CH3 Stretch Stretch
18 Cryogenic Experiments
CO2 Condensed on ATR Probe 1 Malaska and Hodyss 2014,Icarus 242,7419 –81. Ethane and Water Ice ARCOptix, Loop Probe
CH3 CC Deformation Stretch
OH Stretch
1 Malaska and Hodyss 2014,Icarus 242,7420 –81. Acetylene+CO2 ARCOptix Loop Probe
CO Asymmetric Stretch
21 Comparison to Published Data
Acetylene+CO2
T.E. Gough and T. Wang, 29 November 1994, Vibrational Spectroscopy of Cocrystallized Carbon Dioxide and Acetylene, J. 22 Chem. Phys. 102, 3932-3937 Comparison to Published Data
Acetylene+CO2
T.E. Gough and T. Wang, 29 November 1994, Vibrational 1 Spectroscopy of CocrystallizedMalaskaCarbon and Dioxide Hodyss and 2014,Icarus Acetylene, J. 242,7423 –81. Chem. Phys. 102, 3932-3937 Comparison to Published Data
Acetylene+CO2
T.E. Gough and T. Wang, 29 November 1994, Vibrational 1 Spectroscopy of CocrystallizedMalaskaCarbon and Dioxide Hodyss and 2014,Icarus Acetylene, J. 242,7424 –81. Chem. Phys. 102, 3932-3937 Ethylene+CO2 ARCOptix Loop Probe
CH2 Scissoring
CO Asymmetric Stretch
CH2 CH2 Wag Scissor
1 Malaska and Hodyss 2014,Icarus 242,7425 –81. Ethane and Paraformaldehyde ARCOptix, Loop Probe
CH3 CC Deformation Stretch
1 Malaska and Hodyss 2014,Icarus 242,7426 –81. Methane and Paraformaldehyde ARCOptix, Loop Probe
1 Malaska and Hodyss 2014,Icarus 242,7427 –81. Water Ice MultiLoop-MIR Loop Probe
Stoichiometric ratios might be critical for inclusion compound formation of some combinations.
Contact between species plays a role.
1 Malaska and Hodyss 2014,Icarus 242,7428 –81. Conclusion
Preliminary evidence for inclusion compound formation between paraformaldehyde and hydrocarbons.
Acetylene+CO2 require too specific of conditions to form a cocrystal in Titan conditions.
Evaporite/condensate is the best method because it has the most contact with samples, providing the strongest signal.
This has been verified both at room and cryogenic temperatures.
29 Future Work
Try Nicolet setup to observe acetylene+CO2 cocrystal formation in the 3500 cm-1 range.
Continue testing with Titan liquids, solids and evaporites as individual compounds and mixtures to develop a spectral library for future reference.
Try alternate techniques to examine possible paraformaldehyde+hydrocarbon inclusion compounds.
Try Raman IR, microscopy, and X-Ray diffraction of proposed inclusion compounds.
Mechanical engineering of the probe.
Goal is to include such a probe on a future Titan In Situ mission.
30 This work was supported by National Science Foundation grant #AST-1460538 to Los Angeles City College.
31 Contact: [email protected]
32 Backup Information
1 Malaska and Hodyss 2014,Icarus 242,7433 –81. Cassini – Huygens Mission
Studying the Saturn system for over 10 years Mission ends in 2017 Huygens Included suite of instruments Probe including imaging and mass spectrometers, radiometer provided information on Titan’s lake size and chemical composition. Huygens probe was launched in 2005 and collected a few hours of data as it descended into Titan’s atmosphere. Artists depiction of the Huygens probe launching from the Cassini mission. Landed in Aderi, in Titan’s equatorial region. Some info from Hubble and
Voyager. 34