University of Northern Iowa
March 6 & 7, 2015
Midwest Astrochemistry Meeting 2015
Schedule of Events
Friday, 6 March 2015
4:30-5:30 PM Dr. Ricardo Arevalo, Jr., Research Space Scientist at NASA Goddard Space Flight
Center, will present “IT’S A TRAP! A REVIEW OF THE MOMA INSTRUMENT ABOARD
EXOMARS 2018, AND OTHER ION TRAPS IN SPACE OR UNDER DEVELOPMENT”. He
will speak in Room 201, McCollum Science Hall. Refreshments will be available at 3:30 PM.
6:00-9:00 PM The poster session will be held in the lounge outside MSH201. Posters may be
hung after 5:00 PM. Pizza and beverages will be available starting around 6:30 PM.
Saturday, 7 March 2015
Oral sessions will be held in Room 201, McCollum Science Hall. The building entrances should
be unlocked by 8:00 AM. The first session will begin at 8:45 AM. There will be a mid-morning
break with coffee and snacks, and lunch will be provided in the form of box lunches. The
meeting is scheduled to adjourn around 1:30 PM.
Parking
The Chemistry and Biochemistry Department is located on the top floor of McCollum Science
Hall (#43 on the campus map). If needed, there is a dock available at the east end of McCollum
Science Hall for unloading. Free parking is available in the “A” lot after 4 PM as noted on the
map. It is a short walk to McCollum Science Hall from the parking lot. See campus map on
next page. There will be time between the seminar at 4 PM and the poster session for people who
arrive early to go check in at their hotels.
See maps for building and parking lot locations.
Friday Keynote Talk
IT’S A TRAP! A REVIEW OF THE MOMA INSTRUMENT ABOARD
EXOMARS 2018, AND OTHER ION TRAPS IN SPACE OR UNDER
DEVELOPMENT
Dr. Ricardo Arevalo, Jr.
NASA Goddard Space Flight Center
Recently, ion trap mass spectrometers have found a niche as small, versatile alternatives to
traditional quadrupole mass analyzers, capable of in situ characterization of planetary
environments and the search for organic matter. The Rosetta space probe, which was built and
launched by ESA in March 2004 and became the first spacecraft to orbit a comet in August 2014,
successfully landed the Philae robotic lander carrying the first planetary ion trap on comet
67P/C-G in November 2014. The 2018 mission of the ESA ExoMars Program will deliver a
European rover equipped with the next ion trap dedicated to planetary exploration: the Mars
Organic Molecule Analyzer (MOMA). The MOMA instrument represents an international
collaboration between NASA and ESA, and the core astrobiological experiment of the entire
ExoMars Program. The heart of the MOMA instrument is a 2D (or “linear”) ion trap designed to
facilitate two symmetrical ion injection pathways, thereby enabling both laser desorption mass
spectrometry (LDMS) at Mars ambient pressures and traditional gas chromatography mass
spectrometry (GCMS) techniques. These two complementary modes of operation empower
MOMA with an unprecedented ability to detect both volatile and refractory organic molecules, in
addition to providing geochemical context through the measurement of inorganic signatures of
sample mineralogy. In particular, the analysis of nonvolatile higher molecular weight organics,
even in the presence of perchlorate, has been demonstrated on multiple breadboard platforms and
the flight-like engineering test unit (ETU). In light of the demonstrated proficiencies of these
instruments, significant resources have been invested to develop a series of even more capable
ion traps for future spaceflight applications; examples include the development by GSFC of an
enhanced Linear Ion Trap Mass Spectrometer (LITMS) with negative ion detection and core
sampling compatibility; the Mass Analyzer for Real-time Investigation of Neutrals at Europa
(MARINE) pioneered by JPL; and, the evolution of a high-resolution (up to m/Δm = 1E5; full
width at half maximum, or FWHM) Orbitrap mass analyzer for spaceflight, as advanced by the
French Orbitrap Consortium.
Poster Session – 6 March 2015
P1. A Continuous Supersonic Expansion Discharge Source for HighPrecision Mid-Infrared Spectroscopy of Cold Molecular Ions
Courtney N. Talicska, Mike W. Porambo, and Benjamin J. McCall
P2. A Continuous Supersonic Expansion Discharge Source for HighPrecision Mid-Infrared Spectroscopy of Cold Molecular Ions High
Precision Spectroscopy of Molecular Ions Relevant to the Interstellar
Medium
Charles R. Markus, Adam Perry, James Hodges, G. Stephen Kocheril, and
Benjamin McCall
P3. Analysis of Rotationally Resolved C3 using Updated Oscillator
Strengths
Nicole C. Koeppen, and Benjamin J. McCall
P4. Exploring Titan’s Atmospheric Chemistry Through Laboratory
Simulations
Angela Weepie, Quentin Pavic, and Dr. Joshua Sebree
P5. The Measuring of Cosmic Rays During a High-Altitude Balloon Flight
Michael Madsen, Bawa Sadjifo, Kyle Spurgeon, Elizabeth Turcotte, Angela
Weepie, Alex Oberle and John Ophus
P6. ADMIT: ALMA Data Mining Toolkit
Douglas N. Friedel, Leslie W. Looney, Lisa Xu, Marc W. Pound, Peter J.
Teuben, Kevin P. Rauc3, Lee G. Mundy, and Jeffrey S. Kern
P7. Impact of Laboratory Studies of the C + H3+ Reaction on Astrochemical
Models
Shreyas Vissapragada, Daniel Wolf Savin
Schedule for Oral Session – 7 March 2015
T1. (Open Forum, 8:45-9:15) The NASA Postdoctoral Program and other
Early Career opportunities at NASA.
Joshua A. Sebree
(9:15-9:30) Break
T2. (9:30-9:50) CARMA 1 CM Line Survey of Orion-KL
Douglas N. Friedel, Leslie W. Looney, Anthony J. Remijan, and Joanna
Corby
T3. (9:50-10:10) Determining the Chemistry of Super-Earth Exoplanet
Atmospheres
Eliza Kempton
T4. (10:10-10:30) Clouds in Super-Earth Atmospheres - Equilibrium
Chemistry Calculations
Rostom Mbarek, Eliza Kempton
(10:30-10:45) Break
T5. (10:45-11:05) Low temperature HD + ortho-/para-H2 inelastic scattering
of astrophysical interest
Renat A. Sultanov
T6. (11:05-11:25) Exploring Pathways to Nitrogen Containing
Heteroaromatics is Titan’s Atmosphere: Spectroscopy of Cyanostyrene
Isomers
Joseph A. Korn, Stephanie N. Knezz, Robert J. McMahon, and Timothy S.
Zwier
T7. (11:25-11:45) Spectroscopic analysis of Titan Analog Aerosols
Angela Weepie, Quentin Pavic, and Joshua Sebree
(11:45-1:00) Lunch/Closing
Poster Abstracts
A Continuous Supersonic Expansion Discharge Source for HighPrecision Mid-Infrared Spectroscopy of Cold Molecular Ions
Courtney N. Talicska, Mike W. Porambo, and Benjamin J. McCall
Department of Chemistry, University of Illinois at Urbana-Champaign
Molecular ions play an essential role in the chemistry that has formed the universe and
there is a need for high-precision laboratory spectra of ions that may be present in the interstellar
medium. In order to facilitate new astronomical discoveries and provide for a deeper
understanding of the chemical theory of molecular ions, it is necessary to improve the precision
to which spectra of such ions can be measured. However, forming ions in measurable quantities
in the laboratory has proved challenging due to low ion-to-neutral ratios. Typical discharge cells,
even when cryogenically cooled, are subject to high temperatures and pressures that result in
diluted and congested spectra which makes extracting chemical information difficult. Here, we
overcome this challenge by coupling an electric discharge to a continuous supersonic expansion
to form ions cooled to low temperatures (~30 K for ions that cool efficiently).
Cooling of ions formed by the discharge is achieved as high pressure gas leaving the
source expands adiabatically into a vacuum, creating an environment ideal for the longer-lived
existence of cooled ions. Noise-immune cavity-enhanced optical heterodyne molecular
spectroscopy (NICE-OHMS) is used to probe the expansion with mid-infrared radiation (3-5
µm) formed through difference frequency generation. To further improve the sensitivity of the
NICE-OHMS technique, the discharge is electrically modulated at 1 kHz and demodulated by a
lock-in amplifier before being recorded by a custom data acquisition program. Transitions of H3+
and HN2+ have been recorded with excellent signal-to-noise and rotational temperatures of 80120 K and 35-45 K, respectively. With verification that the source is producing rotationally cold
ions we plan to move on to study primary ions of astronomical significance, including H2CO+.
Presenting Author’s E-mail: talicsk2@illinois.edu
High Precision Spectroscopy of Molecular Ions Relevant to the Interstellar Medium
Charles R. Markus1,3, Adam Perry1, James Hodges1, G. Stephen Kocheril1, and Benjamin McCall1,2
cmarkus2@illinois.edu
1
Dept. of Chemistry, Univ. of Illinois at Urbana-Champaign, Urbana, IL 61801
Dept. of Astronomy, Univ. of Illinois at Urbana-Champaign, Urbana, IL 61801
3
cmarkus2@illinois.edu
2
In the vast cold regions between the stars, chemistry manages to thrive through interactions
between molecular ions and neutral species. These reactions are able to occur despite the low number
densities and temperatures of the interstellar medium (ISM) due to their low activation barriers. Therefore
molecular ions dominate the chemistry and dynamics of the ISM. Their observation allows for valuable
insight into the physical characteristics of these regions. Identifying molecular ions in the ISM is often
complicated by congested spectra requiring high precision laboratory data to make an assignment with
confidence. Recording laboratory spectra of molecular ions poses many challenges. They are often
produced in low number densities in laboratory discharges and their signals are dwarfed by neutral
species. To overcome this techniques which increase signal strength, reduce instrumental noise, and
discriminate between ions and neutrals are utilized. Our technique, described as noise immune cavity
enhanced molecular heterodyne velocity modulation spectroscopy (NICE-OHVMS), is able to
accomplish this. By putting our ion source within an optical cavity the effective path length is increased
by a factor of 100 allowing for weak absorption signals to be observed. Velocity modulation spectroscopy
is used to discriminate between ions and neutrals. To further improve our sensitivity heterodyne methods
are used. An electro-optic modulator phase modulates the light to produce sidebands, and detection occurs
at radio frequencies which reduces technical noise. The combination of these techniques allows for a wide
variety of molecular ions to be observed in the mid-IR. To gain high precision, we use a GPS referenced
frequency comb to calibrate our laser granting sub MHz precision of line centers. This technique has been
used to investigate HCO+, HeH+, H3+, CH5+, and OH+ which are all of astrochemical interest.
Analysis of Rotationally Resolved C3 using Updated Oscillator Strengths
Nicole C. Koeppen*
Department of Chemistry, University of Illinois, Urbana, IL 61801
Benjamin J. McCall
Departments of Chemistry and Astronomy, University of Illinois, Urbana, IL 61801
Observations of carbon chain molecules are useful in determining the temperature profiles of
diffuse interstellar clouds. In 2003, C3 was observed in ten different sightlines and the rotational
column densities and the temperature distributions were determined using the oscillator strengths
available at that time. The method for fitting these high signal-to-noise spectra involved separately
adjusting each rotational level population in order to obtain the best fit of the P, Q, and R branches.1
This past year, new oscillator strengths for the C3 rotational states were calculated by including
the effects from intensity borrowing to the nearby perturbing states.2 With these new oscillator
strengths, we have used the same method of individually fitting each J level population of the previous
ten C3 spectra to determine more accurate values for the rotational column densities, which are used to
calculate the temperatures of the clouds.
1
2
Adamkovics et al. Ap.J., 595, 235 (2003)
Schmidt et al. MNRAS, 441, 1134 (2014)
*presenting author's contact: nkoeppe2@illinois.edu
Spectrum of C3 observed in the sightline HD21483 from 2003,
shown with the updated fit (offset above) from independently
adjusting the rotational levels with the updated oscillator strengths.
Exploring Titan’s Atmospheric Chemistry Through Laboratory Simulations
Angela Weepie, Quentin Pavic, and Dr. Joshua Sebree
Department of Chemistry and Biochemistry, University of Northern Iowa
Titan, Saturn’s largest moon, is unique in that it is the only moon in our solar system with
a dense atmosphere. Titan has a temperature and pressure profile that allow for an active
hygrological system with gaseous, liquid, and solid phase methane and ethane taking the role that
water plays on Earth.2 While Titan is much colder, its atmospheric chemistry is comparable to
that of an early Earth.1 Understanding the chemical processes occurring in Titan’s atmosphere
today may shed light on chemical processes that occurred in Earth’s past.
Titan aerosol analogs were produced in a chamber in the laboratory of Dr. Joshua Sebree
(Figure 1) at the University of Northern Iowa. Aerosols were produced by mixing gases sourced
from tanks such as nitrogen, methane, and oxygen, and vapors sourced from headspace of
organics (1). The mixed gases are allowed to homogenize for a minimum of four hours in a
stainless steel mixing tank
(2) prior to use. Gas flow is
controlled by an Alicat
mass flow controller (3) to
ensure steady flow through
the chamber. As the gas
mix flows through the
reaction chamber, it is
exposed to UV light in the
115-400 nm wavelength
range (4). Aerosol particles
30 nm and larger are
collected on a glass fiber
filter in the collection
Figure'1'Titan&aerosol&chamber.&See&text&for&details
chamber (5).
Samples were further processed for UV-visible, mid-, and near-IR spectroscopy. The
spectra of laboratory produced aerosols from this study and previous work3 were compared with
in situ Titan data from the Cassini spacecraft Visual and Infrared Mapping Spectrometer (VIMS)
and Composite Infrared Spectrometer (CIRS).
References
1.
2.
3.
Cable, M.L., et al. Titan Tholins: Simulating Titan Organic Chemistry in the Cassini-Huygens Era.
Chemical Reviews 2011, 112 (3), 1882-1909
Czechowski, L.; Kossacki, K. Thermal Convection in the Porous Methane-Soaked Regolith of Titan:
Investigation of Stability Icarus 2009, 202, 599.
Sebree, J.A., et al. Titan aerosol analog absorption features produced from aromatics in the far infrared.
Icarus 2014, 236, 146-152.
Title:''The'measuring'of'cosmic'rays'during'a'high5altitude'balloon'flight'
'
Authors:'Michael'Madsen,'Bawa'Sadjifo,'Kyle'Spurgeon,'Elizabeth'Turcotte,'Angela'
Weepie,'Alex'Oberle'and'John'Ophus.'''
'
Contact'Information:'(Ophus)''McCollum'Science'Hall'14,'University'of'Northern'
Iowa,'Cedar'Falls,'Iowa.'50614'
'
During'an'upcoming'flight'of'the'Iowa'Near5Space'Project'Integrating'Research'and'
Education'(INSPIRE),'cosmic'rays'will'be'measured'with'an'SLR'camera'and'a'
magnetometer.''The'balloon'flight'will'be'expected'to'reach'up'to'100,000'feet'
during'its'approximate'35hour'flight.''The'capsule'will'be'constructed'by'the'
INSPIRE'fellows'and'launched'and'retrieved'in'mid'April'2015.''The'capsule'and'
materials'will'be'designed'to'withstand'temperatures'of'540'degrees'Celsius,'a'
pressure'approximately'1/100th'of'that'at'sea'level,'and'an'impact'of'approximately'
4.5'meters'per'second.''This'flight'will'also'be'coordinated'with'local'schools'in'
order'to'allow'middle'and'high'school'students'the'opportunity'to'experience'the'
launch'and'recovery'process.'
'
'
ADMIT: ALMA Data Mining Toolkit
Douglas N. Friedel1, Leslie W. Looney1, Lisa Xu2, Marc W. Pound3, Peter J. Teuben3,
Kevin P. Rauch3, Lee G. Mundy3, and Jeffrey S. Kern4
1
University of Illinois, Urbana, IL
National Center for Supercomputing Applications, Urbana, IL
3
University of Maryland, College Park, MD
4
National Radio Astronomy Observatory, Socorro, NM
2
ADMIT (ALMA Data Mining Toolkit) is a toolkit for the creation and analysis of new science
products from ALMA data. ADMIT is an ALMA Development Project written purely in Python.
While specifically targeted for ALMA science and production use after the ALMA pipeline, it is
designed to be generally applicable to radio-astronomical data. ADMIT quickly provides users
with a detailed overview of their science products: line identifications, line 'cutout' cubes,
moment maps, emission type analysis (e.g., feature detection), etc. Users can download the small
ADMIT pipeline product (< 20MB), analyze the results, then fine-tune and re-run the ADMIT
pipeline (or any part thereof) on their own machines and interactively inspect the results. ADMIT
will have both a GUI and command line interface available for this purpose. By analyzing
multiple data cubes simultaneously, data mining between many astronomical sources and line
transitions will be possible. Users will also be able to enhance the capabilities of ADMIT by
creating customized ADMIT tasks satisfying any special processing needs. Future
implementations of ADMIT may include EVLA and other instruments.
Impact of Laboratory Studies of the C + H3+ Reaction on Astrochemical Models
Shreyas Vissapragada, Daniel Wolf Savin
Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA; sv2421@columbia.edu
ABSTRACT
The chemistry of C + H3+ forming CH+, CH2+, and CH3+ has recently been investigated by
O’Connor et. al. (2014). These reactions are believed to be some of the initial gas-phase
astrochemical processes forming organic compounds in molecular clouds. Current astrochemical
models use the Langevin rate coefficient for CH+ formation and treat the CH2+ and CH3+ channels
as closed. O’Connor et. al. find that both the CH+ and the CH2+ channels are open. We have input
their rate coefficient results into the astrochemical model KIDA. Here, we report the impact of
these new data. This work was supported in part by NASA and the NSF.
REFERENCES
O’Connor et. al. (2014), arXiv:1408.4696v2
Talk Abstracts
The NASA Postdoctoral Program and other Early Career
opportunities at NASA!!
Joshua A. Sebree
University of Northern Iowa
Prior to starting at the University of Northern Iowa, I was a post-doc in the
NASA Postdoctoral Program (NPP) at Goddard Space Flight Center. Having only
learned of the program in the months before finishing my Ph.D. I was just able to
complete and submit my application for what was to be an exciting two years.
During this session I will discuss the NPP application process and what it was like
in the program. The floor will also be open for discussing additional programs at
NASA for graduate and undergraduate students.
CARMA 1 CM Line Survey of Orion-KL
Douglas N. Friedel1, Leslie W. Looney1, Anthony J. Remijan2, and Joanna Corby2
1
University of Illinois, Urbana, IL
National Radio Astronomy Observatory, Charlottesville, VA
2
We have conducted the first 1 cm (27-35 GHz) line survey of the Orion-KL region by an array.
With a primary beam of ~4.5 arcminutes, the survey looks at a region ~166,000 AU (0.56 pc)
across. The data have a resolution of ~6 arcseconds on the sky and 97.6 kHz(1.07-0.84 km/s) in
frequency. This region of frequency space is much less crowded than at 3mm or 1mm
frequencies and contains the fundamental transitions of several complex molecular species,
allowing us to probe the largest extent of the molecular emission. We will present the initial
results from several species including, dimethyl ether [(CH3)2O], ethyl cyanide [C2H5CN],
acetone [(CH3)2CO], SO, and SO2.
The complex 30 GHz continuum of the Orion-KL region. Many of the detected transitions
come from several individual regions within the complex.
Determining the Chemistry of Super-Earth Exoplanet Atmospheres
Eliza Kempton: kemptone@grinnell.edu || 1115 8th Avenue, Grinnell
College, Grinnell, 50112, USA
Abstract:
Extrasolar super-Earths (planets with size and mass intermediate between Earth
and Neptune) are now known to be highly abundant within our galaxy. These
objects are of particular interest to astronomers because planets in this mass and
size range are not present in our solar system. Super-Earths therefore make up a
fundamentally new class of planet for researchers to study. The population of
super-Earths is highly highly diverse in bulk composition – planets have been
discovered ranging from iron-rich, to water-rich, to hydrogen-rich. The first
observations of super-Earth atmospheres reveal planets that do not resemble any
solar system objects. I will discuss the challenges to determining the chemical
makeup of super-Earth atmospheres, and I will present constraints offered by the
initial observations of these planets.
Clouds in Super-Earth!Atmospheres - Equilibrium Chemistry Calculations!
Authors:
Rostom Mbarek: mbarekro@grinnell.edu || 1115 8th Avenue, Grinnell College, Grinnell, 50112,
USA || 1-515-809-5868
Eliza Kempton: Grinnell College
Abstract:
Recent observations of exoplanet atmospheres have revealed the presence of clouds in
planets of widely differing properties (e.g. mass, temperature, etc.). However, the composition
of these clouds remains unknown and is poorly constrained by theory. A theoretical description
of clouds in the atmospheres of low-mass exoplanets (super-Earths) is especially problematic,
since we expect a broad diversity of atmospheric composition for these planets in particular. We
provide a theoretical context for the formation of clouds in super-Earth atmospheres by
determining which condensates are likely to form, under the assumption of chemical equilibrium.
The composition of rocky planets is initially determined by the accretion of meteoritic material,
which builds up a solid planetary core. We model super-Earth atmospheres assuming that they
are then formed by degassing of volatile elements from the planet's interior. The atomic
abundances of the atmospheres are specified by the composition of volatiles released during the
degassing process. Given the atomic make-up of the atmosphere, we minimize the global Gibbs
free energy of over 500 gases, condensed liquids, and solids to obtain the molecular composition
of the atmosphere. Clouds should form along the temperature-pressure boundaries where the
condensed species appear in our calculation. Our results determine the plausible composition of
clouds that could form in degassed super-Earth atmospheres. We find clouds composed of
disparate compounds such as alimino-silicates, metal oxides, and salts, depending on the
temperature range and bulk atmospheric composition.
Low temperature HD + ortho-/para-H2 inelastic
scattering of astrophysical interest
Renat A. Sultanov1
Department of Information Systems and Integrated Science and
Engineering Laboratory Facility (ISELF) at St. Cloud State University,
St. Cloud, MN 56301-4498, USA
State-selected total cross sections and thermal rate coefficients are computed for the four-atomic HD + ortho-/para-H2 rotational energy transfer
collision at low temperatures (T) of astrophysical interest: 2K < T < 300K.
Together with the H2 + H2 collision, the four-atomic inelastic scattering
problem is of significant importance in the astrophysics of the early Universe,
in terms of the modeling of pre-galactic clouds and planetary atmospheres
[1]. A modified H2 -H2 potential energy surface (PES) from work [2] and
a pure quantum-mechanical dynamical approach is applied in the current
computation. A comparison between the new results for HD + ortho-/paraH2 and previous calculations [3] computed with the use of another older PES
[4] and with other results [5, 6], will be presented and discussed.
References
[1] A. Dalgarno and R. McCray, Ann. Rev. Astron. Astrophys. 10, 375
(1972).
[2] R.J. Hinde, J. Chem. Phys. 128, 154308 (2008).
[3] R. A. Sultanov and D. Guster, Chem. Phys. Lett. 436, 19 (2007);
R. A. Sultanov et al., Chem. Phys. Lett. 475, 175 (2009).
[4] A.I, Boothroyd, P.G. Martin, W.J. Keogh, and M.J. Peterson, J. Chem.
Phys. 116, 666 (2002).
[5] D. R. Flower, J. Phys. B 32, 1755 (1999).
[6] J. Schaefer, Astron. Astrophys. Suppl. Ser. 85, 1101 (1990).
1
E-mail: rasultanov@stcloudstate.edu
1
Exploring Pathways to Nitrogen Containing Heteroaromatics is Titan’s
Atmosphere: Spectroscopy of Cyanostyrene Isomers
Joseph A. Korn†, Stephanie N. Knezz‡, Robert J. McMahon‡, and Timothy S. Zwier†
† Purdue University, 560 Oval Drive, West Lafayette, IN 47907
‡ University of Wisconsin, 1101 University Avenue, Madison, WI 53706
Data from the 2005 Cassini-Huygens mission provided evidence that components of Titan’s
atmosphere are likely to include substituted benzenes that could play a role as intermediates
along pathways to form large polymeric tholins1. Models predict that small unsaturated
hydrocarbons and nitriles can undergo radical-driven reactions to form substituted aromatic
compounds.2 In this talk, we consider the ultraviolet spectroscopy of the three structural isomers
o-,m-, and p-cyanostyrene (C9H7N), which themselves are structural isomers of isoquinoline.
Excitation and emission spectra for the three cyanostyrenes will be presented under jet-cooled
conditions. The o-cyanostyrene was studied by resonant two-photon ionization, and prominent
bands were later studied by dispersed fluorescence. All three isomers were studied using laserinduced fluorescence, with prominent bands resolved via dispersed fluorescence. Spectra due to
the cis and trans isomers of m-cyanostyrene are resolved using ultraviolet depletion methods.
1.##Sebree,#J.#A.;#Kidwell,#N.#M.;#Selby,#T.#M.;#Amberger,#B.#K.;#McMahon,#R.#J.;#Zwier,#T.#S.,#
Photochemistry#of#Benzylallene:#RingEClosing#Reactions#to#Form#Naphthalene.#Journal(of(the(
American(Chemical(Society(2012,#134#(2),#1153E1163.#
2.##Landera,#A.;#Mebel,#A.#M.,#LowETemperature#Mechanisms#for#the#Formation#of#Substituted#
Azanaphthalenes#through#Consecutive#CN#and#C2H#Additions#to#Styrene#and#NE
Methylenebenzenamine:#A#Theoretical#Study.#Journal(of(the(American(Chemical(Society(2013,#135#
(19),#7251E7263.
Spectroscopic analysis of Titan Analog Aerosols
Angela Weepie, Quentin Pavic, and Dr. Joshua Sebree
Department of Chemistry and Biochemistry, University of Northern Iowa
%"Transmission"
Titan, Saturn’s largest moon, is unique in that it is the only moon in our solar system with
a dense atmosphere. Titan has a temperature and pressure profile that allow for an active
hygrological system with gaseous, liquid, and solid phase methane and ethane taking the role that
water plays on Earth.2 While Titan is much colder, its atmospheric chemistry is comparable to
that of an early Earth.1 Understanding the chemical processes occurring in Titan’s atmosphere
today may shed light on chemical processes that occurred in Earth’s past.
Titan aerosol analogs were produced in a chamber in the laboratory of Dr. Joshua Sebree
(Figure 1) at the University of Northern Iowa. Aerosols were produced by flowing Titan-specific
gases through a UV photochamber. Collected aerosols were further processed for UV-visible,
mid-, and near-IR spectroscopy.
%
Characteristic peaks in the near IR spectra
NIR"Zoom"
indicated the presence of polycyclic aromatic
63.2%
hydrocarbons3 (PAH’s). (Figure 1)
50%ppm%
The spectra of
100%ppm%
laboratory
produced
aerosols from this
study and previous 62.7%
1640% 1650% 1660% 1670%
work3 were compared
Wavelength"(nm)"
with in situ Titan data
Figure%1%
from
the
Cassini
spacecraft Visual and
Infrared Mapping Spectrometer (VIMS) and Composite Infrared
Spectrometer (CIRS). Figure 2 represents the spectra of several
Titan-analog aerosols compared with VIMS data from Titan’s
haze layer and at 950 km above the surface.
References
1. Cable, M.L., et al. Titan Tholins: Simulating Titan Organic
Chemistry in the Cassini-Huygens Era. Chemical Reviews 2011, 112 (3),
1882-1909
2. Czechowski, L.; Kossacki, K. Thermal Convection in the Porous
Methane-Soaked Regolith of Titan: Investigation of Stability Icarus 2009,
202, 599.
3. 2. Izawa, M.R.M., Applin, D.M., Norman, L., Cloutis, E.A.,
Reflectance spectroscopy (350-2500 nm) of solid-state polycyclic aromatic hydrocarbons (PAHs), Icarus
2014.
Sebree, J.A., et al. Titan aerosol analog absorption features produced from aromatics in the far infrared.
Icarus 2014, 236, 146-152.
Figure%2%
Sebree,&et&al&2014&
%
4.