A5023181160- Astro and Planetary Science
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Atmospheric chemistry and aerosols
- Astrophysics and Star Formation Studies
- Advanced Chemical Physics Studies
- Molecular Spectroscopy and Structure
- Space Exploration and Technology
- Isotope Analysis in Ecology
- Photochemistry and Electron Transfer Studies
- Spacecraft and Cryogenic Technologies
- Spectroscopy and Laser Applications
- Atmospheric and Environmental Gas Dynamics
- Gas Sensing Nanomaterials and Sensors
- Geology and Paleoclimatology Research
- Coffee research and impacts
- Various Chemistry Research Topics
- Mass Spectrometry Techniques and Applications
- Stellar, planetary, and galactic studies
- Karst Systems and Hydrogeology
- Catalytic Processes in Materials Science
- Radioactive contamination and transfer
- Origins and Evolution of Life
- Analytical Chemistry and Chromatography
- Educational Environments and Student Outcomes
University of Northern Iowa
2014-2024
Goddard Space Flight Center
2011-2015
Purdue University West Lafayette
2010-2011
Florida International University
2010
University of Regensburg
2007
Abstract Over 4 billion years ago, Earth is thought to have been a hazy world akin Saturn’s moon Titan. The organic hazes in the atmosphere at this time could contained vast inventory of life’s building blocks and thus may seeded warm little ponds for life. In work, we produce lab atmospheres with high (5%) low (0.5%) CH abundances analyze solid particles nucleobases, amino acids, few other organics using GC/MS/MS obtain their concentrations. We also heated (200°C) samples from methane haze...
Benzene has been detected in Titan's atmosphere by Cassini instruments, with concentrations ranging from sub-ppb the stratosphere to ppm ionosphere. Sustained levels of benzene haze formation region could signify that it is an important reactant organic aerosol. To date, there have not laboratory investigations assess influence on aerosol properties. We report a study chemical composition formed C6H6/CH4/N2 via far ultraviolet irradiation (120–200 nm). The compositional results are compared...
Abstract Impacts are critical to producing the aqueous environments necessary stimulate prebiotic chemistry on Titan’s surface. Furthermore, organic hazes resting surface a likely feedstock of biomolecules. In this work, we conduct impact experiments laboratory-produced haze particles and haze/sand mixtures analyze these samples for life’s building blocks. Samples unshocked sand also analyzed determine change in biomolecule concentrations distributions from shocking. Across all samples,...
Vibronic spectra of doublet-doublet transitions 1-hydronaphthyl (1HN), 2-hydronaphthyl (2HN), and 1,2,3-trihydronaphthyl (THN, tetralyl) radicals have been recorded under jet-cooled conditions. Transitions due to the two C(10)H(9) isomers were identified assigned based on choice radical precursor, visible-visible hole-burning spectroscopy, comparison observed vibronic with calculation, photoionization efficiency scans. The latter provided accurate ionization potentials for three free...
Abstract CO is an important component in many atmospheres, including Titan, Triton, and Pluto, has also been detected the atmosphere of a number exoplanets. Numerous experimental simulations have carried out laboratory to understand chemistry but very few included initial gas mixtures. The effect on occurring these atmospheres still poorly understood. We investigated both solid phase series planetary simulation experiments using mixtures CO, , with range mixing ratios from 0.05% 5% at low...
Abstract The formation and identification of prebiotic compounds in the organically rich atmospheres Titan Pluto are great interest due to potential implications such discoveries may have on theories origins life early Earth. In past work, hindrances detecting molecules lab-generated aerosol analogs been large number products formed, often compounded by limited sample amounts. this we detail a GC/MS/MS protocol that is highly selective (>30 simultaneously detectable compounds) sensitive...
Mass-selective two-color resonant two-photon ionization (2C-R2PI) spectra of two resonance stabilized radicals (RSRs), 1-phenylallyl and benzylallenyl radicals, have been recorded under jet-cooled conditions. These while sharing the same radical conjugation, unique properties. The D0–D1 origin is at 19208 cm−1, with extensive vibronic structure extending over 2000 cm−1 above D1 origin. Much this assigned based on comparison DFT TDDFT calculations. Two-color photoionization efficiency scans...
Laboratory investigations of the isomer-specific spectroscopy several C10Hn isomers with n = 8–12 are described, focusing on structures relevance to formation or subsequent reaction naphthalene. The photochemical models Titan's atmosphere have now progressed point that further development large-molecule end model must recognize and explicitly incorporate unique spectroscopy, photochemistry, reactivity structural isomers. Mass-resolved, resonant two-photon ionization (R2PI) was used record...
Abstract Very little experimental work has been done to explore the properties of photochemical hazes formed in atmospheres with very different compositions or temperatures than those outer solar system early Earth. With extrasolar planet discoveries now numbering thousands, this untapped phase space merits exploration. This study presents measured chemical haze particles produced laboratory analogs exoplanet atmospheres. We used high-resolution mass spectrometry measure components solid...
Van der Waals clusters of phthalocyanine with 1-4 argon atoms formed inside superfluid helium nanodroplets have been investigated by recording fluorescence excitation spectra as well emission spectra. The feature a multitude sharp lines when recorded in droplets contrast to the respective measured seeded supersonic beam (Cho et al. Chem. Phys. Lett. 2000, 326, 65). pickup technique used for doping and into allows nondestructive analysis cluster sizes. Alternation sequence gives information...
Abstract In Titan’s nitrogen-methane atmosphere, photochemistry leads to the production of complex organic particles, forming thick haze layers. Laboratory-produced aerosol analogs, or “tholins,” are produced in a number laboratories; however, most previous studies have investigated analogs by only one laboratory rather than systematic, comparative analysis. this study, we performed study an important material property, surface energy, seven tholin samples three independent laboratories...
Triton is the largest moon of Neptune system and possesses a thin nitrogen atmosphere with trace amounts carbon monoxide methane, making it similar composition to that dwarf planet Pluto. Like Pluto Saturn's Titan, has haze layer thought be composed organics formed through photochemistry. Here, we perform atmospheric chamber experiments 0.5% 0.2% methane in molecular at 90 K 1 mbar generate analogues. We then characterize physical chemical properties these particles. measure their production...
Conformer-specific, vibrationally resolved electronic spectroscopy of benzylallene (4-phenyl-1,2-butadiene) is presented along with a detailed analysis the products formed via its ultraviolet photoexcitation. Benzylallene minor product recombination benzyl and propargyl radicals. The mass-selective resonant two-photon ionization spectrum was recorded under jet-cooled conditions, S0–S1 origin at 37 483 cm–1. UV–UV holeburning used to show that only one conformer present in expansion....
Laser induced fluorescence (LIF) excitation scans and dispersed (DFL) spectra have been recorded for two four-carbon α,ω-diphenyl systems, diphenyldiacetylene (DPDA, φ-C≡C-C≡C-φ) trans-diphenylvinylacetylene (DPVA, φ-CH≡CH-C≡C-φ) as isolated molecules cooled in a supersonic expansion. While these similar conjugation length, they exhibit strikingly different vibronic spectroscopy photophysics. The near-UV LIF spectrum of has its electronic origin at 32,158 cm(-1), strong progression the C≡C...
Chemistry in Titan's N2–CH4 atmosphere produces complex organic aerosols. The chemical processes and the resulting compounds are still far from understood, although extensive observations, laboratory, theoretical simulations have greatly improved physical constraints on atmosphere. Here, we conduct a series of Titan simulation experiments with gas mixtures investigate effect initial CH4 ratio, pressure, flow rate production rates composition solid products at relevant temperature (100 K) for...
Over 4 billion years ago, Earth is thought to have been a hazy world akin Saturn's moon Titan. The organic hazes in the atmosphere at this time could contain vast inventory of life's building blocks, and thus may seeded warm little ponds for life. In work, we produce lab atmospheres with high (5%) low (0.5%) CH4 abundances analyze solid particles nucleobases, amino acids, few other organics using GC/MS/MS obtain their concentrations. We also heated (200 $^{\circ}$C) samples from methane haze...
Impacts are critical to producing the aqueous environments necessary stimulate prebiotic chemistry on Titan's surface. Furthermore, organic hazes resting surface a likely feedstock of biomolecules. In this work, we conduct impact experiments laboratory-produced haze particles and haze/sand mixtures analyze these samples for life's building blocks. Samples unshocked sand also analyzed determine change in biomolecule concentrations distributions from shocking. Across all samples, detect seven...