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Laser Spectroscopy of Hydrocarbons for Applications in Atmospheric and Space Science


Ober, Douglas Clifford (2023) Laser Spectroscopy of Hydrocarbons for Applications in Atmospheric and Space Science. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/x42v-ry39.


This thesis describes applications of spectroscopy and mass spectrometry towards applications of in situ sensing, chemical kinetics, and photodissociation processes of hydrocarbon species. Both mass spectrometry and cavity ring-down spectroscopy are used in this work. Irradiation of protonated coronene was used to study photodissociation process of polycyclic aromatic hydrocarbons (PAHs), with the power, irradiation time, and fragmentation studied to elucidate a photofragmentation mechanism. Biomolecules were ionized via Direct Analysis in Real Time (DART) to explore the feasibility and sensitivity of the ionization technique for different chemical species for in situ measurement in simulated extraterrestrial conditions. Photofragmentation and DART ionization were combined to quantify mixtures of isobaric PAHs, providing a tunable and complimentary technique for in situ analysis of mixtures. Finally, frequency-stabilized cavity ring-down spectroscopy was used to analyze precise ¹³CH₄, CH₃D, and CH₂D₂ to CH₄ isotologue ratios using optically-switched dual-wavelengths, allowing for sensitive measurement of the kinetic isotope effect of methane oxidation with O(¹D).

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Coronene, Direction Analysis in Real Time, Isomer Quantification, Kinetic Isotope Effect, Methane KIE
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Okumura, Mitchio
Thesis Committee:
  • Blake, Geoffrey A. (chair)
  • Okumura, Mitchio
  • Beauchamp, Jesse L.
  • Hodyss, Robert P.
  • Cushing, Scott K.
Defense Date:1 June 2023
Non-Caltech Author Email:douglascober (AT)
Funding AgencyGrant Number
NASA Solar Systems Workings Program80NSSC18K0263
NASA President's and Director's Research Development Fund80NM0018D0004
NASA President's and Director's Research Development Fund80NM0018D0004W
Record Number:CaltechTHESIS:05312023-235401985
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 2 Comb Work
Ober, Douglas Clifford0009-0005-2257-5029
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15249
Deposited By: Douglas Ober
Deposited On:06 Jun 2023 15:20
Last Modified:13 Jun 2023 18:43

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