Infrared Action Spectroscopy of Biomolecules for Planetary Science Applications
Year: 2026
Type: dissertation
Abstract: The search for extraterrestrial life in our solar system requires the development of novel in situ instrumentation capable of detecting biosignatures in planetary environments and biological samples. This thesis applies infrared (IR) action spectroscopy of mass-selected ions toward this goal, demonstrating the ability to unambiguously characterize planetary-relevant biomolecules in liquid samples for various test cases. Action spectra are generated by plotting a photodissociation yield for biomolecular ions of interest as a function of IR frequency. In Chapter II, I describe the setup and operating procedures of an action spectrometer that uses a quantum cascade laser (QCL) (1000-1600 cm-1) and a Cr:ZnSe/S laser (3300-3800 cm-1), as well as describe general data processing procedures. In Chapter III, I describe the initial demonstration of the relatively compact, QCL-based action spectrometer, highlighting its ability to record action spectra of room temperature, water-tagged amino acids and discern amino acid isomers in mixtures. In Chapter IV, I record the action spectra of planetary-relevant, water-tagged amino acid isomers using the QCL-based instrument. I distinguish between the isomers using a combination of spectrum matching and machine learning methods. In Chapter V, I use the Cr:ZnSe/S laser-based action spectrometer to record multiplexed action spectra of protonated amino acids and nucleosides from bacterial samples, with some trials at lower laser output power than contemporary methods. In Chapter VI, I show progress towards differentiating amino acid enantiomers by recording action spectra of non-covalent chiral tag-amino acid complexes using the Cr:ZnSe/S laser-based action spectrometer. In Chapter VII, I recorded action spectra of additional biomolecules, including small molecules, carbohydrates, and a pigment. Overall, this thesis will aid future development of in situ instruments for astrobiology missions and general analytical applications.
Source: Caltech Library
DOI: 10.7907/jxjd-3b72
Author: Nguyen, Tyler Minh-Hung
Institution: California Institute of Technology
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: G126738435, G3648211085
OpenAlex ID: W7162118807
Cites:
Cited by:
Related to: