Infrared Action Spectroscopy for Planetary Science Applications
In the search for extraterrestrial life in our solar system, it is critical to unambiguously identify and quantify organic compounds. Infrared (IR) action spectroscopy enhances current analytical methods by identifying molecules by both mass and IR spectra at parts-per-billion concentrations.
In collaboration with NASA JPL, we are developing an infrared action spectrometer consisting of a quantum cascade laser coupled to a quadrupole ion trap mass spectrometer.
When a given frequency of light is absorbed by a water-tagged ion, the water tag will dissociate from the ion (as seen in mass spectra). The fraction of dissociated ions as a function of IR frequency gives an IR action spectrum. Current molecular targets include amino acids (canonical and non-canonical) and their isomers, lipids, and polycyclic aromatic hydrocarbons.
Top: Infrared action mechanism and corresponding mass spectrum. Bottom: Experimental spectra of alanine isomers compared to density functional theory and determination of relative abundances in a mixture.