In Situ Detection of Organics in Ice via Mid-Wave IR Laser Stimulated Photothermal Effect

In Situ Detection of Organics in Ice via Mid-Wave IR Laser Stimulated Photothermal Effect

 

Christopher Duffey, Julie Brisset, Christopher Bennett, Jakob Haynes, Myles Hoskinson

Florida Space Institute, University of Central Florida, Orlando, FL

 

In-situ spectroscopic analysis is crucial for characterizing organic compounds within the ices of icy ocean worlds and comets. These non-destructive techniques enable the direct identification and quantification of molecular species within their native environments, avoiding potential contamination or alteration associated with sample return missions. By analyzing the spectral signatures of the ice matrix and embedded organics, we can gain critical insights into the composition, distribution, and potential prebiotic significance of these molecules, directly informing our understanding of the astrobiological potential of these celestial bodies.

Our research is the application of an Optical Photo Thermal Infrared (O-PTIR) Spectroscopy for the identification of minerals and organic molecules not only in meteoritic materials but also in ice and mineral ice mixtures.  We are currently working on maturing this technology and developing a reduced size, weight, and power prototype.  We are also integrating Raman spectroscopy as well as capabilities to identify organic chirality.

O-PTIR is a vibrational spectroscopy technique that uses a tunable IR laser to stimulate the photothermal effect in a sample and a 532 nm probe laser to measure the magnitude of the photothermal effect, the resulting spectrum provides mid-IR absorption at high spatial and spectral resolution.  The O-PTIR system provides high speed, analysis of material without any mechanical, chemical alteration/preparation, or damage to the sample. The surface of the sample is simultaneously optically imaged at sub-micron resolution and material absorption spectra can be correlated with the visible features of the sample.

We present the methods used to create the icy organic mixes and keep them cold during the spectroscopic analysis – as well as how we vary the organic constituents and concentrations relative to the icy matrix.

We show a variety of positive detection spectra of individual amino acids in water ice, as mixtures of multiple amino acid combinations and with both crystalline and amorphous ice matrixes. Hyperspectral maps of the detected organics and their spatial relationships and distributions to other species in the sample are also presented.  Figure 1 shows example data for an organic ice sample.