Optical Photothermal Infrared Spectroscopy (O-PTIR) – biorxiv.org
Identifying the organic material preserved within fossils is difficult. Established vibrational spectroscopy techniques, such as micro-FTIR (Fourier transform infrared spectroscopy), are widely used to investigate the molecular composition of organic fossils.
However, even if successfully adapted to study objects with diameters of tens of micrometers, they still suffer from limitations, especially regarding resolution and sample preparation requirements. Optical photothermal infrared spectroscopy (O-PTIR), a recently developed technology, overcomes the challenges of benchtop FTIR spectroscopy.
By combining an IR excitation laser with a 532 nm green probe laser, this technique enables molecular characterization with high spectral resolution (~2 cm-1) and very fine spatial resolution (~500 nanometers). Masu. Additionally, issues related to sample thickness, surface roughness, and particle shape/size are reduced when compared to FTIR or atomic force microscopy-based nanoIR techniques.
Here we show that O-PTIR can be used to easily and successfully map the molecular composition of small organic fossils preserved in a silica matrix (chert) in petrological thin sections. Our study shows that O-PTIR resolves spatial heterogeneity in the preserved molecular composition of organic fossils (spores and plants) at the submicron scale, and that such heterogeneity was associated with early Devonian We found that it occurs in the cuticle of plants, suggesting a structural organization. Comparable to modern plants.
These results on 400 million year old fossils validate O-PTIR as a powerful and highly promising new tool for nanoanalytical paleontology.
Optical photothermal infrared spectroscopy (O-PTIR): a promising new tool for benchtop analytical paleontology at the submicron scale
Corantin C. Rolon, Ferenc Borondics
doi: https://doi.org/10.1101/2024.02.08.579492
astrobiology
