Searching for Life in Hot Spring Carbonate Systems: Investigating Raman Spectra of Carotenoid-Bearing Organic Carbonaceous Inclusions from Travertines of Italy.

Carotenoid pigments provide some of the most common exclusively biogenic markers on Earth, and these organic pigments may be present in extraterrestrial life. Raman spectroscopy can be used to identify carotenoids quickly and accurately through the inelastic scattering of laser light. In this study, we show that Raman spectra of organic matter found in hot spring bacterial assemblages exhibit "spectral overprinting" of the carotenoid spectrum by the carbon spectrum as the organic matter progressively breaks down.