Resonance Raman for molecular-specific studies in a complex material (Invited Paper)

Complex materials inherently have complex spectroscopic signatures, limiting the use of Raman spectroscopy. We show resonance Raman for 3 complex systems to identify the presence of a moiety, and use its resonantly enhanced Raman spectra to identify molecular modifications. The large enhancement makes the Raman signal dominated by the resonant molecules. We show that heme still attached to globin remnants still exists in (complex) soft tissue extracted from B. canadensis and T. rex, but the heme outer ring has been damaged. Further, evidence of goethite on the heme still attached to the globin remnants suggests preservation modes. Modern analogs show similar trends. We separately show that methylated cytosine can be distinguished from un-methylated cytosine using resonance Raman with state-of-the-art sensitivity. Finally, phonon-allowed resonance excitation in PARes-Raman on benzene produces Raman signal gain of 3500x with an excitation wavelength change of 0.01 nm. This signal gain and narrow linewidth represents a further step to separately analyze chemical moieties in complex materials w/o sacrificing signal level but still providing Raman spectral vibration information.