FIG. 5.

Sample 5 (785 nm excitation). (A) Calcite; (B) anatase; (C) quartz with broad features between 1200 and 1800 cm⁻¹ tentatively suggested as signs of the presence of the highly condensed network of polycyclic aromatic hydrocarbons; (D) hematite (below 700 cm⁻¹) with broad features similar to those in the spectrum above.