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Fig. 10 | Heritage Science

Fig. 10

From: Artificial weathering of rock types bearing petroglyphs from Murujuga, Western Australia

Fig. 10

Representative Raman spectra from the same location on a gabbro sample surface, measured before (red) and after (blue) 3 months of artificial weathering with a 532.09 nm laser. Beside the characteristic quartz band near 464 cm−1, multiple bands occur in the frequency range between 900 and 1800 cm−1 which indicate the occurrence of complex organic material (all bands with frequency labels). These bands do not occur in the spectrum taken after artificial weathering (blue spectrum), where only the D- and G-band of carbonaceous matter are visible. These carbonaceous bands occur also in the red spectrum, but here are overlapped by organic bands. The sharp signal at 1707.06 cm−1 is a neon line that was used to correct for any spectrometer drift during long-time measurements

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