Calcite Raman spectra

Table 6.2 Ratios of different intensities in calcite Raman spectra obtained with different excitatirai wavelengths, (nm)...

Figure 8.18. Effect of HNF angle on Raman spectrum of calcite. Increasing the angle shifts the rejection band to lower Raman shift but also decreases the optical density at the laser wavelength. (Adapted from Reference 11. with permission.)...

Figure 1-5 shows a section of chasmolithic feldspar from Lake Hoare, Antarctica, in which two zones of bacterial colonisation can be clearly seen, from which the Raman spectrum of calcite can be clearly identified closely associated with the colonisation zones signatures of quartz and feldspar can also be seen in the spectrum. 

Figure 1-5. Chasmolith in feldspar, Lake Hoare, Antarctica with the Raman spectrum of calcite, quartz and feldspar from the cyanobacterial colonisation zone (see color plate section)...

Figure 1-17. Sabkha surface crust with gypsum and halite crystals, Rhub-al-Khalil, Arabian desert cyanobacterial colonisation at interface with subsurface dolomitized calcite. The Raman spectrum shows the presence of scytonemin and carotene in the biological zone...

Fig. 6.26 (a-d) Short-lived orange luminescence spectrum (X x = 532 nm) of radiation-induced center in calcite and its decay as a function of delay time (a). Gated Raman spectra with excitation at 532 nm and gate widths of 10 ns (b) and 0.5 ns (d). CW Raman spectrum with excitation at 785 nm (c)... 

The IR spectrum obtained from a very small amount of powder detached from the piece is shown in Fig. 10. The spectrum consists mainly of gypsum substrate and no evidence for pigments is seen because our FTIR spectrometer range is at the limit of the hematite band positions. The same fitting analysis allows the identification of a small contribution of calcite, which cannot be seen in the Raman spectrum. 

Figure 15 FT-Raman spectrum of the yellow pigment found in the S Baudelio church. The mixture comprises litharge, yellow ochre, quartz, calcite. Broad bands from lime wash at 790 cm are also seen.

---