3.5. FTIR-ATR –LIBS Heterospectral 2DCOS
In addition, 2D heterospectral correlation maps were used to examine the covariation between bands in FTIR-ATR and LIBS spectra. A molecular and atomic 2D heterospectral correlation map was used, as this could reflect the functional compounds at positive/negative peaks derived from the same origin (Yu et al., 2012).
In the synchronous map (Fig. 8), the negative cross-peaks were located at 995 (Si–O in clay mineral) and 4000–2940 cm-1(O–H in clay mineral) in the FTIR-ATR spectra and at 517 (Mg I), 558 (Ca I), 588 (Na I), and 766 (K I) nm in the LIBS spectra.