The two triazine ring modes in the FT-IR spectra of PTI-LiBr are observed at 809 and 666 cm -1 . In comparison, the ring modes of PTI-IF are observed at 802 and 642 cm -1 . We attribute the higher energy ring-modes of PTI-LiBr to structural strain that is induced by the intercalated ions. We present the observed and calculated energies of the modes and a visual representation of the deformation vectors in an overview figure and table (Figure ) to guide future interpretation of vibrational spectra of triazine-based carbon nitrides. Generally, the inhomogenous distribution of ions throughout the PTI-LiBr structure causes a significant broadening of the vibrational bands in all spectroscopic methods. Removal of the ions from the structure leads to a more homogenous chemical environment throughout PTI-IF and, hence, to narrower bands. We applied diffuse reflectance spectroscopy, valence band electron energy loss spectroscopy (VB-EELS) (Figure ), DFT (Figure ), and UPS (Figure ) to determine the size (eV), the nature (direct or indirect), and the energetic position of the bandgap of PTI-type materials.