Fig. 3. XPS and PXRD data for PTI·LiBr and IF-PTI. Elemental compositions are given in atomic percent. The C content from PTI is reported after removal of the contribution from adventitious signals. (a) XPS survey scan of PTI·LiBr showing significant C, N and Br content, along with the presence of a small percentage of O impurities, presumably due to surface contamination. (b) XPS survey scan of IF-PTI showing similar C, N and O content, but with the Br signal notably absent. (c) PXRD pattern of IF-PTI overlaid with calculated pattern based on the PTI·LiBr structure (assuming AA′ stacking with a smaller interlayer spacing), demonstrating the significantly smaller interlayer spacing. (d) TEM image of hexagonal crystallites of IF-PTI with a Fourier transformed pattern showing the characteristic in-plane distances of the 100 and 110 reflections for PTI (for IF-PTI it was found a = b = 8.51 Å, c = 6.58 Å).