“…The peaks at 1634, 1550, and 1470 cm -1 indicate the presence of pyrrole, whereas the peaks at 1385 and 1308 cm -1 arise from the N-C vibration and the deformation of pyrrole. The peaks in the 750~930 cm -1 range and at 1043 cm -1 originate from C-H absorption [23,24]. Further, the FTIR peak at 690 cm -1 is attributed to C-S stretching, as reported previously in the literature [23].…”