Figure displays the infrared absorption spectra of melamine, TCNE, and doped melamine crystals. The spectrum of melamine exhibits modes of the triazine ring at 814, 1026, 1436 and 1551 cm -1 , the bending mode of -NH 2 at 1652 cm -1 , and the stretching modes of -NH 2 at 3130, 3333, 3419 and 3469 cm-1. .