Most spectra using electromagnetic radiation are presented with wavelength as the X-axis. Originally, IR spectra were presented in units of micrometers..IR Spectra: Tricks for. Identifying the 5 Zones. It 's easier than you think! . Introduction: The light our eyes see is a small part of a broad spectrum of .By Arthur Winter. IR infrared spectroscopy is useful in organic chemistry because it enables you to identify different functional groups. This is because each . - However, we 've seen that IR spectroscopy can a great technique for identifying certain functional groups in an unknown molecule - especially .