91Ó°ÊÓ

Absorption spectrum indicates dark lines presence in spectrum when radiation transmitted through a substance indicating absorption at specific wavelengths of electromagnetic radiation.

The given chart has values for absorption of particular wavelength radiation by specific functional group.

Functional group absorption band

Here three functional groups are present namely alkene, nitrile group and ketone group. Red atom indicated here is oxygen and blue atom is nitrogen according to book.

Here three absorption bands will be seen:

• Nitrile group absorption band is seen at 2210-2260\(c{m^{ - 1}}\).
• Ketone group absorption band is at 1690\(c{m^{ - 1}}\). This lower value is due to the presence of the ketone group next to the double bond.
• Alkene group \( - C = C - \) band at 1640-1680\(c{m^{ - 1}}\).