Practice question

Electromagnetic spectrum couples with distinct molecular energy levels. Microwave photons induce rotational transitions, infrared photons drive vibrational stretching and bending, X-rays eject inner core electrons causing ionization. Outer valence electrons from bonding π, nonbonding n to antibonding π*, σ* orbitals require photon energies approximately two to seven electron volts corresponding to wavelength range 200-800 nm, spanning ultraviolet and visible region. Consequently colored biomolecules, conjugated cofactors such as heme, carotenoids, chlorophyll, flavins and aromatic amino acids and nucleic acid bases absorb in UV-Visible region, enabling spectrophotometric analysis of biochemical reactions and purity.