Photoionization processes (e. g., N2 + hν → N2+ + e–) remove UV light with λ <150 nm. Which photoreaction is the principal absorber of UV light in the 150-200 nm range in the upper atmosphere? N2 + hν → 2N O3 + hν → O2 + O O2 + hν → 2O NO + O2 + hν → NO3 N2 + O2 + hν → 2NO