Photochemical Reactions the Atmosphere

The Sun emits radiant energy over a wide range of wavelengths ( FIGURE 18.3). To understand the connection between the wavelength of radiation and its effect on 

Why doesn t the solar spectrum at sea level perfectly match the solar spectrum outside the atmosphere  

The rupture of a chemical bond resulting from absorption of a photon by a molecule is called photodissociation. No ions are formed when the bond between two atoms is cleaved by photodissociation. Instead, half the bonding electrons stay with one atom and half stay with the other atom. The result is two electrically neutral particles. 

One of the most important processes occurring above an altitude of about 120 km is photodissociation of the oxygen molecule  

The minimum energy required to cause this change is determined by the bond energy (or dissociation energy) of O2,495 kj/mol. 

---