L1 /
6
CH3041
OZONE - O3
UV absorption: The Chapman Mechanism
- formation and removal of O3 = 350 kT / d
- formation and removal of O3 = 350 kT / d
UV-C hn, l
< 240 nm DH, kJ/mol
1) O2 + hn ® 2O 498 – Ehn slow
1) O2 + hn ® 2O 498 – Ehn slow
3rd Body M (absorbs excess E)
2) O + O2 + M ® O3 -107 fast
2) O + O2 + M ® O3 -107 fast
t½ = 0.5h (30km)
UV-B hn, l < 320 nm
3) O3 + hn ® O2 + O 387 – Ehn fast
3) O3 + hn ® O2 + O 387 – Ehn fast
4) O + O3 ® 2O2
-392 slow
• With photon Es included all steps
are exothermic and so heat is
generated in the stratosphere.
are exothermic and so heat is
generated in the stratosphere.
