2. Photochemical kinetics

4. Intensity

5. Transmittance Absorbance

6. Transmittance Absorbance Beer’s Law

7. dP(x)/dx = -κ P(x)  P(x) = exp(-κ x)

8. Beer’s law

9. Molar extinction Coefficient ~250 L.mol -1 cm -1 Cross section ~10 -18 cm 2

11. ε = 313 M -1 cm -1 b = 2 cm T = 3.16% = 0.0316 A = -logT = 1.50 c = 1.5/(313 M -1 ) (2 cm -1 ) = 0.0024 M

12. NB 1: Beer fails when photochemistry happens NB 2: The photophysics Is hidden in σ (So we haven’t done much yet)

14. Absorption of a mixture

15. Isosbestic point

16. Photochemical kinetics STEADY STATE HYPOTESIS

17. Ozone production Photochemical kinetics λ ≤ 240 nm λ ≤ 280 nm

18. λ ≥ 280 nm

20. 1.Steady state hypothesis: d[O]/dt = 0 2.Solve for [O] 3.Plug into disappearance rate of [O 3 ]