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Photochemical kinetics

Photochemical kinetics. Intensity. Transmittance. Absorbance. Why LOG?. Transmittance. Absorbance. Beer’s Law. dP( x )/dx = - κ P( x ).  P( x ) = exp(- κ x ). Beer’s law. Cross section ~10 -18 cm 2. Molar extinction Coefficient ~250 L.mol -1 cm -1. ε = 313 M -1 cm -1

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Photochemical kinetics

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  1. Photochemical kinetics

  2. Intensity

  3. Transmittance Absorbance Why LOG?

  4. Transmittance Absorbance Beer’s Law

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

  6. Beer’s law

  7. Cross section ~10-18 cm2 Molar extinction Coefficient ~250 L.mol-1cm-1

  8. 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

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

  10. Absorption of a mixture

  11. Isosbestic point

  12. Photochemical kinetics STEADY STATE HYPOTESIS

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

  14. λ≥ 280 nm

  15. Steady state hypothesis: d[O]/dt = 0 • Solve for [O] • Plug into disappearance rate of [O3]

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