PHOTONS IN CHEMISTRY OUT PHOTONS IN CHEMISTRY OUT

PHOTONS IN CHEMISTRY OUT

PHOTONS IN CHEMISTRY OUT WHY BOTHER?

1. Remote action

1. Remote action

Light has: • Intensity • Color (wavelength) • Polarization

E=hν

Light has: • Intensity • Color (wavelength) = ENERGY • Polarization

1. Remote action 2. Energetics

(wavelength) x (frequency) = speed [m/s] λν = c [108 m/s]

E=hν

~ 450 -750 nm Take 500 nm

Boltzman

Boltzman T [o. K] 300 400 1000 2, 000 5, 000 6, 400 10, 000 20, 000 50, 000 n 2/n 1 3 x 10 -42 7 x 10 -32 3. 4 x 10 -13 6 x 10 -7 3 x 10 -3 1% 5. 7 % 24 % 56 %

Boltzman T [o. K] 300 400 1000 2, 000 5, 000 6, 400 10, 000 20, 000 50, 000 n 2/n 1 3 x 10 -42 7 x 10 -32 3. 4 x 10 -13 6 x 10 -7 3 x 10 -3 1% 5. 7 % 24 % 56 %

Boltzman T [o. K] 300 400 1000 2, 000 5, 000 6, 400 10, 000 20, 000 50, 000 n 2/n 1 3 x 10 -42 7 x 10 -32 3. 4 x 10 -13 6 x 10 -7 3 x 10 -3 1% 5. 7 % 24 % 56 %

Boltzman T [o. K] 300 400 1000 2, 000 5, 000 6, 400 10, 000 20, 000 50, 000 n 2/n 1 3 x 10 -42 7 x 10 -32 3. 4 x 10 -13 6 x 10 -7 3 x 10 -3 1% 5. 7 % 24 % 56 %

Boltzman T [o. K] 300 400 1000 2, 000 5, 000 6, 400 10, 000 20, 000 50, 000 n 2/n 1 3 x 10 -42 7 x 10 -32 3. 4 x 10 -13 6 x 10 -7 3 x 10 -3 1% 5. 7 % 24 % 56 %

Grotthuss-Draper law: Only the light absorbed in a molecule can produce photochemical Change in the molecule (1871 and 1841) Stark - Einstein: If a species absorbs radiation, then one particle is excited for each quantum of radiation absorbed

Primary Φ ≤ 1 Sum of all primary Φ’s =1 QUANTUM YIELD: Φ = The number of molecules of reactant consumed for each quantum of radiation absorbed Stark - Einstein: If a species absorbs radiation, then one particle is excited for each quantum of radiation absorbed