PHOTONS INCHEMISTRY OUT

PHOTONS INCHEMISTRY OUT

WHY BOTHER?

1.Remote action

1.Remote action

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

E = h ν

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

1.Remote action

2.Energetics

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

λν = c [108 m/s]

E = h ν

E hc

hcE

34 8

9

16

6.6 10 3 10

10

2 10

Js m sE

nm m

nmJ

1234 eVnm

191 1.6 10

119627kJ molnm

1000

N

~ 450-750 nm

Take 500 nm

12342.5

500hE eV

194 10 J

240kJ mol

2

1

E RTne

n

3

4

240 10 8.3

2.87 10

T

T

e

e

Boltzman

42.87 102

1

Tne

n Boltzman

T [oK] n2/n1

300 3 x 10-42

400 7 x 10-32

1000 3.4 x 10-13

2,000 6 x 10-7

5,000 3 x 10-3

6,400 1 %

10,000 5.7 %

20,000 24 %

50,000 56 %

42.87 102

1

Tne

n Boltzman

T [oK] n2/n1

300 3 x 10-42

400 7 x 10-32

1000 3.4 x 10-13

2,000 6 x 10-7

5,000 3 x 10-3

6,400 1 %

10,000 5.7 %

20,000 24 %

50,000 56 %

42.87 102

1

Tne

n Boltzman

T [oK] n2/n1

300 3 x 10-42

400 7 x 10-32

1000 3.4 x 10-13

2,000 6 x 10-7

5,000 3 x 10-3

6,400 1 %

10,000 5.7 %

20,000 24 %

50,000 56 %

42.87 102

1

Tne

n Boltzman

T [oK] n2/n1

300 3 x 10-42

400 7 x 10-32

1000 3.4 x 10-13

2,000 6 x 10-7

5,000 3 x 10-3

6,400 1 %

10,000 5.7 %

20,000 24 %

50,000 56 %

42.87 102

1

Tne

n Boltzman

T [oK] n2/n1

300 3 x 10-42

400 7 x 10-32

1000 3.4 x 10-13

2,000 6 x 10-7

5,000 3 x 10-3

6,400 1 %

10,000 5.7 %

20,000 24 %

50,000 56 %

Grotthuss-Draper law:

Only the light absorbed in a moleculecan 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

Stark - Einstein:

If a species absorbs radiation, then one particle is excited for each quantum of radiation absorbed

QUANTUM YIELD:

Φ = The number of molecules of reactant consumed for each quantum of radiation absorbed

Primary Φ ≤ 1Sum of all primary Φ’s =1