PHOTONS IN CHEMISTRY OUT
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PHOTONS IN CHEMISTRY OUT
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PHOTONS IN CHEMISTRY OUT. PHOTONS IN CHEMISTRY OUT. WHY BOTHER?. Remote action. Remote action. Light has: Intensity Color (wavelength) Polarization. E = h ν. Light has: Intensity Color (wavelength) = ENERGY Polarization. Remote action Energetics. - PowerPoint PPT Presentation
Transcript of PHOTONS IN CHEMISTRY OUT
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
