Photochemistry

1
Photochemistry
2
????????????? 15 ???????
- ???? ?????????????????????????? -
?????????????????????????????????????????? -
Jablonski Diagram ??????????????????????????? ?
- ???????????????????????????????????????????? -
????????????????????????????????????????
3
Thermochemistry
Reactants
Products
D
A B C D DH ...
????????????????????????? (ground state)
????????????????????????????
????????????????????????????????????????????
???????????????????????????
4
Photochemical Reaction
E hn
M
M
Products
hn UV - VIS (200 -800 nm)
???????????????????????????? (excited state)
?????????????????????????????????????????
??????????????????????????????????????????
??????????????????????????????????????
5
????????????????????????? ??????Ultraviolet (UV)
???? ?????????????????????????????? (VISIBLE)
?????????????????????? ???? ?????????????
???? ????????????????? ???????
6
wavelength
200 400 800 nm
UV VIS
Ultraviolet
Visible
7
- ???????????????? (Synthesis)
- ?????????? (Decomposition)
- ??????????????????? (Isomeric Change)
????????????????????
- ???????????????? (Redox Reaction)
- ??????????????????????? (Polymerization)
8
Synthesis
hn
(C6H5)2CO (C6H5)2CHOH
(C6H5)2-C-C-(C6H5)2
C6H6
benzo- benzhydrol
benpinacol
phenone
9
Isomeric
C6H5
C6H5
C6H5
hn
N N
N N
C6H5
(cis - azobenzene) (tran - azobenzene)
10
Decomposition
O
hn
CH3-CH3 CO
CH3-C-CH3
313 nm
(ethane)
(ketone)
11
PHOTOCHEMISTRY
12
Spectroscopy
Spectrophotometry
??????????????????????????????????????????????????
???????????????????? (electronic wave)
???????????? ??? ???? (????? ??????? ????? ????
???????????)
13
??????????????????
???? plane-polarized ?????????????????????
?????????????????????? ??? ????????????
14
?????????????????? ?????????????????????????????
??? ????? 2 ?????? ???
1. ????????? (wave)
2. ?????????? (particle)
????? ???????? ????????????? ????????
???????????????????????????? ???????
?????? Photoelectric effect
15
?? ?.?. 1905 Albert Einstein
????????????????????????????? ?????????? ???
?????????? ??????????? ????? Photon
?????????????? Planck ??????????????????????????
??
16
?????? 1 ????? ???????????? ?????? ? n
???????????????? hn ??????? 1 ??????? (quantum)
E hn
h ??? ??????????? Planck 6.6262 ? 10-34 J s
17
??????????????????????????? ?????????????????????
???????????????????????????? ??????????????
?????????
?????????????? ??????????????
?????????????
??????????????? (thereshold frequency)
????????????????????????????????????? ???????????
???
18
Electromagnetic spectrum
??????????????????????????????????????????????????
?????????????? ???????????????? ?
??????????????????????? (g -rays)
??????????????????(??????????????????????)
????????????????? (radio wave) ???????????????????
(?????????????????????)
19
max
short
g -rays
Nuclear transition
WAVELENGTH
X -rays
Electronic transition (Inner, middle, valence
shell)
ENERGY
UV
VIS
IR
Molecular transition (vibration, rotation)
Microwave
Spin Orientation
Radio wave
min
long