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Photochemistry can be dramatically different from “ordinary” chemistry See example below. Cl. Cl. Ar. Ljósefnafræði ; Dæmi / photochemistry example:. Cl. Cl. Ar. Ljósefnafræði ; Dæmi / photochemistry example:. . . . Cl. Cl. Ar. Ljósefnafræði ; Dæmi / photochemistry example:.

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Photochemistry can be dramatically different from ordinary chemistry see example below

Photochemistry can be dramatically

different from “ordinary” chemistry

See example below


Photochemistry can be dramatically different from ordinary chemistry see example below

Cl

Cl

Ar

Ljósefnafræði ; Dæmi /

photochemistry example:


Photochemistry can be dramatically different from ordinary chemistry see example below

Cl

Cl

Ar

Ljósefnafræði ; Dæmi /

photochemistry example:

.

.

.


Photochemistry can be dramatically different from ordinary chemistry see example below

Cl

Cl

Ar

Ljósefnafræði ; Dæmi /

photochemistry example:


Photochemistry can be dramatically different from ordinary chemistry see example below

-

+

Cl

Ar

Ljósefnafræði ; Dæmi /

photochemistry example:

Cl


Photochemistry can be dramatically different from ordinary chemistry see example below

Cl

Ar

Ljósefnafræði ; Dæmi /

photochemistry example:

Cl


Photochemistry can be dramatically different from ordinary chemistry see example below

Ljósmyndun efnahvarfa;

Nóbelsverðlaunin í efnafræði, 1999

* Sjá: http://www.hi.is/~agust/

* Sjá: http://www.hi.is/~agust/


Hr efnahv

Hr.efnahv.

Gangur og hraði efnahvarfa:

A + BC + D


Hr efnahv1

Hr.efnahv.

Arrheníus: Nóbelsverðlaun 1903

Ljósmyndun efnahvarfa; Nóbelsverðlaunin í efnafræði, 1999

Gangur og hraði efnahvarfa:

A + BC + D

Hraði = k[A][B]; k = Aexp(-Ea/RT); k <= [A] vs t mælingar

Hr.efnahv.


Kenning

1930-1940:

Kenning um skammlíft milliástand:

Kenning

Henry Eyring

Michael Polanyi

#

A..B

1

2

A + B

C + D

# Skammlíft milliástand:

Líftími »tími tengjasveiflu, dæmigert 10-13 – 10-12 sek

1:

2:


Bunur

John C. Polanyi

Nóbelsverðlaun, 1986: Dudley Herzbach

Yuan Lee

1975-1990:

Tilraunir með sameindabunur:

Bunur

Sameinda-

buna

Árekstur

Skynjun

myndefna/

hvarfefna

Hreyfanlegur

skynjari

-Ráðið í eiginleika milliástanda út frá dreifingu / endurkasti sameinda


Ljosm

“Femtósekúndu litrófsgreining”

Nóbelsverðlaunin í efnafræði 1999:

Próf. Ahmed Zewail, Caltech.

1985 -

“Ljósmyndun efnahvarfa”

Ljosm.

Þ.e. Gleypnimælingar milliástanda vs tími fyrir tíma(bil) £10-12 s:

Gleypnimælingar

með ljósleiftrum

10-15 s

AB

CD

A . .B

C ..D

A + B

0,000000000000001 s

C + D


Ver l

Verðl.


Femtol

http://www.its.caltech.edu/~femto/

Femtol.


Hvernig

Of margbreytilegt

/flókið

Hvernig / Hvað?

Hvernig?

A + BC + D

Öll stig hvarfsins koma fyrir samtímis, þ.e.:


Photochemistry can be dramatically different from ordinary chemistry see example below

Dæmi: “½ hvarf”, sbr.: ICN# I + CN, Þ.e.:

I

CN#

Skapa þarf “samhæfðar aðstæður”:


Hvarf

Dæmi: “½ hvarf”, sbr.: ICN# I + CN, Þ.e.:

Gleypnimælingar

ICN#

I +CN

ICN#

Myndað með femtó-

sekúndu LASER-púls

gleypni

ICN

Skapa þarf “samhæfðar aðstæður”:

½ hvarf

I

CN


Icn tilr

Framkvæmd:

ICN-Tilr.


Icn ni urst

Gleypni-

Mælingar:

Niðurstöður:

Nánar:

ICN#

I +CN

ICN-niðurst.

ICN


Photochemistry can be dramatically different from ordinary chemistry see example below

(a)

(b)

[NaI#Na..I# ]Na + I

NaI

NaI

(a)

NaI#

(b)

Na


Stilbene 1

Stilbene(1)


Stilbene 2

Stilbene(2)


Ih oco

IH..OCO [I..H..O..CO]I+HO+CO

IH+OCO

Van der

Waals

“Sameindir”

Spýtt-

kæling

Sameinda-

buna


Cyclob

Cyclob.

C4H8C4H8#C2H4 + C2H4

???


C2f4i2

Rofnun tetrafluordijoðetans:

C2F4I2

C2F4I2C2F4 + 2I:

.

I

F

I

F

F

?(1)

F

C C

C C

F

.

F

F

I

F

I

.

I

F

F

I

F

I

F

F

.

F

?(2)

C C

C C

C C

.

F

.

F

F

I

F

I

F

F

I


Mynataka

mynataka


Photochemistry can be dramatically different from ordinary chemistry see example below

5


Photochemistry can be dramatically different from ordinary chemistry see example below

6


Photochemistry can be dramatically different from ordinary chemistry see example below

7


Photochemistry can be dramatically different from ordinary chemistry see example below

8


Photochemistry can be dramatically different from ordinary chemistry see example below

9


Photochemistry can be dramatically different from ordinary chemistry see example below

10


Photochemistry can be dramatically different from ordinary chemistry see example below

Reactioncrosssection:

A + M ???

M1 + M2 ???

A + B C + D


Photochemistry can be dramatically different from ordinary chemistry see example below

Cross section = s = <d>2p

Reactioncrosssection:

A + M ???

M1 + M2 ???

A + B C + D

d

But ions:


Photochemistry can be dramatically different from ordinary chemistry see example below

+

+

-

-

-

+

-

+

+

+

F µ 1/r2

But ions:

Reactioncrosssection:

A+ + B C + D


Photochemistry can be dramatically different from ordinary chemistry see example below

+

+

-

-

-

+

-

+

+

+

But Ions:

Reactioncrosssection:

A+ + B C + D


Photochemistry can be dramatically different from ordinary chemistry see example below

+

+

But ions:

Reactioncrosssection:

A+ + B C + D

Collision frequency much larger


Photochemistry can be dramatically different from ordinary chemistry see example below

Ions:

+

Collision cross

section =

s >> <d>2p

Reactioncrosssection:

A + M ???

M1 + M2 ???

A + B C + D

d


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