WHAT HAPPENS WHEN A MOLECULE ABSORBS LIGHT?

4 different fates of absorbed light are presented in the next slides

1) INTERNAL CONVERSION

2) INTERSYSTEM CROSSING

3) FLUORESCENCE

4) PHOSPHORESCENCE

S0

S1

T1

A = ABSORPTION

R1

R = RADIATIONLESS PROCESS

IC

R2

INTERNAL CONVERSION LIGHT CONVERTED TO HEAT

Radiationless transition between states withthe same spin number

S1 S0

S0

S1

T1

A = ABSORPTION

R1

R = RADIATIONLESS PROCESS

ISCT

R3

ISCS

R4

INTERSYSTEM CROSSING LIGHT CONVERTED TO HEAT

Radiationless transition between states with different spin number

S0T1

S0

S1

T1

A = ABSORPTION

R1

R = RADIATIONLESS PROCESS

F

FluorescenceRadiational transition between states withthe same spin number

S1 S0

S0

S1

T1

A = ABSORPTION

R1

R = RADIATIONLESS PROCESS

ISCT

R3

P

P F>>

Phosphoresence Radiational transition between states withdifferent spin number

S0T1