2. Main Points to be Discussed
1. History
2. Jablonski Diagram
3. Features of Jablonski Diagram
4. Transitions
5. Absorption of light
6. Emission of light
7. Methods of emission of light
8. Time Scale
9. References
3. History
Alexander Jablonski was a Polish Physicts
He was know for the study of Molecular
Absorbance & Emission of light.
He developed a Written Representation
about consequences of applied photons.
That scheme was refed as Jablonski
Diagram.
4. Jablonski Diagram
“Relaxation mechanism for excited sate molecules”
It features the Energy levels within
a molecule where Valance electrons
could be excited.
It is a diagram that illustrates the
Electronic States and the
Transitions between them
5. Features of Jablonski Diagram
Energy is on vertical axis
Columns are present on horizontal axis that represents a specific Spin
Multiplicity for a specific Specie.
Spin Multiplicity is equal to the no. Of possible orientation of total spin
Columns contains Electronic Energy State
Singlet State (S)
Triplet Excited State (T)
The Thicker lines explain the Electronic Energy Levels.
The Thinner lines denote various Vibrational Energy States.
As Electronic Energy States increases, the difference between energy
become less continuously
Transitions Between States is Illustrated by two type of Arrows
Straight Arrows
Wavy Arrows
6. Transitions
Two types of transitions are
important in discussion of jablonski
Diagram
Absorption
Emission
7. Absorption of Light
The absorbance of a photon of a particular energy by the molecule result in migration of electrons from
lower energy level to higher energy level (Excitation)
This is indicated by a Straight Arrow Pointing Up.
Only certain wavelengths of light are possible for absorbance, that have energies that correspond to the
energy difference between two different energy states of a particular molecule.
Absorbance is a very fast Transitions, on the order of 10-15
8. If Absorbed Photon contains
more Energy then necessary for
transition, the excess energy is
usually converted int vibrational
and rotational energy
9. Emission Of Light
Excited state are shot lived
The molecule exists for Nano seconds in this
excited state
Process of relaxation of excited electrons is known
as Emission.
10. Methods of Emission
Relaxation of the electrons of excited state can
take place by number of methods.
That are:
Vibrational Relaxation and Internal
Conversion
Fluorescence
Intersystem crossing
11.
12. Vibrational Relaxation and Internal Conversion
Migration of electrons from higher Energy State to Lower
Energy State by the loss of absorbed Energy is called
relaxation
It is indicated as Curved Arrows Between Vibrational
Levels
If relaxation occurs between Vibrational Levels in same
Electronic State, then This phenomenon is called
Vibrational relaxation
This process is also very Fast and takes place between 10-14
to 10-11
13. If the Vibrational Energy levels are strongly
overlapped to electronic energy levels then
Internal Conversion Takes place
This overlap of Vibrational Energy levels to
Electronic Energy levels is due to increase in
Energies, as energy increases they came nearer to
each other
If relaxation occurs between Vibrational levels
from one higher Electronic state to another
Lower electronic state, then this phenomenon is
called as Internal Conversion
It has same time frame as Vibrational Relaxation
14. Fluorescence
Migration of electrons from Higher energy state to
lower Energy state by emitting photons
It is indicated as a Straight line going down on the
Energy axis between Electronic States
Fluorescence is a slow process 10-9 to 10-7
It is most often observed between the First Excited
electro state and the Ground State.
15. Intersystem Crossing
The electron changes spin multiplicity from
an excited singlet state to an excited triplet
state
This is indicated as a Horizontal, curved
arrow for one column to another.
This is the slowest process
After reaching at triplet excited state, the
electrons come back at ground state through
phosphorescence.
16.
17. Time Scales
Jablonski diagram shows what sorts of
transitions that can possibly happen in a
particular molecule.
Each of these possibilities dependent on
the time scales of each transitions
The faster the transition , the more likely
it is to happen
18. References
1. H. H. Jaffe and Albert L. Miller "The fates of electronic excitation energy" J. Chem. Educ., 1966, 43 (9), p
469 DOI:10.1021/ed043p469
2. E. B. Priestley and A. Haug "Phosphorescence Spectrum of Pure Crystalline Naphthalene" J. Chem. Phys. 49,
622 (1968), DOI:10.1063/1.1670118
3. https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Spectroscopy/Electronic_Spectroscop
y/Jablonski_diagram
4. https://en.wikipedia.org/wiki/Jablonski_diagram
5. https://www.slideshare.net/AZCPh/jablonski-diagram-physical-chemistry?qid=d38e87d8-53c8-44ee-a7d2-
e65501a65d70&v=&b=&from_search=3
6. https://www.olympus-lifescience.com/en/microscope-resource/primer/java/jablonski/jabintro/
