Why Is Spin-Orbit Coupling Selective in Phosphorescence Transitions?

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In summary, the conversation discusses the topic of phosphorescence and the role of spin-orbit coupling in the first transition from a singlet state to a triplet state. The person expresses confusion about whether this coupling also exists between the ground state and the triplet state. The other person explains that in order for phosphorescence to occur, there needs to be both spin-orbit coupling and vibronic coupling between the singlet and triplet states, and also coupling to the radiation field for the transition back to the ground state. They also mention Kasha's rule, which states that vibronic coupling is not as efficient due to the large energy gap.
  • #1
Gavroy
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hi

i have still some troubles to understand phosphorescence:

http://en.wikipedia.org/wiki/Phosphorescence"

wikipedia has a diagram, where an electron in an exicted state that is a singulet state falls on a second level that is a triplet state.

my problem is, that this first transition is explained by spin-orbit coupling. but is it no so, that the ground state and this triplet state should have spin-orbit coupling either?- but in this case, the transition from the triplet state to the ground state should also be possible.

so it is possible to have this coupling just between some states?

sorry about my english.
 
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does nobody have an idea or is there anything wrong with my question?
 
  • #3


Of course there is also spin orbit (SO) coupling between S0 and T0, if not you would not observe phosphorescence.
The point is rather that for the transition from S1 to T0 you need both SO coupling and vibronic coupling while for the transition from T0 to S0 you need both SO coupling and coupling to the radiation field.
As in the case of fluorescence, the vibronic coupling between S0 and T0 is rather inefficient due to the large energy gap (Kasha's rule: http://en.wikipedia.org/wiki/Kasha's_rule )
 

FAQ: Why Is Spin-Orbit Coupling Selective in Phosphorescence Transitions?

What is phosphorescence?

Phosphorescence is a type of luminescence where a material emits light after being exposed to certain types of energy, such as light or electricity.

How does phosphorescence differ from fluorescence?

The main difference between phosphorescence and fluorescence is the duration of light emission. While fluorescence only lasts for a short period of time after the energy source is removed, phosphorescence can emit light for a much longer period of time, even after the energy source has been removed.

What causes materials to exhibit phosphorescence?

Phosphorescence occurs when electrons in a material are excited to a higher energy level by an external energy source, and then return to their ground state slowly, emitting light in the process. This slow return to the ground state is what differentiates phosphorescence from other forms of luminescence.

What are some examples of materials that exhibit phosphorescence?

Some common examples of materials that exhibit phosphorescence include glow-in-the-dark toys, certain types of paints and coatings, and certain minerals such as fluorite and calcite.

How is phosphorescence used in scientific research and technology?

Phosphorescence has a wide range of applications in scientific research and technology, such as in medical imaging, environmental monitoring, and security features on banknotes. It is also used in the development of new materials and technologies, such as organic light-emitting diodes (OLEDs) and photovoltaic cells.

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