Formation of Excimer Structures: Explained for Engineers

In summary: This means that the laser output is always the same (ie, a single photon is emitted per transition between levels), regardless of how much Xe2 is in the laser.
  • #1
MartinMan
5
0
Reposting from another section...

Can anyone explain to me how an excimer is formed? Like structure wise?

Considering Xenon.
I've gathered that an excited state Xe*, ground state Xe, and a 3rd body M react resulting in an Xe* excimer + M(carrying away excess energy).

I'm struggling to find how the ground state Xe can have any reaction at all with its full valence band. Any pointers?

Thanks in advance!
PS My physics/chemistry isn't particularly advanced, I'm studying elec. engineering.
 
  • #3
MartinMan said:
Reposting from another section...

Can anyone explain to me how an excimer is formed? Like structure wise?

Considering Xenon.
I've gathered that an excited state Xe*, ground state Xe, and a 3rd body M react resulting in an Xe* excimer + M(carrying away excess energy).

I'm struggling to find how the ground state Xe can have any reaction at all with its full valence band. Any pointers?

Thanks in advance!
PS My physics/chemistry isn't particularly advanced, I'm studying elec. engineering.
Excimers are excited state molecules where the excited state is bound, and the ground state is not bound (or weakly bound). They can be formed in electric discharges, typically under reasonably high pressures (several bar). The high pressures are needed to increase the rate of three-body "reactions" -- e.g. Xe* + Xe + M -> Xe_2* + M.

You are correct that the noble gases are closed-shell, unreactive. This is why the ground electronic state of Xe_2 is not bound. The excited states can have significant binding energies, though. You can think of the reason why, if you think about what Xe* looks like: you have a Xe+ ion core with a weakly bound (Rydberg) electron. The Xe+ has a hole in a p-orbital that can accept an electron from the other Xe (assuming that the Rydberg electron is far away). If you draw the molecular orbital picture for the Xe2* and the Xe2, you can see that the Xe2 has a bond order of zero, while the Xe2* has a bond order of 1/2 (assume that the Rydberg electron is non-bonding).

Excimer lasers are useful because they are a rather clever three-level laser, where the intermediate level (Xe2) automatically disappears when it falls apart to form isolated atoms.
 

1. What are excimer structures and how are they formed?

Excimer structures are molecules or compounds that consist of two different atoms or molecules that are bonded together and have a short-lived excited state. This state is formed when a high-energy photon or electric discharge is applied to the system, causing the electrons to move into higher energy levels. The excited state is unstable and quickly decays, resulting in the formation of the excimer structure.

2. What is the role of engineers in the formation of excimer structures?

Engineers play a crucial role in the formation of excimer structures by designing and building the necessary equipment and systems for creating the high-energy environment required for the process. They also play a key role in optimizing the conditions for the excimer formation and controlling the parameters to achieve the desired structure.

3. What are some practical applications of excimer structures?

Excimer structures have various practical applications in fields such as medicine, materials science, and electronics. For example, excimer lasers are used in eye surgery, and excimer-based polymers are used in microelectronics and lithography. They also have potential uses in drug delivery, sensors, and solar cells.

4. How do scientists and engineers study and manipulate excimer structures?

Scientists and engineers use a range of techniques to study and manipulate excimer structures. These include spectroscopy, microscopy, and computer simulations. By understanding the energy levels and dynamics of the excited state, they can manipulate the structure and properties of the excimer for specific applications.

5. Are there any challenges in the formation of excimer structures?

Yes, there are several challenges in the formation of excimer structures. One of the main challenges is controlling the conditions and parameters to achieve a specific excimer structure. The process also requires high levels of energy, which can be difficult and expensive to generate. Additionally, the short-lived nature of the excited state makes it challenging to study and manipulate the structures in real-time.

Similar threads

  • Atomic and Condensed Matter
Replies
3
Views
1K
Back
Top