Stark-broadening and plasma polarization

In summary, Stark-broadening theory is a concept used in spectroscopy that explains how the randomness and disorder in a plasma can affect the intensity and properties of spectral lines. It is also related to the phenomenon of continuum lowering and can impact reabsorption and coherence in lasers. The controversial idea of plasma polarization shift, which suggests an extra charge inside the emitter wavefunction can shift energy levels, is not supported when electron dynamics are properly taken into account.
  • #1
Jonny_trigonometry
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What is Stark-broadening theory? Does it have something to do with mean free time or mean free path? How does this effect spectroscopy?

How does plasma polarization shift based on the quantum-mechanical impact theory work?
 
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  • #2
A short and very clear exposition is the review published in High Energy Density Physics by
S.Alexiou, Overview of plasma line broadening, High Energy Density Physics 5, 225-233(2009)
http://www.sciencedirect.com/science?_ob=PublicationURL&_ctockey=%23toc%2328561%232009%23999949995%231548168%23FLA%23&_cdi=28561&_pubType=J&_acct=C000059627&_version=1&_urlVersion=0&_userid=83470&md5=df755c8f27215db57f059e90781137d7&jchunk=xxx

Basically broadening has to do with randomness and disorder. Don't look at mean free paths.
It affects spectroscopy in huge ways; for instance an excessively broad line will have so low intensity that it will not be observable(this is one of the components of continuum lowering).
It also affects reabsorption, it affects the coherence properties of lasers and many others.

Plasma polarization shift is a controversial notion, based on a static picture. It is about the extra charge inside the emitter wavefunction that shifts the levels and hence the transition energy. The problem is that that extra charge inside the emitter wavefunction is not a static charge, but plasma electrons flying by. So if one accounts for electron dynamics correctly, it just is not there.
 
  • #3


Stark-broadening is a phenomenon in spectroscopy where the spectral lines of an atom or molecule are broadened due to the presence of an external electric field. This effect is caused by the interaction between the charged particles in the plasma and the electric field, leading to a redistribution of the energy levels within the atom or molecule.

The Stark-broadening theory is based on classical electrodynamics and takes into account the interactions between the charged particles in the plasma and the external electric field. It does not directly involve mean free time or mean free path, which are concepts related to the collisional processes in a gas. However, the broadening of spectral lines can indirectly affect these quantities by altering the collisional cross-sections between particles.

In terms of spectroscopy, Stark-broadening can have significant effects on the interpretation of spectral lines, as it can broaden and shift the lines, making them more difficult to analyze. This effect is particularly relevant in plasma physics, where the presence of strong electric fields can lead to significant broadening and shifting of spectral lines.

Plasma polarization refers to the collective alignment of charged particles in a plasma in response to an external electric field. This phenomenon is described by the quantum-mechanical impact theory, which takes into account the interactions between the charged particles and the electric field on a quantum level. The impact of this theory on plasma polarization is that it predicts a shift in the energy levels of the particles, which can affect the overall polarization of the plasma. This shift can also lead to changes in the spectral lines and broaden them, further complicating the analysis of spectroscopic data in plasmas.

In summary, Stark-broadening and plasma polarization are both important phenomena in spectroscopy and plasma physics, respectively. While Stark-broadening is described by classical electrodynamics and affects the broadening of spectral lines, plasma polarization is governed by the quantum-mechanical impact theory and can lead to shifts in the energy levels of particles and changes in the spectral lines. Both of these effects must be taken into account when studying plasmas and analyzing spectroscopic data.
 

1. What is Stark-broadening?

Stark-broadening is a phenomenon in which the spectral lines of an atom or molecule are broadened due to the presence of electric fields. This can occur in plasmas, where charged particles create strong electric fields that affect the energy levels of atoms and molecules, causing their spectral lines to broaden.

2. How does Stark-broadening affect plasma polarization?

Stark-broadening can lead to changes in the polarization of light passing through a plasma. This is because the electric fields in the plasma can induce the alignment of charged particles, which affects the direction of the electromagnetic wave's oscillations. This results in a change in the polarization of the light passing through the plasma.

3. What is plasma polarization?

Plasma polarization refers to the alignment of charged particles in a plasma due to the influence of electric and magnetic fields. This can result in the plasma having a net dipole moment, which affects the behavior of light passing through it.

4. How is Stark-broadening and plasma polarization related to atomic and molecular processes?

The presence of electric fields in a plasma can affect the energy levels of atoms and molecules, leading to Stark-broadening of their spectral lines. This, in turn, can affect the polarization of light passing through the plasma. Additionally, atomic and molecular processes can also contribute to the generation of electric fields in a plasma, further influencing the level of Stark-broadening and plasma polarization.

5. What are the applications of studying Stark-broadening and plasma polarization?

The study of Stark-broadening and plasma polarization is important in various fields such as astrophysics, plasma physics, and spectroscopy. In astrophysics, it can help in understanding the properties of distant stars and their atmospheres. In plasma physics, it plays a crucial role in understanding the behavior of plasmas in fusion reactors. In spectroscopy, it can provide valuable information about the composition and properties of a plasma.

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