Absorption cross sections of hydrogen ions

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Discussion Overview

The discussion revolves around the absorption cross sections of positive hydrogen ions, specifically seeking values for certain wavelengths including the H-alpha line. Participants explore the distinction between neutral hydrogen and hydrogen ions, as well as the challenges in finding reliable data.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant requests specific values for the absorption cross sections of positive hydrogen ions, particularly for the H-alpha wavelength.
  • Another participant provides a link to a resource that lists spectral lines of hydrogen but does not address absorption cross sections.
  • A participant clarifies that the H-alpha line pertains to neutral hydrogen, not positive hydrogen ions, indicating a misunderstanding in the initial request.
  • A later participant expresses confusion regarding the absorption characteristics of positive hydrogen ions when exposed to a broad range of wavelengths and seeks clarification on which wavelengths would be absorbed and their corresponding absorption cross sections.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there is confusion regarding the distinction between neutral hydrogen and hydrogen ions, and the specific data requested remains unresolved.

Contextual Notes

The discussion highlights limitations in available resources for absorption cross sections and the need for precise definitions when discussing hydrogen species.

Raezeman
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hello,

i need the values for the absorption cross sections of positive hydrogen ions for a specific set of wavelengths, Halpha to start with. At first i thought finding this on the web was easy, but turns out to not be trivial at all. If you can help me, i also need the (reliable) source where it comes from, a value alone will help me for a brief moment, but will bring me back to the problem in the long run (i think the scientific community will burn me if i try to publish something like 'i got this value from someone on an online physics forum')
 
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euhm, this chart seems to just give spectral lines of hydrogen, while what i need are absorption cross sections, i.e. the measure of probability that the hydrogen ion absorbs a photon, this being dependent on the wavelength. I need this for a specific set of photon wavelenghts, one of which being 656.28 angstum (the Halpha line)
 
oops
 
Raezeman said:
hello,

i need the values for the absorption cross sections of positive hydrogen ions for a specific set of wavelengths, Halpha to start with.

Um, H alpha is the line for neutral hydrogen atom, not positive hydrogen ion!
 
ok wait, I'm getting confused, or mixing up my basic physics, so let me go more broad:
Let's say we have a postiive hydrogen ion being radiated by light with a very broad wavelength range. What wavelengths will get absorbed and what is the corresponding absorption cross section?
 

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