Radiation absorption by an atom

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Discussion Overview

The discussion revolves around the absorption of radiation by atoms, specifically focusing on the hydrogen atom and the implications of shining monochromatic light of specific energies on atomic energy levels. It explores concepts such as energy level transitions, scattering, and the nature of vibrational energy in atoms and molecules.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant explains that when light is absorbed by an atom, it stimulates electrons to jump to higher energy levels, which are quantized.
  • The same participant questions whether a hydrogen atom would absorb radiation of 10.3 eV, given that the transition from n=1 to n=2 requires 10.2 eV.
  • Another participant notes that light can also scatter off atoms, not just excite them.
  • A further reply clarifies that scattering involves a transfer of energy and momentum from the photon to the atom, likening it to a billiard-ball collision.
  • A participant seeks confirmation on their understanding of scattering and raises the question of whether the excess energy from scattering could lead to vibrational energy levels, and if these levels are quantized.
  • The same participant inquires whether the excess energy could also contribute to translational or rotational energies of the atom or molecule.

Areas of Agreement / Disagreement

Participants express differing views on the implications of energy absorption and scattering, with some uncertainty regarding the effects of excess energy on vibrational, translational, and rotational states. No consensus is reached on these points.

Contextual Notes

The discussion includes assumptions about energy quantization and the nature of atomic interactions with light, which may not be fully resolved. The relationship between vibrational energy levels and other forms of energy is also not definitively established.

jaumzaum
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When we shine light on an atom, it can absorbs this radiation, stimulating its electrons to jump to a more energetic energy level. This lasts too little time, and when the electrons come back to their original (fundamental) energy level, they emit the same energy they had absorbed before. This energy levels, though, are quantized. And by what I've understood, the atoms can only ABSORB and emit some discrete frequencies. So, I'm confused about the following:

Consider the hydrogen atom.
To pass from the n=1 to the n=2 energy level, we need a radiation of 13,6 (1/1² - 1/2²) = 10,2 eV.
What would happen if we shine a monochromatic light of energy hf = 10,3 eV?
Would the atom absorb that radiation?
 
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Light does not just excite atoms, it also scatters off them.
 
Bill_K said:
Light does not just excite atoms, it also scatters off them.

What does it mean?
 
Scattering is a billiard-ball collision in which some of the energy and momentum of the photon is transferred to the atom. You might take a look at this Wikipedia page.
 
Bill_K said:
Scattering is a billiard-ball collision in which some of the energy and momentum of the photon is transferred to the atom. You might take a look at this Wikipedia page.

Thank you. I've read your page about the topic, can you tell me if I understood it right?

By what I've understood, the excess of energy is absorbed by the atom, making it vibrate in different levels of vibration (rayleigh scattering). Is this right?
Are this vibration levels quantized too? By what I know so far, vibration is a type of movement that does not change the mass center of a molecule. Could this excess of energy be added to the translational or rotational energies too?
 

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