Are Quantum Dots Unstable? - Paden Roder

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Discussion Overview

The discussion revolves around the stability of quantum dots, particularly in relation to their absorption and emission of photons. Participants explore the implications of quantum dots absorbing high-frequency photons and re-emitting lower-frequency photons, questioning whether this process indicates instability or a change in mass.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Paden Roder suggests that quantum dots may be unstable because they absorb high-frequency photons and re-emit lower-frequency ones, implying a change in mass.
  • Warren expresses a belief that quantum dots emit more low-frequency photons than they absorb high-frequency photons, questioning the initial assumption about stability.
  • Warren clarifies that all photons travel at the same speed, c, which may relate to the discussion on energy and stability.
  • Paden Roder acknowledges the intent behind his earlier statement about "slower moving" photons, confirming he meant lower frequency.
  • A later reply notes that the excess energy from absorbed photons is converted to thermal energy, suggesting a mechanism for energy dissipation in quantum dots.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on whether quantum dots are unstable. Multiple viewpoints are presented regarding the implications of photon absorption and emission, and the discussion remains unresolved.

Contextual Notes

Participants have not fully defined the terms related to stability and mass change, and there is an assumption that the relationship between photon frequency and energy conversion is understood but not explicitly detailed.

PRodQuanta
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Sandia National lab reported that quantum dots absorb near UV and re-emit at the visible range. It's wavelength shifts to a longer wavelength with 60% efficiency.

Does this mean quantum dots are unstable? Since they add mass to themselves. This makes them something different from what they were initially. I come to this conclusion that they add mass by the knowledge that the quantum dots absorb a high frequency photon and release a slower moving one.

Thoughts?
Paden Roder
 
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I have the feeling the dots emit more low-frequency photons than they absorb high-frequency photons.

Also, all photons move at the same speed: c.

- Warren
 
What is a quantum dot?
 
An effectively zero-dimensional confinement apparatus for electrons.

- Warren
 
You know what I meant (or so I hope) when I said slower moving one. Lower frequency.
Paden Roder
 
The excess energy is converted to thermal (lattice vibrations), and ultimately coupled out through the surface to the surrounding medium.
 

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