Can Visible Light Excite Quantum Dots to Emit Fluorescence?

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SUMMARY

Quantum dots emit fluorescence primarily when exposed to UV light, as visible light does not provide sufficient energy to excite their electrons. The discussion clarifies that while visible light can influence the color observed in solutions containing quantum dots, it does not lead to fluorescence. The phenomenon occurs due to the absorption characteristics of the solution, which can absorb lower wavelengths and transmit higher wavelengths, affecting the perceived color. The example of a fluorescent dye absorbing light at approximately 650 nm illustrates this concept effectively.

PREREQUISITES
  • Understanding of quantum dots and their electronic properties
  • Knowledge of fluorescence and excitation mechanisms
  • Familiarity with light absorption and transmission principles
  • Experience with spectroscopic techniques for analyzing light interactions
NEXT STEPS
  • Research the principles of quantum dot fluorescence and excitation thresholds
  • Explore the role of UV light in activating quantum dots
  • Learn about the absorption spectra of various fluorescent dyes
  • Investigate the effects of solution properties on light transmission and color perception
USEFUL FOR

Researchers in nanotechnology, chemists working with fluorescent materials, and educators teaching concepts of light-matter interactions will benefit from this discussion.

bluejay27
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Quantum dots fluorescence whenever UV light is applied to them. Whenever the UV light is off and visible light hits the quantum dots it posses colors but does not fluorescence. I thought light had to have energy that is equal or greater than the band gap for the quantum dots to emit light. How does emission occur if visible light does not have enough energy to excite the electrons of the quantum dots.
 
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Color can come from the solution absorbing light. For example, I commonly work with a fluorescent dye that absorbs light in the orange-red end of the visible spectrum (peak absorbance ~ 650 nm). Even though the dye emits red light, solutions of the dye appear blue because when light passes through the solution, the lower wavelengths of light are absorbed, while blue and other higher wavelengths of light are transmitted.
 

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