Question

A quantum dot emits light at 600 nm. If the particle size is reduced, the emitted wavelength will:

• A. Increase
• B. Decrease
• C. Remain same
• D. First increase, then decrease

Hint:

As the size of a quantum dot decreases, the emitted wavelength shifts to shorter values due to increased energy gap between the electronic states.

Answer 1

The Correct Option is B

In quantum mechanics, when the size of a quantum dot is reduced, its energy levels become more quantized due to the increase in quantum confinement. This effect is known as the quantum size effect. As the particle size decreases, the energy gap between the valence and conduction bands increases. This, in turn, results in the emission of light at shorter wavelengths.
For a quantum dot emitting light at 600 nm, reducing the particle size causes an increase in the energy of the emitted photons, thus decreasing the wavelength of the emitted light. This phenomenon is a direct consequence of the reduced size causing stronger confinement of the electrons and holes.
Therefore, the correct answer is: Decrease.