Question

How does the size of the particles affect their optical properties?

Answer 1

Energy gap of the particles is inversely proportional to the radius of the particle. So, the particles with a small radius, will have higher energy gap will tend to emit high energy wavelength, small wavelength which will be closer to the visible spectrum of violet, indigo and blue colors.

With the increase in size, the band gap energy will reduce and lead to higher energy wavelength, which will be closer to the end of visible spectrum mainly orange and red colors.

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