The accompanying image shows photoluminescence from four different samples of CdTe nanocrystals, each embedded in a polymer matrix. The photoluminescence occurs becausethe samples are being irradiated by a UV light source. Then anocrystals in each vial have different average sizes. The sizes are 4.0, 3.5, 3.2, and 2.8 nm.
(a) Which vial contains the4.0-nm nanocrystals?
(b) Which vial contains the 2.8-nmnanocrystals?
(c) Crystals of CdTe that have sizes that are larger than approximately 100 nm have a band gap of 1.5 eV. What would be the wavelength and frequency of light emitted from these crystals? What type of light is this?

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