The accompanying image shows photoluminescence from four different samples of CdTe nanocrystals, each embedded in a polymer matrix. The photoluminescence occurs because the samples are being irradiated by a UV light source. The nanocrystals in each vial have different average sizes. The sizes are 4.0, 3.5, 3.2, and 2.8 nm. (a) Which vial contains the 4.0-nm nanocrystals?

Video transcript

Hey everyone, we're asked to consider three vials containing semiconductor nanocrystals, each embedded in a polymer matrix. We're told that each vial amidst a different color of light blue, green and yellow and were asked to identify which vial has the smallest average particle size of the semiconductor. So if we have smaller nanocrystals, then this must mean that we have a greater band gap, which means we have a shorter wavelength. Now let's go ahead and pull up our chart. As we can see right here. Our blue light has the shortest wavelength. So if we were to arrange this, our blue would have the shortest wavelength, followed by our green and lastly followed by our yellow. So the answer here is going to be blue with the smallest average particle size of the semiconductor since it has the shortest wavelength. So I hope that made sense. And let us know if you have any questions.