Quantum Dots

Today I had a look at the quantum dots under table lamp light and with the green 532nm laser. I wasn't sure whether to use the HeNe laser or not (with or without filters) so that will be for another day. Here's the basic characteristics I observed -

Some of the screenshots I took are shown below. (Click for larger - and more informative - versions!) Fig. 1 shows the spectra obtained using 532nm light and Fig. 2 shows the results due to illumination with a table lamp. Interesting to note that small 532nm peak for the green laser emission due to my shoddy alignment of the laser, quantum dots and spectrometer. The absorbtion range of the quantum dots is relatively wide and this yields a large wavelength-spread in emission (see images on the right).

Fig. 1: 532nm Absorption

Fig. 2: Table Lamp Absorption

I also took spectra with the room light on. The weaker intensities are explained by the losses in intensity due to the isotropic radiation given out by the lightbulb. On the other hand, it is possible to see a hint of the emission curves already obtained through laser illumination.