Wet SEM Analysis of Quantum dot emulsions - Rice University

The three last Peaks: Cr, Fe, Ni are probably from the stainless steel sample SEM holder. The
rest of the Peaks are from the emulsion and contamination traces of the Water (cleaning sample
Holder with Water).
Figure 5. Energy Dispersive X-Ray Spectroscopy (EDS) of Qdot emulsion: X-Ray Energy
emission spectra, Elemental Analysis, SEM secondary electron mode. The last peak Cr was
probably from the stainless steel sample SEM holder. The Detector picked up Cd and Se
Signals which reconfirmed that emulsion contained CdSe Qdots. The rest of the Peaks are from
the emulsion and contamination traces of the Water (cleaning sample Holder with Water).
3. Conclusion
Test run 1 and 2 showed that no useful data can be obtained with the electron beam pointed in
the middle of the emulsions. Test run 3 and 4 demonstrated that if the electron beam is
pointed at the edge of the sample holder that this area plays an important factor as a Interface
reference point in visualizing the emulsions surface. The different chamber conditions in Test
run 4 did not visualize the Qdot aggregation in the emulsion. However interesting visual
effects in the morphological behavior of the surface of the emulsion exposed to the different
sample chamber condition could be observed and were described in the Experimental section
of this report: The Qdot emulsion seemed to be much more stable regarding the bubble “Pop
corn” and “Strawberry” droplet visual effects. One hypotheses might explain the better
physical stability of the Qdot emulsion when exposed to the heat generated by the electron
beam: The CdSe might act as a kind of conductor conduit guiding the beam right through the
emulsion to the bottom like a lightning rod the lightning to the ground. Whereas the blank/
Control without the electrical conductor is longer exposed to the heat of the beam causing
violent bubbling. The second more likely and reasonable hypotheses is simply by comparing
the blank/ control emulsion to the Qdot emulsion by eye: The Qdot emulsion seemed to appear