Week 4+5

June 25, 2023

I missed last week, sorry about that! Week 4 was fairly uneventful, although I did start the new nanoparticle project. The synthesis starts with silver nitrate. The silver is separated from the nitrate in solution. A reducing agent is added to create the silver nanoparticles. Silica is used as the shell.

Because nanoparticles are so small, the only effective way to purify them is centrifugation. After most steps in the synthesis the product is centrifuged for 30 minutes to 1 hour. This can make the process boring and tedious at times, but I find that the final product makes it all worth it.

This is the nanoparticles after a round of centrifugation. The dark spot on the bottom of the tube is where the nanoparticles have aggregated. The solution retains a brownish color from reduced silver staying in solution, the purpose of the centrifugation is to "wash" the product and rid it of impurities.

After the addition of the silica shell this is our final product. These particles are about 20 nm in diameter. This image was taken on a transmission electron microscope (TEM). A TEM shoots electrons at a sample. Lighter areas indicate more transmission of electrons, while darker areas indicate less transmission. The dark dots are the silver core, which has far more electronic interactions than the silica shell. The silica shell still has more electronic interaction than the carbon layer that the sample is deposited on and appears darker.

Currently we are working on gadolinium nanoparticles, which are magnetic. More on that next week potentially.

In other news, I finally went out and did interesting things in my free time. Wednesday was "Fête de la Musique" aka "Make Music Day". Free concerts are held across all across cities in many parts of the French speaking world. In Fribourg alone there were several venues each with local artists playing all day until midnight. It was a great time.

Pictures from 2 of the shows I went to. Both groups were local to the Fribourg area.

Yesterday I went with my neighbor and some of her friends to Mt. Pilatis in Lucerne. The view was incredible. There were paths to hike up, but instead we took cable cars up and the worlds steepest cogwheel railway down. The group had people from all over the world. No two of us were from the same country.