Au and Ag colloids

Exams have kept me busy this week but I have read some interesting papers. The papers have clear diagrams of the experimental setup used and some nice TEM images of the nanoparticles that were produced. Both papers I have posted to the ctools page use a similar setup to ours. One setup does use a magnetic stirrer to mix the sample with the intention of having the particles be exposed to multiple pulses to narrow the size distribution and try to get rid of large agglomerates. They also aged the colloids for a few months then evaluated the sizes again. The aging narrowed the size distribution and reduced the number of large agglomerates. I think it would be interesting to see if this is actually due to time or if centrifuging a sample would have the same effect.
The other paper details why the colloids are stable. They say that the colloid is so stable is because the zeta potential is large (-35mV). This means that the Au nanoparticles in water are charged and thus repel each other in water. This electrostatic repulsion keeps the particles separated and thus they do not clump together and precipitate out. I am interested to see if other papers claim that aging does narrow the distribution of sizes and I will search for a bit information about about the zeta potenital and the stability of the nanoparticle colloids.

Read some more papers

I have been trying to catch up on homework from being sick. I have gotten to read some of the papers that I found the other week. I found one that detailed a two perpendicular pulses to make nanopartices. They do not use fs lasers and so it may still be worth repeating. I have also found a paper that details how they put the particles on a TEM grid. I have also found an interesting paper about a significant increase in thermal conductivity of water by suspending a small amount of Au nanoparticles. I plan to continue reading papers and meet with Ryan to make some nanopartices. I have been accepted for the SURE program put on by Rackham which will let me do research here this summer.

Found some papers

I am feeling somewhat normal now and I used the search terms from an article that I have previously read and it yields much more relevant results. I have found 20 possible articles from the first 100 results. Using my "old" search terms I was finding around 5-10 possible articles per 100 search results. The new and improved search terms will make future searches more productive and less time consuming. Next I will read the bunch of papers from my latest search and reschedule time with Ryan to make some nanoparticles.

Not been feeling well

I have been ill since the end of last week and have not been doing much.

Paper searches

       This morning I met with Ryan. He has read the paper about irradiating a wire sample end on; we concur with Steve that the paper is a bit sketchy. However, we are intrigued by their setup and would like to attempt to repeat it. Ryan and I discussed a method to use 50um thick films and irradiate them from the side in order to approximate an end on wire hit. We are interested in doing a pump-probe experiment in order to image the ejecta plume and confirm a difference between that and a bulk sample, something that was lacking in the paper we read. Later, Peter brought to our attention that one of our mirrors that directs the beam to the lower level lab was not very reflective. So we found some unused mirrors and I got to swap them out and use the power meter to find the most reflective mirror. Most of the ones we found were for the incorrect wavelength or severely damaged. With Peter's assistance and some closer inspection we found out that the original mirror was polarizing and this was the reason for the low power readings. With some rotation of that mirror we were able to get a better power reading and decided to leave it as none of the possible replacements were more reflective.

       Last week I finished reading three papers, two of which I presented at last weeks group meeting. The first compared nanoparticles produced from a bulk target and a wire irradiated end on. The second was about how the number of papers containing "laser" and "nanoparticle" has dramatically increased in the past few years. I was most interested in the search terms that are detailed in the paper. These should help me find more and better papers the next time I search. That paper also had a list of the most cited works that I think I should look through. The third paper that I read was about getting Silver nanoparticles in amorphous Carbon and Aluminum Nitride. They used Pulsed Laser Deposition to make their nanocomposites. I do not find this very relevant to me as there is not much about making nanoparticles but I think that Casey should read it as it seems to be quite relevant to his research.