Summary+of+research+11-15

Equipment: Portable STM- first instrument used, time used gradually lowered in favor of AFM; Becky and Lynda taught me how to use it Annette’s STM- second scope used; used on a limited basis, some images in the summer; most experience was with Sean, observing how to use it the differences from the portable Portable AFM- started using during school year; now primary scope; Valerie taught me how to use it Val’s AFM- I used Valerie’s AFM only a few times, mostly because it scans a different size area than the portable AFM

June: Began on 28th. First days were an intro into how the scopes create images, how to interpret them, and how to operate the scopes.

July: I began scanning on the portable STM early in the month, first with Lynda, then by myself. I also spent a good deal of time with Sean on Annette’s scope. Through Sean, I learned not only how to use the scope, but how to optimize settings, and what to look for in scans. The images on the scope are slightly different from what I was doing on the other scope (namely in dimensions, depth, etc.), but they were similar enough that I was able to use that knowledge with the portable scope. Several times during July I went over to Jordan with Becky and Sean and helped with the nanotechnology seminars. The first was for 7-12th grade teachers, and the second was for K-6th grade teachers. These were opportunities to explain what I was doing in my research to a group of people less familiar with the subject. Also, I went to several talks, in Stepan and Niewland. These were over various topics, not really related to my research. However, they were interesting and informative.

August: The first two weeks in August were a “break” for me, as I did not come into the lab. I worked out with Becky that I would come in Mondays and Tuesdays, from 3:30 to 6 each day, adding up to 5 hours per week. I started the last week in August, and just picked up right where I had left off. I continued scanning with the portable STM and was introduced to the AFM, learning how it was different from the STM and how to use it. During August, I also learned how to process images in MATLAB.

September: I continued using the STM and AFM, but was also introduced to the stationary AFM in the basement of the Radiation Laboratory. There were several more talks that I went to, again over various topics.

October: I continued scanning, almost entirely on the portable AFM, with some portable STM scans as well. I also stated building a new laser for various experiments. Sean made one last year, and the one I’m making with Becky is similar, but with several improvements. Specifically, the new laser is a different wavelength than the old; it runs on a different type of battery (AA vs D); it has better controls and outputs; and it has a LED that is on when the voltage is above a certain mark. This is helpful as it not only tells us when to change the battery, but it also helps us determine the energy of the laser and from that determine its impact.

November: I continued scanning on the AFM, with some limited STM interactions.

Where I have been: My work so far has consisted of learning various microscopes and getting images of the sample I either made or were made for me. In general, I have been working with gold, specifically Au (III), gold cut in a specific pattern. The benefits of using it are: gold has a low sticking coefficient, meaning not many foreign particles stick to the surface, allowing the sample to last a long time and give good scans. Some of the samples for the STM were coated with octanethiols, a self-assembling monolayer consisting of a chain of 8 carbon atoms with one sulfur atom on the end. These are used to better define where the alpha particles impact. None of the samples scanned on the AFM have had octanethiols applied. The samples I have used have had one of two treatments: they have either been annealed and then exposed to alpha particle bombardment from Polonium-210 for a certain amount of time, or they have just been annealed, leaving “clean” gold. Possibly the largest aspect of my research has been studying the difference between the exposed gold surface, with possible alpha-particle impacts, and the clean gold, with no impacts. The goal of this is to determine what kind of impact the alpha-particle has; meaning, does it make a crater when it hits? If so, how big is the crater? What is the frequency of these impacts? At first, the samples I used were only exposed for several hours, maybe a day. More recently I have been using samples exposed for days, even a week or two. The reasoning behind this is that the more time exposed, the more alpha-particles are emitted by the Polonium, and more chance of impacts. The use of various types of microscopes has benefited my research greatly. Instead of being confined to a certain scan area size and type; I have gone from STM, with a smaller scan area to AFM, with a much larger scan area. This has allowed me to observe similar features under very different aspects.

Where I am now: Right now I am working primarily on the portable AFM. Occasionally I have some time on the portable STM, but it has been greatly reduced from the summer. I am still scanning Au (III) bombarded by Polonium-210. At the same time, I am working on the laser, with the hope of finishing, testing, and using it soon. Also, the time differences in exposure were meant to change the amount of interactions between the alpha-particles and the surface. Overall, the images have looked relatively similar, with a couple of exceptions. The sample exposed for less time usually have less extreme features, and the samples exposed for longer sometimes have deeper “canyons”, higher points, and more interference. One example in particular had a remarkably circular area of extreme interference. There was so much interference that the area was almost impossible to scan. I took images of areas surrounding the disrupted area, then images of the area itself. (10510AE to 10510AI).

Where I am going: In all likelihood, I will continue scanning with the AFM for the foreseeable future. The laser I am currently working on cannot be used in together with the portable AFM, so to use it, therefore I will have to use Annette’s scope, because it is setup in a less cramped way, with more open spaces for foreign devices. I will likely become more independent in my research, especially with making samples and working on other projects. I also hope to go back through and process all the images I have taken up to this point. I have many from the summer done, but few if any from the school. My plan is to catch up and process all of the ones I have so far in MATLAB, and in the future be more regular about processing images, hopefully I’ll be able to use it once a month, which would help keep images on my Wiki and also serve as a comparison to the images at that times.