21 Jun Cricket Kees, U of Houston, Week 3

My third week at the University of Houston has just ended, and I am super excited to say I got a lot done. I was able to do lots of different experiments and use different machines and tools to help the other grad students and post-docs to their projects. I got to work with the spectrometer, helping Baldelli re-align the lenses and mirrors to get better signals of the sample, which was very difficult and required lots of precision. Furthermore, I got to learn a little more about the projects Baldelli sent me to research about before we arrived to Houston, and I got to help make practice samples for them. In more detail, my week in the lab started off with attempting to continue making more metal films, with the evaporator.

The layer that chromium leaves in the evaporator!

Zane had been working on adjusting the machine, checking for any leaks, since the pressure was still high (around 10^-5) when we want it to be around 10^-6, to make good, clear films. Troubleshooting with a bad pressure while making my films was difficult, but I managed to get samples of silver and chromium over the week. All of the samples Baldelli has had me make are ones that are 100 nanometers thick, so they take lots of time to make, especially when having to use a low rate of heat to not melt the metal too fast. Besides the films, I got to use my samples with the spectrometer, to see the frequency waves that the different metals give off in the form of films. To be able to see it, I first had to put my samples in a jar with cyanide, which helps to be able to see the structures of the metals more clearly. When cyanide molecules bond to a metal, like silver or copper, it reacts, since its extremely sensitive to that metal molecule, and therefore act as an “absorbant” to be able to read the structure of the metal to the spectrometer camera. Troubleshooting with the spectrometer to actually give us a reading of the metal was the real hard part. The “signal” is the frequency waves in a spectroscopy graph, which tell us the elements in the molecule, as well as the characteristics of its movement when excited.

vacuum for “photoresist master” aka the object shaping the PDMS

The vacuum for PDMS that removes air bubbles and solidifies the material

After we had trouble with the spectrometer, we moved onto a different experiment, something that resembled a lot of what I read before coming to Houston, what Baldelli thought I could do for my personal project ( in between making metal films and working with spectrometer reading). I worked with Navodha to make a PDMS ( which acts like a stamp). It took a while to make this rubber-like material, which is usually created in different shapes to produce patterns on metal films with alkanethiol (what I previously talked about in my other blog). Since this is just to practice, we made a square PDMS, and we will later run the rest of the experiment, by layering a coat of alkanethiol over the PDMS, which bonds to the metal film (we would use gold for our specific experiment) and then get a visual pattern of the shape of the PDMS stamp onto the metal film. This process, often refered to as micro-contact printing, takes a lot of specific steps in order to create it. PDMS is first mixed as a liquid, and then poured into a small, cleaned dish that has a “photoresist master” giving the shape to the PDMS. So far, this is what I have done for my lab work.

When I am not doing work, I am usually hanging out with my friends! This week I was able to get a pass to go to the rec. center on campus, which was super fun! I went on Saturday, once I got out of the lab, and played volleyball and basketball with a couple of my friends! I got out at around 3 on Saturday, so it gave us lots of time to visit the rec. We wanted to swim, but the heavy rain prevented us from being able to visit the outdoor pool! I still am recovering from being sick, but hopefully I start to feel better soon. I don’t have much free time, so being able to go to the recreation center was great. My brother and dad also visited, and I had a good time seeing them and getting dinner, as well as showing them around the campus. Overall, I have had a good time working, and I hope to learn even more and use my skills to help in Baldelli’s lab.