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My last week at NIST was rather relaxed. Most of the time was spent drafting and revising my presentation. We’d been giving weekly, 1-slide updates to the division, so I already had a good amount of material in power-point form. This week’s meeting was changed to today so that we could spend the time discussing our presentations. I also gave a rehearsal run to Dr. Hacker, and it looks like I’m well within the recommended time frame.
The beach trip was lots of fun, for the most part. I hadn’t been to the ocean for quite some time, so it was nice to swim in the waves again. Unfortunately, when we were all ready to leave on Sunday Carl’s car wouldn’t start. We jumped it a couple of times but it kept stalling out while idling. Since there are a lot of stop signs and red lights between Ocean City and D.C. he couldn’t drive the car back. Also, since it was a Sunday, none of the mechanics were open. He got the car towed and we all sat down over pizza to figure out how to handle the situation. In the end we found a cheep motel and got a room for four for a night. Linda, Foha, Shane, and Carl volunteered to stay, as most of the other interns really needed to go into work on Monday.
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After several days of troubleshooting, we still cannot obtain a signal through the lock-in amplifier. Since my internship is coming to a close soon, we’ve decided to focus on the DC bias data and analysis. Since our presentations are rather quick, I wouldn’t have had enough time to thoroughly present both the DC and AC bias research anyway. With this audience it’s more important to spend a few minutes explaining what exactly FTIR is and why we’re using it on P3HT than to just throw up a bunch of data.
I started my presentation today and hope to put the final touches on it early next week. I’m also looking forward to the tours the interns have planned next week. We’ll be going to NASA and to Capital Hill. On the more social side of things, Amy had a few of us over to her parents’ house for a cookout. Her parents weren’t around, but we did get to meet her sisters and another student who’s staying with them for the summer. We’ve also planned a trip to Ocean City this weekend as a sort of last hoorah. Last count we had 8 of the 12 interns planning to go.
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Since we haven’t been seeing any bias-dependence in our P3HT spectra, Dr. Hacker and I decided to try retaking some older data to make sure our sample was still active. We determined that our sample was still active, but we also saw that our data with the lock-in was far too similar to our data without the lock-in. It turns out our detector software was still configured to use the internal channels instead of taking its data from the input port. Oops!
Now that we have our signal going through the lock-in, we’re having trouble configuring the lock-in to give us anything more than noise. Also, it looks like the lock-in distorts lower-frequency signals, which is bad because P3HT is more responsive at lower frequencies. We are also going to wire up a plain Silicon sample to compare to our P3HT. Silicon is the material we use to obtain our electrical connections with the P3HT sample, so if we ever see a spectral response we want to be able to make sure it’s from the P3HT and not the Silicon.
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In the 4th of July craze I completely failed to make an entry last week, so I’ll be covering two weeks this entry. These past two weeks I have continued taking spectra of our gold-covered P3HT (Poly 3-Hexylthiophine) sample under biases of varying frequencies and amplitudes. The applied biases have ranged from 0.1V to 1V, with frequencies ranging from 40Hz to 100kHz. Unfortunately I still have not observed any bias-induced responses in the IR spectra.
I also took a couple of days off this past week to visit with family. My mom and both sisters came into town, so we spent some time at the American History Museum and the National Spy Museum. The American History Museum has too many exhibits to do in one day, so we only got to see part of it. We did get to see the Science in America exhibit, which was a lot of fun. They have a fun, interactive section on inventors, and another interesting section on robots. I also got a chance to see Old Town Alexandria with my family. The coolest part of the visit was a street performer playing patriotic songs on a set of 40 or so glasses of water. It was quite amazing to watch.
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I got sick with a high fever on Sunday, which caused me to miss 3 days of work. I didn’t get in to NIST until Thursday of this week. Fortunately, Dr. Hacker was able to take some DC-bias data with the gold-covered P3HT sample while I was gone. She had a couple of data sets that still weren’t analyzed, so most of Thursday was spent crunching numbers in Igor. In the afternoon, Dr. Hacker and I hooked up the lock-in amplifier. I was able to take a few AC-bias data sets Thursday afternoon and finished the rest on Friday. Next week I’ll be doing some more number crunching with the AC-bias data.
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We got some new P3HT samples in on Friday, so I took transmission spectra for them. I also got my computer set up. After a lot of wrangling with the bureaucratic system I now have access to the NIST network and a NIST e-mail account. We’ve also started organizing a tour for the other interns. We’re planning to have it in the afternoon on July 2nd. Amy and I can each give a walkthrough of our own labs, and Dr. Suhle, the group leader, has offered to give the interns a tour of some of the other labs in the EEEL group.
Later in the week we had one of our P3HT samples coated in gold so that we can take spectra with bias. I took a reflection spectrum with the new gold-coated sample and it matched nicely with the absorbance spectra. Next week I’ll try spectra with both the DC and AC bias configurations. I also managed to finally install the Igor software I need on the computer in my office. The computer’s CD drive wasn’t working, so I had to borrow one from another computer. Hopefully the IT department can get me a new CD drive so I don’t have to keep popping drives in and out of the computers whenever I need to install something.
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I’ve finally gotten the hang of running the FTIR machine and all the related software. I also have a much better understanding of the process of FTIR spectroscopy and what our data means. Unfortunately we still don’t have the new samples we want to look at, so I’ve spent some time looking at old samples just to familiarize myself with the process. I took a couple of data sets and compared them to some scans that Sean did with the same sample last week. The scans are in good agreement, which tells me that I’m handling the collection and analysis process correctly.
A lot of this week was spent getting new things. I have a computer now, though it only came in at the end of the day on Thursday so I haven’t set it up yet. I also have a NIST ID badge, which lets me enter buildings without having to wait until someone else comes along. And we just set up a lock-in amplifier so that we can take some Charge Modulation Spectroscopy (CMS) measurements. I’ll be testing out the CMS setup next week.
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This past week was almost entirely spent getting things ready. We started Tuesday with an orientation, which included a visit to NIST to meet our advisors. When my advisor took me to the laboratory I’d be working in, the first thing I noticed were dozens of little magnets all over the place. The walls had metal in them and all of the equipment stands were metal, so the group used magnets as a convenient way to hold things or to hang things up. Unfortunately, I have a pacemaker. After spending much of Wednesday with my advisor running a Gauss meter through the lab, I ended up moving to a completely different laboratory.
The downside to this incident was the time loss. Due to the change in labs I had to wait another day before I could begin learning how to use all of the equipment. On the plus side, I’m now collaborating with another intern from the SURF program named Sean. Sean is an electrical engineer. His program started a week before ours so he was able to walk me through all the laboratory procedures. I’m really looking forward to working with Sean this summer. Most of my previous research experience has been very independent, so I’m glad I can try working with a partner this summer.
There’s a lot of administrative overhead at NIST, so getting started has been rather slow. I still don’t have the ID badge you need to get into the buildings, and I still don’t have a computer at my desk. Both of those should be coming next week, but the delay has certainly slowed things down a bit. I’ll be working with IgorPro, a language I’ve never used before, but without a computer I haven’t had a chance to learn it yet. I’ve been occupying myself by reading up on FTIR spectroscopy. We’ll be using the spectroscopy to analyze the effects of applied electric fields on the molecular structure and oscillations of various molecules, so I need to familiarize myself with the process.
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