Week+of+3-14+and+3-15

3-14-12 I came in today and began scanning a sample of Octanethiol on Au(111) that Natalie prepared. The first scan was very poor so I changed the tip. This happened with the next two scans. "AA" was my first finished scan and it was fairly blurry. However, it looked as if there could have been Octanethiol on the bottom half of the image. I zoomed in here. After reducing the I and P gains, I was left with a general haze. I changed the tip part of the way through. After that, the STM would not approach. I restarted the STM and cleaned the sample holder and apparatus. It approached after I did this. "AB" was a fairly decent image. It looked fairly blurry but had good features. I zoomed in to the eight hills in the middle. "AC", the next image, had streaks throughout and did not look very well-defined. Hopefully tomorrow will turn out better than today I will be able to have more consistency in the sharpness of my tips. 3-14-12AA media type="custom" key="13268682" This is a very fuzzy image. The features in this image are also not very well-defined. There does not appear to be any Octanethiol on the surface. 3-14-12AB media type="custom" key="13268606" The streaks in this image somewhat resemble what Octanethiol chains would look like. However, it appears that these streaks are simply a result of noise. This is shown pretty clearly by the poorly defined boundaries. 3-1412AC media type="custom" key="13268600" This image has streaks that are quite similar to those of the previous image, suggesting that they are more likely simply noise rather than Octanethiol molecules. The boundaries of the features are not very well-defined and there is a decent amount of noise here as shown by the hill in the top middle. 3-15-12 I came in today and saudered the wire connecting the Piezoelectric stack to its power supply box. Then I scanned with the same sample of Octanethiol on Au(111) from yesterday. The STM was not connecting to the computer after I tried restarting it because of my approaching failures. I unscrewed the wires and screwed them in again. I restarted the computer and the STM successfully connected. I resumed scanning. However, the STM still wouldnot scan. I tried scanning with graphite and it worked. I stopped it, changed the tip, and resumed scanning the gold. The first scan came shortly after at 4:40 pm. This scan was still horrible though. I decided I would finish it just because of how the STM was acting. I changed the tip afterwards. The next scan was quite poor. I stopped it about halfway through and cut the tip. The next scan I took was actually pretty decent. It had a lot of mounds that were decently defined. However, during the scan, the STM bottomed out. I quickly reapproached, adjusted the scanning range, and moved the scanning region. I was able to scan a region of similar quality to the first one. This image was fairly decent and there were clear features under the general brightness caused by the vast difference in elevation. I zoomed in to the middle of "AC". The zoomed in scan was horribly poor and noisy. I changed the tip midway through. "AD" was fairly interesting because of its hills and the streaks that painted the entire image. I decided to shoot the laser at it. I brought the voltage of the Piezoelectric stack down from 40.0 V to 5.0 V. Then I shot the laser for 40 seconds and let it cool for 2 minutes. When I brought the voltage back up to 40.0 V, the sample crashed and when I tried withdrawing and approaching, I scanned an entirely different and blurrier region. 3-15-12AA media type="custom" key="13268618" This image is horribly blurry. There is no real definition or features visible here. The streaks in the top right show very clearly how horrible the tip was from my multiple crashes in my attempts to make the STM scan. 3-15-12AB media type="custom" key="13268620" Although the drastic differences in elevation do not really allow us to see this image clearly, we can see the features underneath the brightness caused by the discrepancies. This is most evident in the bottom left quadrant. The bottom right and upper right suggest that the tip is poor because of their lack of definition. I zoomed in to the bottom left quadrant.

3-15-12AC media type="custom" key="13268628" The features in this image are decently well-defined. The streaks here resemble slightly what Octanethiol should look like but it is fairly clear from the noise in the bottom half that these streaks are simply caused by the tip rather than the actual molecules. 3-15-12AD media type="custom" key="13268630" The boundaries of the hills in this image are not very well defined. It is tough to tell whether there are Octanethiol molecules but I think it is safe to say that the streaks here are just caused by noise.