Week+of+1-11+and+1-12

1-11-12 I came in today and began scanning a sample of Octanethiol on Au(111) that Natalie prepared. I will be scanning with 70 V charged on the piezoelectric stack and see what kind of results I will be able to get with the laser. The first tip gave no results so I switched it and began scanning again. The same thing happened with the second tip. Because of this, I decided to change the voltage amount and bring it down to 50.0 V to see if this had been negatively affecting the sample. I tried scanning once more and it did not work. I cleaned the sample holder and the landing of the STM with Ethanol. After letting this dry for about three or four minutes, I began scanning again. I was able to get an image on my first try. I think that the higher voltage was somehow negatively affecting the scanning process and preventing the STM from scanning. It is also possible that this had no adverse affect and it was only the dirty sample holder/landing that was preventing it from scanning. This scan that I got was going well until I changed the samples from 128 to 256. Then, the STM freaked out and bottomed out. I stopped the scan, backed the sample up, then reapproached it. It successfully scanned this time. This image, "AA", was fairly decent. I zoomed in to the bottom left quadrant. "AB", the next image, was also pretty good and I wanted to shoot the laser at it but I decided against it because I wanted to know more deeply the quality of the tip and see if I was able to get atomic resolution. I zoomed in to the middle region and going slightly to the bottom right of this image. This image was not very good and it showed no atomic resolution. I changed the tip afterwards. Following this, I was unable to scan any more decent images despite several changed tips and cleanings of the sample holder and landing. 1-11-12AA media type="custom" key="12077413" This image's upper half showed no real insights to the surface and had such large differences in elevation that allowed for nothing to be seen. The features in the bottom left quadrant and the bottom right quadrant held the possibility of showing well-defined features and the possibility of seeing Octanethiol. As shown below, I zoomed in to the bottom left extending off the image. I chose this region over the one in the bottom right because it looked noisier and the one on the left looked undefined only because of the scanning parameters. 1-11-12AB media type="custom" key="12077427" "AB" had pretty well-defined features but seemed like a pretty noisy image. There were no hills in this specific scan but it seemed possible that the cascading lines in the image could have been Octanethiol molecules. I zoomed in to the middle region of this image and found that these lines were simply noise, debunking my hypothesis. Transition media type="custom" key="12077521" 1-12-12 I came in today and began scanning the same sample of Octanethiol on Au(111) from yesterday that Natalie prepared. I scanned with 50.0 Volts charged to the piezoelectric stack. The first image, "AA", was fairly blurry so I cut the tip. The next image, "AB", was better but had a lot of problems with elevation differences on the right side. I zoomed in to the bottom left quadrant. This zoomed in region, "AC", was quite blurry and noisy so I changed the tip afterwards. The next image, "AD", was decent but because of its scanning parameters I was unable to know if this was caused by a bad tip or simply the parameters I was using. I zoomed in to the region in the bottom left quadrant. This region was very blurry-- I stopped it about halfway through and changed the tip. After several failed attempts, I was finally able to get the STM to scan and not crash like it had the several times before. "AE" had many feautres, both valleys and hills. I zoomed in to a region in the bottom left quadrant. This next scan was incredibly blurry and the features in the previous image were now wrought with noise and were very ill-defined. I stopped the scan about 40% of the way through and did not have enough time afterwards to complete any more scans. 1-12-12AA media type="custom" key="12088463" This image had a lot of noise and showed clearly that there was a bad tip involved. There were several features in the bottom right quadrant and the top right quadrant but it was evident from the scan that I would not have been able to gain any insight into the surface of the gold because of the blurriness. 1-12-12AB media type="custom" key="12088467" About half of the area in this image is completely incomprehensible due to drastic differences in the elevation of the surface. However, the parts that we can see show a large amount of features. I zoomed in to the bottom left quadrant of this image to try to get a better grasp of the surface. 1-12-12AC media type="custom" key="12088483" This image showed a horrible tip, as evidenced by the streaks that run rampant throughout the entirety of the image. It was clear from this image that I needed to change the tip. 1-12-12AD media type="custom" key="12088499" This image shows quite a bit of features but a lack of definition. After zooming in to the the middle 50% of the left side, I affirmed that the tip on this image was poor and changed it subsequently. 1-12-12AE media type="custom" key="12088509" This image seemed to be the most promising of all from today. There were plenty of features and it looked to be a pretty clear and defined picture in the bottom half of the image. However, when I zoomed in to the bottom left quadrant, I found that there was incredibly high amount of noise, indicating a poorly cut tip. I tried messing with the parameters to increase the quality of the scan but nothing worked. I stopped the scan about 40% of the way through.