Week+of+10-1-2012

10-1-12 I came in today and Matt was scanning. I changed the tip and began scanning a sample of C-60 on Gold. AJ-8135.71 Å, 4 A/D, 200 ms/line. I moved the scanning region to the left to try to avoid the large pits in the bottom middle. The blurriness of this image is more likely caused by the large pit that sits on the left side. I say this mainly because it turned out to be a fairly decent tip once I moved away from that region and began scanning smaller areas.Features are visible in this image, suggesting it is the surface causing the blurriness rather than the tip. AK-8135.71 Å, 4 A/D, 200 ms/line- I zoomed into a region in the upper middle of this scan to try and get a better image that was not blurred by huge pits and low resolution . Likewise in this image, the pits seem to be the cause of the blurriness as some faint features can be seen, specifically in the upper third of the image. The enormous Z-range that the tip has to travel causes the lack of definition. AL- 1000 Å, 16 A/D, 100 ms/line. The next three images, AM, AN, and AO, were all of the same region to check if the surface was decent enough quality for us to heat. The features in the images were similar enough that we decided the tip was of good enough quality for us to heat and try to find a change.

AM AN  AO There was a small amount of drift between these four images. Although there were small changes in the locations of the bright spots(most likely C-60 molecules), the structure of the image remained basically the same.

I heated up the gold after AO. I retracted the tip 15 steps then heated the gold for 5 seconds. I let it cool for a couple minutes thent it took 19 steps to approach. Then, it drifted for a few more minutes before I scanned.

I took a scan of the full area to look for the region from before.

AP-8135.09 Å, 4 A/D, 300 ms/line- It was definitely of the same region as before. I zoomed in to the part of the image where the region from AL-AO should have been. This image shows the derivative plot of this region. Unfortunately, for AK, I forgot to save its derivative plot, which looked exactly like this one. They were in almost the exact same position too; there was very little drift. It is still somewhat clear that the two regions are the same though, based on how the regions are in relation to one another. AQ-2000 Å, 32 A/D, 100 ms/line- I changed the A/D gain to 16 following this image and took a scan of the same region after adjusting for drift. This was an incredibly strange image. Neither Matt nor I knew what was causing this. The tip did not change too much from the before scans because the molecules on the surface are still fairly clear. AR-2000 Å, 16 A/D, 100 ms/line- I took another image of it to try to get a grasp on where the region from before could be. I ended up moving the scanning region to the right to look for it because I couldn't seem to find it here. AS-Same area as AR. These images are mostly the same. The molecules are still fairly clear on the surface as the bright spots. AT-2000 Å, 16 A/D, 100 ms/line. None of the features in this image resembled those from before. I moved the scanning region slightly to the left this time. The most interesting part of this image is probably the few craters that are present.They usually indicate that a mono-layer of Octanethiol is present, but are also usually a lot bigger. AU-2000 Å, 16 A/D, 100 ms/line. I made the scanning region smaller to 1500 Å following this image in order to scan the parts of it that are not the huge pit. Nothing can really be seen in this image because of the huge pit on the left side. Faint surface features are visible, which indicate that, perhaps the tip was not that bad. AV- 1500 Å, 32 A/D, 100 ms/line. I moved the scanning region up and to the right. There looked like there were some similar features between this image and AO. I also made the scanning region only 1000 Å. AW- 1000 Å, 32 A/D, 100 ms/line. I moved the scanning region to the left a slight bit because I could not find the region from earlier. AX- 1000 AÅ, 32 A/D, 100 ms/line. I moved the scanning region slightly more up and to the right to avoid the pit lining the left side. AY-1000 Å, 32 A/D, 100 ms/line. It did not appear to be similar to any of the regions from before the heating. I moved it fairly far left and somewhat down.

The bright streaks in images AV-AY are most likely the C-60 molecules. In many cases, they are present in a zig-zag fashion, which Matt claims is a consequence of the tip moving the molecules slightly as it moves across the surface, scanning it over a small distance. This is where we find the upper limit in our tip's quality. The tip has been able to show the molecules, but it is clearly fiddling with the surface as it scans, lowering its reliability. AZ- 1000 Å, 32 A/D, 100 ms/line. There was a huge pit in this image lining the right side. I moved it to the left to avoid this. BA- 1000 Å, 32 A/D, 100 ms/line. It didn't really resemble anything from earlier. These last two images seem blurrier than those preceding it from a different region. This is possibly caused by the pit lining the right side in both images.However, the same tip quality looks to have remained. There also looks to be some more junk on this surface.However, my main goal was looking for the region from earlier. It didn't look like I was going to be able to find this region as my many attempts have been unsuccessful and it was near the time to leave. I decided to call it a day instead of trying to look for the region from earlier or changing the tip.

10-2-12 I came in today and began working with Matt. Matt had heated the sample slightly before I came in and we waited several more minutes for it to cool. The tip took 19 steps to approach. I let the tip drift for a couple more minutes. The Z-offset was almost as far in the negative direction as it possibly could be. It would not drift back to a scannable level so I retracted the tip 4 steps, adjusted the Z-offset back to 0, and then approached. The Z-offset normalized and I was able to begin scanning.

10-2-12AB

10-2-12AF 10-2-12AG 10-2-12AJ 10-2-12AK Between the set of previous images, there is definitely a decrease in the amount of C-60 molecules on the surface. These images were not taken by me. I am merely using them as a pretense to the results that came later on this day. AL- 4 A/D, 8134.78 Å, 400 ms/line. Following this image, I moved the X and Y offsets left and up respectively to find the region from earlier. The next scan included the region from before that Matt had been studying. I changed the scan size to 2000 Å and the A/D gain to 32 and scanned this region. AM- 2000 Å, 32 A/D, 400 ms/line. I stopped the scan almost halfway through and moved it slightly to the left to get a more similar region to the images from earlier. AN- 2000 Å, 32 A/D, 100 ms/line. I did not let this scan finish either. I moved the scanning region up a bit to avoid the pits in the bottom third of the previous image. Also, the quality of this image indicates that there was likely a tip change. AO- 2000 Å, 32 A/D, 100 ms/line. I decided that, despite the decrease in tip quality, I was going to heat the sample. I retracted the tip 15 steps then heated it for 7 seconds. It took 19 steps to approach afterwards. I took a full scan to look for the general region. The C-60 molecules are the seen here as the small bright spots around the image. There seem to be less of these spots than on the previous image of this region, "AK". A very important part of this is that the gold does not seem to move as the gold structure that lines the right side has remained in the same relative spot throughout the different heatings. AP- 8135.40 Å, 4 A/D, 400 ms/line. This was only a half image because I could partially see the region I wanted and instead of waiting for the scan to finish, I moved the X-offset to the right and the Y-offset a little bit up. AQ- 8135.40 Å, 4 A/D, 400 ms/line. I zoomed in to the region in the previous images following this one. AS- 2000 Å, 32 A/D, 200 ms/line. It was not a very good image. I think there was a tip change near the end which caused the quality to decrease immensely. I moved the scanning region up and to the left to try to avoid this. This image, because of the lowest region, has an extreme amount of blurriness. The tip drifted and quite possibly changed near the end. The C-60 molecules are present in this image but are very faint. That is why I decided to take the image again. AT- 2000 Å, 32 A/D, 200 ms/line. I once more moved the scanning region up to try to avoid the bottom region.

AU- 2000 Å, 32 A/D, 200 ms/line. There were some pretty interesting things on this surface. Matt suggested that I scan with a different bias. I changed the bias from .3 V to .15 V. AV- 2000 Å, 32 A/D, 200 ms/line. It was of the same area as before, just up and to the right. I adjusted for this movements and scanned the region again. AW- 2000 Å, 32 A/D, 200 ms/line. After this image, I scanned the same region with a -.15 V bias to see how the features from before would change. AX-2000 Å, 32 A/D, 200 ms/line. It did not look too different from the previous images. The previous four images chronicle a deterioration of the tip. They also show a decrease in the amount of Octanethiol molecules on the surface. This may suggest that the C-60 molecules are evaporating. However, beginning in AT, one can start seeing the first appearance of light regions forming around the craters in the gold. This may also be caused by the C-60 molecules or they could be reacting with the surface, when heated, in a way we have never seen before.