Week+of+9-24-2012

9-24-12 I came in today and scanned C-60 on Gold. It was much less dense than the previous samples because it had been dissolved in Benzene. Matt told me that he got some pretty decent images earlier today: "AB" and "AK". Between these two images, there appeared many small holes inside of the C-60 molecules that were not there before the heating that Matt performed before I arrived. AB AK 9-24-12AP- 8135.40 Å, 4 A/D, 250 ms/line. I zoomed in to the region in the upper left quadrant that was flattest. I changed the A/D gain from 4 to 32 and scanned. This derivative plot shows the many clusters of C-60 molecules. The junk-like stuff on top of the surface and between the two steps in the left middle and in the lower left corner are probably a result of a crashed tip from earlier or something else that landed on the surface. I zoomed in to the highest step in the upper left quadrant. 9-24-12AQ- 2000.00 Å, 32 A/D, 200 ms/line. It drifted near the end so I moved the scanning region up to avoid the pit in this image. The molecules are fairly clear in this image. The relatively large brighter regions show the molecules.However, their structure is fairly unclear because of the quality of the tip and the pit in the lower right that lowered the overall quality of the image. 9-24-12AR- 2000.00 Å, 32 A/D, 200 ms/line. I retracted the tip manually by 15 steps then heated the gold for 5 seconds. I let it cool for a couple minutes then approached again. This time it took 19 steps to approach. I let it drift for a minute before scanning then took a full image. This image was slightly better than the previous two. There were still streaks in it though. The brighter regions should be the clusters of C-60 molecules. WE wanted to see how these would change so we tried heating them. 9-24-12AS- 8135.09 Å, 4 A/D, 250 ms/line. This was definitely in the same general region as before, just down and to the left. I adjusted the X and Y offsets up and to the right then scanned. The definite characteristics that this image shares with "AP" are the junk molecules and the way in which the two steps diverge from each other in the upper right quadrant. This image is of similar quality to "AP" and shows the molecules throughout the surface. The next two images are simply me trying to accurately pinpoint the region from "AR". 9-24-12AT-8135.09 Å, 4 A/D, 250 ms/line. I went too far up in relation to the region in "AP". I moved the scanning region down and scanned another full image. 9-24-12AU-8135.09 Å, 4 A/D, 250 ms/line. I zoomed in to the region where the region from AR should be. 9-24-12AV-2000.09 Å, 32 A/D, 200 ms/line. I tried moving it to the left to avoid the region along the right side. This scan seems to have many more streaks than those before the heating. It seems noisier and less defined. The region in the upper right could have been causing this general haze as well as the large pit in the lower middle. It is hard to tell if much has changed from "AR" to this image. 9-24-12AW-2000.09 Å, 32 A/D, 200 ms/line, I moved the scanning region down and to the left then adjusted the slight drift. This image also does not reveal much change or distinct difference between this and the before image. It is also of lesser quality, perhaps caused by the heating ruining the surface. 9-24-12AX-2000 Å, 32 A/D. I moved it to the bottom right quadrant of the scanning region to see what I could get after this image. This is another image of the same region, just moved over slightly to the left. This eliminated the region in the upper right yet the quality of the image remained about the same.

9-24-12AY-2000 Å, 32 A/D. This was the last scan for the day. This image was of a completely different region, thousands of Angstroms from the previous images. The quality of this image is mostly consistent with the previous few images, suggesting that it is the quality of the tip that has deteriorated over the course of scanning. The pit in the upper third also caused that area of the scan to have an even lower level of quality. There are many streaks here and the molecules are fuzzy. Not much can be gained from this image about the surface molecules. 9-25-12 I came in today and began scanning a new sample of C-60 on Au(111) that Matt prepared for today. When I arrived, I found that the undergrad Chris had been scanning and left the STM tunneling when left, perhaps because he knew I was coming shortly after. I checked out some of his data and concluded that I needed to change the tip before scanning. 9-25-12AP- 2000 Å, 16 A/D, 200 ms/line. This image was fairly blurry. I moved the scanning region up following it. The streaks in this image are most obvious along the left side and along the pit on the right side of the image. It is incredibly blurry. The surface seems to be flooded with C-60 molecules, though they are very poorly defined and not much can be gained from them. 9-25-12AQ- 2000 Å, 16 A/D, 200 ms/line. I moved the scanning region to the left and changed the A/D to 32. This image is not any better than the previous one. It actually is a bit blurrier.There are streaks throughout it and C-60 molecules can be seen fairly obviously but they cannot be studied in great detail because of this tip's quality. 9-25-12AR- 2000 Å, 32 A/D, 200 ms/line. There was some drift near the end. I moved the scanning region slightly over to the left to try and avoid the pit running down the right side. The C-60 molecules are somewhat more clear in this image than the previous two. They are not as numerous though. However, there is still not a high enough level of detail for these to be studied accurately. The tip drifted and was not the sharpest. Streaks can most clearly seen on the left side of the image. 9-25-12AS- 2000 Å, 32 A/D, 200 ms/line. I changed the tip following this image. It was quite blurry and had drifted as far as possible in the negative Z direction, making me unable to adjust the drift anymore. This image had horrible drift. I couldn't finish it despite the multiple times I tried. I eventually just saved the partial image and changed the tip to try to get a better image. Unfortunately, I was not able to obtain anything besides collections of streaks following the tip change. More importantly, Matt ran some calculations and found that the solution of C-60 that he was using to coat the surface of the gold contained enough C-60 to create 10 monolayers when we only want one. We will definitely take a different approach to the making of the solution or use multiple to dilutions to gain this desired amount.