Week+of+10-29-2012

10-29-2012 I came in to the lab today and took the gold sample off the heating block where it was in Octanethiol solution for 15 hours. I then began scanning. The goal is to get better images of the Octanethiol heating experiment to support the paper that we submitted if it were to come back from the publisher saying that we need more evidence. The scanning settings were off as the line time was set to be 0 seconds, Also the colors on the image line window, which displays the topography of the sample in relation to some arbitrary zero point, were not what they usually were. I tried scanning and everything seemed to work fine. AA-7181.20 Å, 300 ms/line, 4 A/D. I zoomed in to the region in the upper right corner of this image. AB-2000 Å, 200 ms/line, 32 A/D. I decided to take a second image of this region just in case it were to calm down and I could get a better picture of it. In this image, there are somewhat unclear outlines of what appear to be domain boundaries of Octanethiol molecules around gold atoms on this surface. However, because of the noise seen here, a clear picture of them cannot be obtained. AC-2000 Å, 200 ms/line, 32 A/D. I moved the scanning region to the left a little bit to avoid the extreme lows in the bottom right. AD-2000 Å, 200 ms/line, 32 A/D. While scanning this image, Matt came in and told me what the noise in the image was being caused by and told me to hit the range button then turned the isolation tables on. I scanned again and it looked even worse. This image more accurately displays the boundaries between the lighter gold atoms and the lines of Octanethiol molecules that separate them. This is especially prevalent in the upper left quadrant. AE-2000 Å, 200 ms/line, 32 A/D. I stopped it and scanned into the flat region on the left side of the image. It was not very good and I decided to take a full image after this to try and look for a better region to zoom in to. This image is a step down in quality from those before. This is because the isolation tables were turned on and the box was messed with in between this and the previous scan which most likely caused movement in the tip to a worse area on the surface. AF-7187.18 Å, 200 ms/line, 4 A/D. I found the region from earlier fairly quickly and zoomed in to it. This image here is quite strange. It looks as if there is a double tip involved that I had not noticed earlier. The features on the left block and on the large right terrace repeat in a way that doesn't seem like it could be explained outside of a double tip. AG-2000 Å, 200 ms/line. 32 A/D. I decided to try to scan this image again but with a higher A/D gain. AH- 2000 Å, 64 A/D, 200 ms/line. I zoomed in to the upper left corner in order to get a better image of the surface. AI- 1000 Å, 128 A/D, 150 ms/line. I decided to heat the gold after this image. I retracted the tip 15 steps then heated the gold for 5 seconds. I let it sit for 5 minutes and then it approached in 19 steps. This image, of all of the ones from today, most accurately displays the relationship between the Octanethiol molecules and the gold atoms on the surface. The molecules create boundaries around the gold atoms and form into something like what we see here. This surface is full of junk however which causes a sharp decrease in its quality and its actual applicability. AJ-7179.93 Å, 4 A/D. None of the areas in this image resembled closely what I was looking for from the past images. It was reaching the time that I had to leave and it didn't look like it was remotely close to anything I needed so I called it a day.

10-30-2012 I came in today and changed the tip as soon as I could as the undergrad who had been scanning tried one last time to scan before leaving and had a horrible tip. I then began scanning a sample of Octanethiol on Au(111). AH-7193.93 Å, 200 ms/line, 4 A/D. I zoomed in to the region in the bottom right that looked to contain some very interesting features. AI- 2000 Å, 200 ms/line, 32 A/D. I moved the scanning region slightly up to avoid the decrease in elevation in the lower left. This and the following image show the domain boundaries of the Octanethiol molecules and how they form on the surface. They mostly form in straight lines around gold atoms on the surface that they bond around. Their formation and their changes because of heat are of great interest. AJ- 2000 Å, 200 ms/line, 32 A/D.I zoomed in to the upper left region so as to acquire better resolution. AK- 1000 Å, 100 ms/line, 128 A/D. This image clearly showed domain boundaries on the surface, indicating that there was indeed a monolayer on the surface. This image more vividly details the qualities of an Octanethiol monolayer than possibly any image I have ever had before. Unfortunately it is incredibly noisy and full of streaks. The domain boundaries are shown here as the darker borders that extend out from the small holes in the gold surface. If I remember correctly, these small holes in the surface are caused by the Octanethiol molecules pulling gold atoms off of the surface and bonding to them. However, because of the low quality of this image, we are not able to look at the individual atoms involved as the resolution is not very high. There was quite a bit of low frequency noise which obscured our vision of this surface. I retracted the tip then found that the wires that connect the resistor to the power supply were resting on top of the wires that connect the piezoelectric tube to the electronics of the scope. I fixed that problem then re-approached. An even stranger noise appeared and I suggested to Matt that the piezo had been wobbling when I was placing the tip and he checked and found that the piezoelectric tube was not secured tightly by the screw that is supposed to hold it. He tightened it and then I resumed scanning.

AL-7193.93 Å, 300 ms/line, 4 A/D. I zoomed in to a region in the upper left quadrant that looked fairly flat and quite interesting as it was full of small craters. I tried to get an image but just kept finding myself in huge craters. I took another huge image and about halfway through I found the region I needed. Shortly there-after, I stopped the scan and zoomed in to that region. AM-7193.93 Å, 300 ms/line, 4 A/D.The region of interest is along the lower left side of the image. I tried zooming in but again, I could not get the region I wanted. I took another big image. AN-7193.93 Å, 200 ms/line, 4 A/D. As soon as I found my desired region I stopped the scan and zoomed in. This time it was successful. AO-2000 Å, 200 ms/line, 32 A/D. I moved the scanning region slightly to the right and up to avoid the pits along the left side. AP-2000 Å, 200 ms/line, 32 A/D. Distinct boundaries which form around clusters of gold atoms are not present in this image, making it a fairly useless image to heat as no real atomic or molecular changes could be observed. I also assume that much of this low quality was probably caused by the large put lining the left side of the page. I had attempted multiple times to solve this by moving it but the scope stayed in basically the same spot every time I tried moving it.