Week+of+3-25-2013

3-27-2013 I came in today and began scanning a mixed monolayer sample of Octanethiol and Adamantanethiol. The scope was acting very strangely and it. After several different attempts at approaching and changing the tip without it successfully tunneling, I tried to restart the computer and then I approached once more. After that did not work for about 1000 steps, I took the cover off and checked the tip and found that it was indeed crashed into the sample. I bumped the tip to move it away from that same area and approached. It worked in 346 steps. AB-1.22 µm, 2 A/D, 100 ms/line. I zoomed in to the upper middle of this image as it looked to contain some pretty interesting features. The next scan kept drifting out of range because of small jumps in the Z position that normally would not affect the scan at all. I checked it again and the electronics were displaying the Z position rather than the A/D output which is what I thought I was adjusting but I was actually adjusting the Z position which was what was causing problems with that scan. AC-2000 Å, 32 A/D, 100 ms/line. I zoomed into the upper right of this image. There was an incredibly high amount of drift in this image and throughout the entirety of the day. This was probably due to thermal drift as I had been looking at the wrong temperature readings the entire day and probably did not actually recognize that the temperature of the scope was not low enough to begin scanning.

AD-1000 Å, 128 A/D, 25 ms/line. I zoomed into the left middle of this image. AE-500 Å, 128 A/D, 25 ms/line. I scanned this and all of the following images using constant current mode. I zoomed into the middle of this image. AF-250 Å, 128 A/D, 25 ms/line. I moved the scanning region slightly to the left after this image. AG-250 Å, 128 A/D, 25 ms/line. I moved the scanning region up and to the right following this image. AH-250 Å, 128 A/D, 25 ms/line. After this image, I tried to move it slightly more to the right to avoid the structure on the left side. AI-250 Å, 128 A/D, 25 ms/line. At first, I thought that the 'structures' present in the images from AE to AI were indicative of a molecular structure on the surface. However, when I asked Matt about this, he informed me that these 'structures' were actually caused by high frequency noise in the scope and cannot actually be considered to be part of the molecular structure on the surface. I think this makes sense because the structure is not consistent throughout the entirety of the images and gives the illusion of a molecular structure in some spots while the streaks caused by it make it even blurrier in other spots