Week+of+5-16+and+5-17

5-16-12 I came in today and began scanning a sample of Octanethiol on Au(111) that Natalie prepared. Before I took any scans, I cleaned the sample holder and landing with Ethanol. The first scanning attempt was very blurry. I changed the tip after adjusting the parameters several times without success. The first scan had many features and looked quite promising. I tried zooming in but the program would not let me so I restarted it and tried to scan the same area as before, which became "AB". I zoomed in to a region in the lower left of "AB" and its result was absolutely horrible. There was an incredibly high amount of streaks and it seemed like there was no definition at all. I stopped it and cut the tip. The next three attempts ended in the STM scanning with a crashed tip. I restarted the STM. It worked and scanned correctly but it was very blurry so I had to cut the tip. The same thing happened twice more where I would get working, terrible scans that required me to cut the tip to change it. This behavior continued for the rest of the day.I was unable to get anything even close to of value for the second half of the day. 5-16-12AA media type="custom" key="18214866" 5-16-12AB media type="custom" key="18214992" It is fairly clear that I was able to take a picture of the same region I had before the program malfunctioned. I was actually fairly surprised that when I zoomed in, I got a low quality image. There are plenty of features and they seem relatively well-defined. There does not seem to be overwhelming evidence that the tip is dull. Perhaps the best indicator of this could be the boundary between the terrace in the upper middle and the region running down the left side. I had zoomed into the bottom left quadrant and encountered pure noise. The entire scan was just streaks and the features were all of horrible quality. Their boundaries were ill-defined and the valleys were covered with noise. 5-17-12 I came in today and began scanning the sample of Octanethiol on Au(111) from yesterday. The STM continued its habit from yesterday of crashing the tip when it approached. I restarted it in hopes that it would work better and, just as yesterday, it scanned correctly. However, the scan was incredibly blurry so I had to change the tip. My first image after this, "AA", had some valleys and a few hills. It was ill-defined and covered in streaks. I cut the tip after it. The STM worked without crashing this time. However, the next two scans were both of low quality; I cut the tip promptly. "AB" had many features but was less blurry than "AA" and previous scanning attempts. I decided to shoot the laser at it. I felt like it could possibly improve the sharpness of the tip. I shot the laser for 35 seconds and let it cool for 60 seconds. "AC" was of the same general region, just moved down and to the right. I wanted to see what would happen if I shot the laser at it again so I shot it for 30 seconds at "AC".I let it cool for 60 seconds and took another scan. It was also of the same area. I changed the tip after it because the tip quality had not improved really and the image was still blurry. The next scan looked promising for it had many hills and valleys. However, as I adjusted the scanning parameters to try to get a clearer picture, I found that the tip was actually very dull and the image became horribly blurry. I stopped about one-third of the way through it. 5-17-12 media type="custom" key="18361258" There are few hills in this image. There are, however, many valleys. There are also a great number of streaks.The region with a high concentration of valleys on the right side is fairly dirty looking. That type of surface structure is a fairly good indicator of a low quality tip. 5-17-12AA-AB-AC media type="custom" key="18361264" The areas present in the white and black regions are the only clear assemblies of Octanethiol molecules that are evident in all three images. Either the tip quality improved and I could see more of the clump in the black region in contrast to the surface or the molecules reformed over a larger area than before after being heated. This appeared to happen to the two hills in the white region from "AB" to "AC". The hills in this region then look more round in "AD" than in "AC". The tip quality looks to have improved from "AB" to "AC" but decreased from "AC" to "AD". This is based on the fact that there is a smaller amount of haze covering the features in "AC" than in "AD" and "AB". There is also a more definitive barrier between the features and the surface.