Week+of+10-5+and+10-6

10-5-11 I came in today at about 4 P.M. and began scanning a sample of Octanethiol on Au(111) that Natalie had prepared for me. After unsuccessfully scanning and changing the tip twice, I was finally able to get a good scan. This was "AA". "AA" was a general scan of the area to search for a smaller area with a large amount of features. "AA" showed a very large number of features, both valleys and hills. This image had a lot of potential for future zoomed in imaging. For the next image, "AB", I zoomed in to the top middle region of "AA". "AB" was much noisier than "AA" it seemed. However, I decided to shoot the laser at "AB" to see what would happen with the valleys and the hill on top. I brought the power of the piezoelectric stack from 45.0 V to 5.0 V. I then shot the laser for one minute and let it cool for five minutes. After cooling I brought the power back up to 45.0 and began scanning again. "AC" was a terrible image and it was probably not a very wise decision to shoot the laser at "AB" because it had an extremely low quality and bad tip. After "AC", I changed the tip. "AD" was a great image. It was a general scan looking for smaller regions with high amounts of features. The tip for this image was pretty good and the images following. "AD" had a lot of potential. I zoomed into the middle part of "AD" for "AE". I brought the power of the piezo electric box from 45.0 V to 5.0 V. I shot the laser at "AE" for one minute and let it cool for five minutes. I brought the voltage back up to 45.0 V and took an image which was "AF". I zoomed in to the middle of the area on the left side for "AG". I then brought the voltage from 45.0 V to 5.0 V and shot the laser for one minute. I let the sample cool for five minutes and brought the power back up to 45.0 V and began scanning again. Both "AG" and "AH" were good images. After I changed the tip after scanning "AC", all of my images improved in quality but there was still a little lack of definition due to noise but the better tip helped a lot. Today was one of the most important days so far in my research. It further showed how much letting the sample cool for a longer time than heating it really improved the after image. Typically, when I let the sample cool for the same amount of time that I heated, it does not scan when I increase the voltage of the piezo stack to its original voltage. Every time I shot the laser today and let it cool for a substantially longer time then I heated it, I was able to raise the voltage to its original amount and scan the sample in basically the same area.

10-5-11AA media type="custom" key="10747228" 10-5-11AB 1st Laser Attempt Before: media type="custom" key="10747234" 10-5-11AC After: media type="custom" key="10747242" 10-5-11AD media type="custom" key="10747250" This image showed an extremely large amount of features. It was a very good image and had great future potential. There were a large of amount of hills and valleys, which is unusual because there are usually only valleys and a couple of hills. The new tip helped improve the quality of this image substantially but there is still noise here as seen by the slight blurriness throughout. 10-5-11AE 2nd Laser Attempt Before: media type="custom" key="10855060" width="140" height="140" align="right" media type="custom" key="10747254" "AE" was the zoomed in region of the middle of the top half of the previous image. There was also a high amount of definition on this image as seen by the quality of the features but it was still difficult to see the Octanethiol on the surface because of the noise. 10-5-11AF After: media type="custom" key="10747264" Unfortunately, the scanning region moved down and to the left. You can clearly see the features that correspond between the two images. The largest hill and second from the top of the after image (excluding the half of the hill scanned in the left upper side), fifth from the top in the before image, is wider and seems to be more stretched in the after image. The valley below that in the after image decreased in size and also seems to have become longer. The small valley right above the largest hill in the second image was longer vertically in the first image and is longer horizontally in the after image. The first hill from the top (again excluding the half hill in the upper left corner) has become smaller and more circular in the after image compared to its counterpart in the before image. Also the hill in the bottom left corner of the before image seems to have decreased in size in the after image and also become more circular but we cannot know for sure because we cannot see the entirety of it in the first image. 10-5-11AG 3rd Laser Attempt Before: media type="custom" key="10747272" This was the zoomed in region of the the left upper part of the previous image, "AF". This image had a good amount of defined features and showed a very good tip. There was still some noise though as one can see with the blurriness in this image and the streaks that cover the majority of the image. This makes it difficult to see any of the Octanethiol on the surface. 10-5-11AH After: media type="custom" key="10747276" This image showed only a very small move in the scanning region. The large valley in the middle of the right side of the after image seemed to have decreased greatly in size and scrunched vertically from the before image to the after image.The hill above this valley and slightly to the right became more circular and it seems to have become smaller between the two images but we cannot know for sure because we do not have the full hill covered in the scan. The hill directly to the left of the large main valley stretched horizontally From the two successful laser attempts today, and with the available information I can utilize in the scans, I have hypothesized that after the gold(with the unobserved Octanethiol) is heated and enters an excited state and it is cooling, the gold will even out more in terms of topography, increasing the evenness of the surface as seen with the decrease in size of many of the features. When an area on an image is black or white it indicates a striking difference in topography; in today's scans, the majority of pitch black and bright white areas decreased from the before to the after image.

10-6-11 I got in to the lab today at 3:50 and began scanning the same sample of Octanethiol on Au(111) from yesterday. I took three scans and changed the tip after "AC" because these scans were not good at all. After changing the tip, I scanned "AD" and this image was not very good. However, I zoomed in to the middle of the top part of the top left quarter and scanned this region, This was "AE". "AE" had a very large amount of features but they were not very defined so i tried to zoom in even more and see what I would get. I zoomed in to the majority of the middle right side of "AE". This was "AF". This image showed a decrease in quality. I hoped that if I moved the area to the right I would be able to get something better. I was unfortunately incorrect and the image quality decreased so I changed the tip. I was able to only get one more image for the rest of the day and this image was quite bad. Today was not a very good day in the lab mostly due to poor quality of tips. That, along with noise, created an unfriendly environment for scanning. 10-6-11AA media type="custom" key="10794102" This was the first image of the day and it was not very good.It showed a lot of noise and a bad tip, especially on the left side. There was a lot of noise throughout the whole image and little definition. Some features were faint on the right half but none of them was very clear. 10-6-11AB media type="custom" key="10794114" I zoomed into the right upper half of the previous image for this image. This image showed a high amount of noise and very little definition. The features were clearer in this image than in the previous one but since it was still such a wide scanning range I tried to zoom in once more. 10-6-11AC media type="custom" key="10794118" This was the bottom right corner of the previous image.It started alright but ended terribly. There was an extremely large amount of noise on the image and the streaks across the image show show that there is a bad tip. After this terrible display, I decided to change the tip. 10-6-11AD media type="custom" key="10794120" This image showed both a bad tip and a considerable amount of noise. There were a lot of features but the poorly cut tip diminished their quality. 10-6-11AE media type="custom" key="10794128" There was a good amount of features on this image but there was not enough definition to shoot the laser at this image. This was due most likely to the bad tip and noise.

10-6-11AG media type="custom" key="10794138" This image showed even less definition than the previous image but many more features. Unfortunately, due to the low definition caused by the bad tip and noise, it would not have been worth firing the laser. I changed the tip after this image. 10-6-11AH media type="custom" key="10794144" AH showed a very large amount of features, mostly valleys. The image shows a lot of streaks, caused by both noise and a bad tip. It's quite possible that, if zoomed in, this image could have shown some smaller more promising areas. However, at the end of the image, the sample retracted slightly for some unknown reason, either me or someone else accidentally hitting the table and it moving, or the STM could have malfunctioned. Overall the images for this day were not very good due mainly to bad tips. Noise played a role in the poor quality but it was not as detrimental as the low quality of the tips.