April+'09

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The past week, April 20 - 24, Annette was in Utah for a conference, so I was not able to go into lab to do research.

The previous week, I got to work with the new laser, a 75 mW green laser. I used the more powerful laser and implemented it into the same setup where I used a 4 mW laser. As with the 4 mW laser, a hole (0.5 cm diameter) was drilled into the back of the laser so that the wires could be pulled through. I redid all the wiring and soldered laser into the circuit so that the switch could continue to be used outside of the STM box. It seems that using the sample holder associated with this experimentation (the one with a conical hole in the back to allow laser access) has significantly greater problems adjusting to the STM environment. There is always a lot of drift when experimentation initially starts. The sample holder is made of a different material which may contribute to this. The conical hole may also heavily affect the stability of the sample. This problem may be solved simply by keeping the sample holder in the STM box, even when not being used for experimentation, to allow it to adjust. If the weight is a factor, washers at the bottom of the stabilizer can be removed to compensate for the heavier sample holder.

The week before that, April 6 - 10, I was able to go in and scan while using the laser, but heavy drifting caused by the problems mentioned above prevented any effective imaging.