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Ultra high vacuum with scanning tunneling microscope

  1. Mar 14, 2007 #1
    I am working on a project involving a scanning tunneling microscope, and to move atoms i need an untra high vacuum chamber. Any info you have on UHV or STM would be immensly appreciated.:rolleyes:




    Thanks
     
  2. jcsd
  3. Mar 14, 2007 #2

    ZapperZ

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    What kind of information do you need? As in what type of pumps and gauges to use?

    Zz.
     
  4. Mar 14, 2007 #3
    :rolleyes: Any thing, mostly about a uhv, for example does it need to be at a certain temp, what types of pumps are needed, what is necessary to use a scanning tunneling microscope to lift atoms off of a surface.
     
  5. Mar 14, 2007 #4

    ZapperZ

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    It has nothing to do with the uses. If you need UHV, then the technique is similar no matter what it is used for.

    I gather that you don't have any other persons around that can help you with this? Usually, in many cases, people learn from existing systems, or from people who have either assembled or maintained such a system. So asking something like this from ground zero is rather unusual.

    You definitely need (i) an oiless roughing pump (ii) a turbo pump and (iii) either an ion pump or a cryopump. The roughing pump will serve 2 purposes: (i) to get you to approximately 10^-5 Torr and then you can start the turbo pump and (ii) to back your turbo pump. Once you get to low 10^-7, then you can start the ion/cryopump.

    You will also need one regular vacuum gauge and an ion gauge that can go to 10^-12 torr.

    The most tedious part is designing where such pumps should go. You want to minimize the use of vacuum lines because this will only reduce the conductance and lower your pumping efficiency. You will also need to learn "UHV hygene". Cleaning the parts that go into the system is essential (one usually clean them with citrinox solution in an ultrasound bath, and then acetone+ethanol rinse), and vacuum-approved gloves and wiping cloth and aluminum foil are also required.

    Again, it is difficult to describe the process on here if you want to have a complete picture. I strongly suggest you find someone who has done this, and who has a good "vacuum" technique.

    Zz.
     
  6. Mar 16, 2007 #5
    You cannot build an UHV device if you do not have experienced people besides you to guide and help you. You cannot build it for less than several thousand dollars (or tens of thousands).
    For the TSM the situation is very similar. If you are an experienced physicist with a good knowledge in electronics and a good funding you can (may be) built it in a year. To be able to move atoms, you can add a few more years.
     
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