Ultra high vacuum with scanning tunneling microscope

In summary: But for the most part, you need to be a physicist with a good understanding of electronics and a good knowledge or TSM, or you will not be able to move atoms.
  • #1
baconbits423
18
0
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
 
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  • #2
baconbits423 said:
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:

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

Zz.
 
  • #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.
 
  • #4
baconbits423 said:
: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.

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.
 
  • #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.
 

1. What is an ultra high vacuum (UHV) in the context of a scanning tunneling microscope (STM)?

An ultra high vacuum is a specialized environment with extremely low pressure and minimal amounts of impurities. In the context of an STM, it is necessary to maintain a UHV in order to prevent any contamination or interference with the delicate measurements taken by the microscope.

2. What is the purpose of using an ultra high vacuum with an STM?

The purpose of using an UHV with an STM is to provide a clean and stable environment for the sample being studied. This allows for precise measurements and imaging without any interference from external factors such as air molecules or contaminants.

3. How is an ultra high vacuum achieved in an STM?

An UHV is achieved by using a combination of vacuum pumps and specialized chambers. First, a rough vacuum is created by using a rotary pump to remove the majority of air molecules. Then, a high vacuum is achieved using turbo molecular pumps that can reach pressures as low as 10^-9 millibar. Finally, an UHV is created using a cryopump or ion pump, which can reach pressures as low as 10^-12 millibar.

4. Can an ultra high vacuum be maintained indefinitely?

No, it is not possible to maintain an UHV indefinitely as there will always be small amounts of gas molecules present. However, with proper maintenance and regular pumping, an UHV can be maintained for extended periods of time.

5. What are the benefits of using an ultra high vacuum with an STM?

Using an UHV with an STM provides several benefits, including increased sensitivity and resolution, reduced contamination and interference, and the ability to study delicate samples without damaging them. It also allows for a wider range of experiments to be conducted, such as studying surface chemistry and atomic manipulation.

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