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## Main Question or Discussion Point

Hey there,

I'm pursuing a degree in Msc. Nanoscale science, and I've been studying about Scanning tunneling microsopes that use Quantum tunneling to study the surface struture of materials.

My question is: What is the maximum distance between the surface that's been studied, and the STM tip for which tunneling can occur?

I understand that the surface has to be quite close, of the order of angstroms or nanometers for the tunneling effects to start taking place, but if I apply a high enough voltage, can I achieve tunneling for a tip that is around a few centimeters to meters away?

What exactly are the parameters that determine tunneling? Is it just the distance? is the surface size of the tip? The voltage? A combination of all three? What are the maximum allowed values for these parameters? Are there any?

As far as I understand it, tunneling is just when electrons tunnel through a barrier, which is in the case of an STM, vaccuum. So, if the voltage is high enough, can the electrons tunnel in? I understand that the probability of tunneling undergoes exponential decay with distance. However, like I stated, if I had a high enough voltage, and if that's the case, how high should my voltage be?

I'm pursuing a degree in Msc. Nanoscale science, and I've been studying about Scanning tunneling microsopes that use Quantum tunneling to study the surface struture of materials.

My question is: What is the maximum distance between the surface that's been studied, and the STM tip for which tunneling can occur?

I understand that the surface has to be quite close, of the order of angstroms or nanometers for the tunneling effects to start taking place, but if I apply a high enough voltage, can I achieve tunneling for a tip that is around a few centimeters to meters away?

What exactly are the parameters that determine tunneling? Is it just the distance? is the surface size of the tip? The voltage? A combination of all three? What are the maximum allowed values for these parameters? Are there any?

As far as I understand it, tunneling is just when electrons tunnel through a barrier, which is in the case of an STM, vaccuum. So, if the voltage is high enough, can the electrons tunnel in? I understand that the probability of tunneling undergoes exponential decay with distance. However, like I stated, if I had a high enough voltage, and if that's the case, how high should my voltage be?

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