Scientists have discovered that electrons cooled close to absolute zero slow down so much that they can be studied individually – allowing us to see the world in a whole new level of detail.
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CrazyNeutrino said:
Scientists have discovered that electrons cooled close to absolute zero slow down so much that they can be studied individually – allowing us to see the world in a whole new level of detail.
More…
ChrispenEvan said:
CrazyNeutrino said:
Scientists have discovered that electrons cooled close to absolute zero slow down so much that they can be studied individually – allowing us to see the world in a whole new level of detail.
More…
I’ve never heard of scanning tunnelling spectroscopy done at 15 milliKelvin before. ;-/
I see. “Lowering the temperature to maximise the spectroscopic resolution” is a good strategy, but produces the problem that noise from individual electrons becomes very significant.
“Superconducting tips have successfully been conducted to circumvent the broadening effects of the Fermi function in the tunnelling process and greatly improve the energy resolution. However, at low temperature, other energy scales such as the charging energy of the tunnel junction may substantially exceed the thermal energy such that the granularity of the tunnelling current becomes non-negligible.”
I see, so it isn’t low intensity that produces this problem, it’s the low temperature itself.
“The question arises whether the tunnelling process encompasses an intrinsic resolution limit which cannot be overcome.” The answer is Yes. “In our case leading to ΔE in the low μeV-range”. The resolution limit “is dominated by the capacitative noise and is essentially determined by the junction capacitance as well as the temperature.” The smaller the capacitance, the worse the resolution.
The good news is that even at fixed capacitance, the resolution still increases linearly with the negative logarithm of the temperature. So to get any desired resolution you can just keep cooling the sample.