Mas aya del titular
La mision de este podcast es traer cada semana un nuevo caso y tema controversial que afectan en la comunidad Hispano. Las hostess de este podcast son Danyella y Denise.
Scanning tunneling microscopes (STMs) allow nanoscientists to see individual atoms.
July 24, 2017
To see how a Nanosurf easyScan STM works, let's take it apart in virtual reality.
The heart of the STM is an atomically sharp probe.
A voltage induces electrons to jump from the probe's tip to the sample atoms.
A feedback loop holds the electron current constant by keeping the distance from probe to sample constant.
But how can it move the probe over these tiny nanometer distances?
Voltages to a piezoelectric crystal move the probe in and out.
Another crystal moves it side to side.
A third crystal moves it up and down.
Let's see how these work together to create an atomic scale map of the sample surface.
The voltage to the back crystal determines pixel color. Voltages on the other crystals move the probe and pixels side-to-side and up-and-down.
But how do we first position the probe only a nanometer or so from the sample surface?
It's done by ratcheting this cylinder in until an electron current is sensed.
This STM is so simple that we use it in UVA classes. But it also earned two physicists the Nobel Prize in 1986.
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