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Scanning Tunneling Microscope - How Nanoscientists see Atoms

Por: John C. Bean - WeCanFigureThisOut.org

16 episodios disponibles

Latest episodes of the podcast Scanning Tunneling Microscope - How Nanoscientists see Atoms

Scanning tunneling microscopes (STMs) allow nanoscientists to see individual atoms. 24/07/2017

To see how a Nanosurf easyScan STM works, let's take it apart in virtual reality. 24/07/2017

The heart of the STM is an atomically sharp probe. 24/07/2017

A voltage induces electrons to jump from the probe's tip to the sample atoms. 24/07/2017

A feedback loop holds the electron current constant by keeping the distance from probe to sample constant. 24/07/2017

But how can it move the probe over these tiny nanometer distances? 24/07/2017

Voltages to a piezoelectric crystal move the probe in and out. 24/07/2017

Another crystal moves it side to side. 24/07/2017

A third crystal moves it up and down. 24/07/2017

Let's see how these work together to create an atomic scale map of the sample surface. 24/07/2017

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. 24/07/2017

But how do we first position the probe only a nanometer or so from the sample surface? 24/07/2017

It's done by ratcheting this cylinder in until an electron current is sensed. 24/07/2017

This STM is so simple that we use it in UVA classes. But it also earned two physicists the Nobel Prize in 1986. 24/07/2017

This podcast is drawn from the Virtual Lab presentations of WeCanFigureThisOut.org. The copyrighted material of this site was developed under funding from National Science Foundation CCLI, NIRT, MRSEC and NUE programs. This project is led by John C. Bean

All of the scenes together