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Tunneling. Kinetic energy is used to overcome potential energy. More for motion past barrier Less creates turning point Objects with less energy should not cross high potential regions. E 1 < U 0 failure E 2 > U 0 success. Energy Barrier. x 1. x 2. E 2. U 0. E 1.
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Kinetic energy is used to overcome potential energy. More for motion past barrier Less creates turning point Objects with less energy should not cross high potential regions. E1 < U0 failure E2 > U0 success Energy Barrier x1 x2 E2 U0 E1
Wave duality permits particles to behave as waves. Waves can enter a barrier but lose intensity on entry. Exponential decrease Depends on energy U0-E Depends on barrier width w Reduced amplitude reflects the probability of barrier penetration. Quantum Wave U0 A0 Aw w
Optical microscopes are limited by light diffraction. About 500 nm Electron microscopes are also diffraction-limited. Debroglie wavelength About 0.2 nm Tunneling between a sharp tip and sample measures gap. Resolves 0.001 nm About 1% of atomic diameter Tunneling Probe
A scanning tunneling microscope (STM) uses a tunneling current to make images of atoms. STM 7 nm x 7 nm image: Cs atoms on GaAs (NIST) next
