Chapter 40: Q. 12 (page 1175)
A helium atom is in a finite potential well. The atom鈥檚 energy isbelow . What is the atom鈥檚 penetration distance into the classically forbidden region?
Short Answer
The penetration depth is
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Chapter 40: Q. 12 (page 1175)
A helium atom is in a finite potential well. The atom鈥檚 energy isbelow . What is the atom鈥檚 penetration distance into the classically forbidden region?
The penetration depth is
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The correspondence principle says that the average behavior of a quantum system should begin to look like the Newtonian solution in the limit that the quantum number becomes very large. What is meant by 鈥渢he average behavior鈥 of a quantum system?
An electron approaches a wide potential-energy barrier of height . What energy electron has a tunneling probability of (a) 10%, (b) 1.0%, and (c) 0.10%?
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Tennis balls traveling faster than routinely bounce off tennis rackets. At some sufficiently high speed, however, the ball will break through the strings and keep going. The racket is a potential-energy barrier whose height is the energy of the slowest string-breaking ball. Suppose that atennis ball traveling at is just sufficient to break the -thick strings. Estimate the probability that a ball will tunnel through the strings without breaking them. Give your answer as a power of rather than a power of.
a. What is the probability that an electron will tunnel through aair gap from a metal to a STM probe if the work function is ?
b. The probe passes over an atom that is鈥渢all.鈥 By what factor does the tunneling current increase?
c. If a current change is reliably detectable, what is the smallest height change the STM can detect?
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