Steven Chu, Claude Cohen-Tannoudji, and William Phillips received the 1997 Nobel Prize in Physics for “the development of methods to cool and trap atoms with laser light.” One part of their work was with a beam of atoms (mass ~ 10-25 kg) that move at a speed on the order of 1 km/s, similar to the speed of molecules in air at room temperature. An intense laser light beam tuned to a visible atomic transition (assume 500 nm) is directed straight into the atomic beam; that is, the atomic beam and the light beam are traveling in opposite directions. An atom in the ground state immediately absorbs a photon. Total system momentum is conserved in the absorption process. After a lifetime on the order of 10-8 s, the excited atom radiates by spontaneous emission. It has an equal probability of emitting a photon in any direction. Therefore, the average “recoil” of the atom is zero over many absorption and emission cycles. (a) Estimate the average deceleration of the atomic beam. (b) What is the order of magnitude of the distance over which the atoms in the beam are brought to a halt?

Question

Steven Chu, Claude Cohen-Tannoudji, and William Phillips received the 1997 Nobel Prize in Physics for “the development of methods to cool and trap atoms with laser light.” One part of their work was with a beam of atoms (mass ~ 10-25 kg) that move at a speed on the order of 1 km/s, similar to the speed of molecules in air at room temperature. An intense laser light beam tuned to a visible atomic transition (assume 500 nm) is directed straight into the atomic beam; that is, the atomic beam and the light beam are traveling in opposite directions. An atom in the ground state immediately absorbs a photon. Total system momentum is conserved in the absorption process. After a lifetime on the order of 10-8 s, the excited atom radiates by spontaneous emission. It has an equal probability of emitting a photon in any direction. Therefore, the average “recoil” of the atom is zero over many absorption and emission cycles. (a) Estimate the average deceleration of the atomic beam. (b) What is the order of magnitude of the distance over which the atoms in the beam are brought to a halt?

Expert Answer

Want to see the step-by-step answer?

Check out a sample Q&A here.

Want to see this answer and more?

Experts are waiting 24/7 to provide step-by-step solutions in as fast as 30 minutes!*

*Response times may vary by subject and question complexity. Median response time is 34 minutes for paid subscribers and may be longer for promotional offers.
Tagged in
Science
Physics

Physics of Atoms

Kinematics

Related Physics Q&A

Find answers to questions asked by students like you.

Q: Write the dimensions for at2 where a is acceleration and t is time.

A: The SI unit of the acceleration is meter/ sec2 and the dimension is [LT-2]. The SI unit of time is s...

Q: Calculate final temperature of 119 g of water heated with 1,840 J. The heat capacity of water is 419...

A: Given data The mass of the water is m = 119 kg. The heat supplied to water is Q = 1840 J. The specif...

Q: 13. ssm A highway is to be built between two towns, one of which lies 35.0 km south and 72.0 km west...

A: Click to see the answer

Q: atoms can occupy only certain discrete energy levels. Consider a gas at a temperature of 2 500 K who...

A: The ratio of the number atoms in the higher energy level to the lower energy level can be given as

Q: A block with mass of m¡ = 2 kg is placed on top of a block with a mass m2 = 4 kg. A horizontal force...

A: Click to see the answer

Q: For each of the following nuclei, determine the binding energy per nucleon (in MeV). (For all masses...

A: Click to see the answer

Q: Give an example of the product of inertia?

A: Click to see the answer

Q: Two transverse standing waves are shown in the drawing. The strings have the same tension and length...

A: Click to see the answer

Q: Assume the equation x = At3 + Bt describes the motion of a particular object, with x having the dime...

A: (a) In the given equation, x = At3 + Bt, x has the dimension of L and thus the dimensions of A and B...