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In the experiment of Purcell and Pound, the maximum magnetic field strength was 0.63Tand the initial temperature was 300K. Pretending that the lithium nuclei have only two possible spin states (in fact they have four), calculate the magnetization per particle, M/N, for this system. Take the constant μto be 5×10-8eV/T. To detect such a tiny magnetization, the experimenters used resonant absorption and emission of radio waves. Calculate the energy that a radio wave photon should have, in order to flip a single nucleus from one magnetic state to the other. What is the wavelength of such a photon?

Short Answer

Expert verified

The required values are:

MN=9.68×10−33JT−1E=1.008×10−26Jλ=19.7m

Step by step solution

01

Given Information

Magnetic field strength =B=0.63T

Temperature =T=300K

Constant related to the magnetic moment=μ=5×10-8eVT-1=8×10-27JT-1

02

Calculation

The magnetization per particle is given as:

MN=μtanhμBkT

By substituting the values in the above equation, we get,

MN=8×10−27×tanh8×10−27×0.631.38×10−23×300MN=(8×10−27)(1.21×10−6)MN=9.68×10−33JT−1

The magnitude of magnetism per molecule in this system is extremely low. As a result, the energy of a radio wave photon used to detect magnetization in the experimenters must be equivalent to the energy required to flip a single nucleus.

E=2μBE=2×8×10-27×0.63E=1.008×10-26J

The wavelength of such a photon is given as:

E=hcλλ=hcEλ=6.626×10-34×3×1081.008×10-26λ=19.7m

03

Final answer

The magnetization per particle is calculated as:

MN=9.68×10-33JT-1

To flip a nucleus from one magnetic field to another, the energy of the radio waves of the experimenter is calculated to be:

E=1.008×10-26J

For the photon to be in the radio wave region its wavelength is calculated to be:

λ=19.7m

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