Obtain the de Broglie wavelength of a neutron of kinetic energy 150 eV. As you have seen in Exercise 11.31, an electron beam of this energy is suitable for crystal diffraction experiments. Would a neutron beam of the same energy be equally suitable? Explain.
(mn = 1.675 × 10–27 kg)
Given:
Kinetic energy of neutron, E = 150 eV = 150 × 1.6 × 10-19
E = 2.4 × 10-17 J
Mass of neutron, mn = 1.675 × 10-27 Kg
Kinetic energy of a particle is given by,
We can write,
mv = (2 × m × KE)0.5
P = (2 × m × KE)0.5 ...(1)
Where,
m = mass of electron
v = velocity of electron
p = momentum of particle
By putting the equation (1) in de- Broglie equation, we get,
…(2)
Now substituting the values in eq (2) we get,
λ = 2.327 × 10-12m
A neutron cannot be used in diffraction experiment as lattice spaces are of the order of few 10-10 m, whereas the wavelength of a neutron beam is 100 times smaller.