An X-ray photon collides with a free electron and the photon’s wavelength is observed to increase by 0.0050nm. Which statement about the scattering angle θ of the photon is most strongly supported by this observation? (The Compton wavelength of the electron is 2.43×10−12m.)
a) The photon must have been scattered at essentially 180∘ because the measured wavelength increase equals the theoretical maximum.
b) Such a wavelength increase is impossible for a free-electron collision because it exceeds the theoretical maximum shift.
c) The photon was scattered at exactly 90∘ because that angle gives the largest possible wavelength change.
d) The photon was most likely scattered at about 40∘, the angle that corresponds to the calculated shift.