Problem #0016 Quantum Physics Problem #0018 Chapters Chapters


Problem 49.46 (RHK)

To remove an inner, most tightly bound, electron from an atom of molybdenum requires energy of 20 keV. If this is to be done by allowing a photon to strike the atom, we have to find (a) the associate wavelength of the photon; (b) identify the region of the electromagnetic spectrum in which the photon lies; (c) and answer whether this process could be called a photoelectric effect.

Solution:             Click For PDF Version


Wavelength corresponding to a photon that has energy of 20 keV required for making free the most tightly bound electron from a molybdenum atom can be found from the relation


As the wavelength of the photon required for removing the most tightly bound electron of a molybdenum atom is of the order of pm, it lies in the x-ray region of the electromagnetic spectrum.


In photoelectric effect a free electron is emitted from a metal surface by absorbing energy from a photon, the recoil momentum is shared by the lattice to which electron is weakly linked. On the other hand when a tightly bound electron is emitted from an atom, the recoil momentum is taken by the ionised atom.