# Necessary photon energy for electronic excitation

What happens if a photon incident on an atom has greater energy than the difference of energies between successive energy levels corresponding to electronic excitation(say between ground state and next energy level) but smaller for multi energy-level hop? Will the photon be absorbed or not?

• The photon energy will typically span some nonzero bandwidth $$\Delta\omega$$, which is limited by the Heisenberg Uncertainty Principle (HUP) to be no smaller than $$2\pi/T$$, for $$T$$ the total duration of the experiment.