Just wanted to ask a simple question to clarify my thinking. The Ionization Energy of an atom is said to be the minimum energy required to bring the electron to it's next higher orbit. Looking at the Oxygen atom's first ionization energy of 13.6eV. Does this mean that any energy level which is 13.6eV or higher will cause the first ionization to take place? Does this hold true for wavelength? A wavelength which is shorter than the absorbtion wavelength will also cause ionization because the shorter wavelength is stronger?