Laser photoionization spectroscopy is based on the resonance ionization of atoms and molecules as a result of successive absorption of several laser photons. Photoionization cross sections have number of utilities in the applied areas of science and technology such as space and astrophysics, radiation protections, laser designing and interaction of electromagnetic radiation with matter. The atoms whose ionization potentials are much higher can be ionized by two-photon and multi-step excitation. The absolute photoionization cross sections of the excited states of lithium, sodium and potassium...