EFFECTS OF A LASER-PULSE PHOTOIONIZING AN EFFECTIVELY EXCITED 3-LEVELATOM ON THE ION YIELD

The population inversion in a three-level atomic system, interacting w ith two coherent laser pulses, occurs from the first level to the thir d level at the optimal detunings of the laser frequencies near the two -photon resonance. An examination is performed to see whether the ener gy density and time-delay of the photoionizing laser can significantly influence the ion yield for the case where the atom interacts with tw o coherent pulses and one photoionizing pulse incoherently coupled. Th e well-known three-colour, three-step, three-photon ionization scheme, which is available for the selective photoionization of Yb-168, is ch osen for use in this research with the Bloch equation. It is revealed that the proper time-delay and energy density enable us to achieve hig her efficiency for the selective photoionization of Yb-168, regardless of the Doppler-broadening, though the efficiency and selectivity of c oherent excitation are prominently enhanced by applying the optimal de tunings.