## Abstract

In this paper we analyze two-photon-resonant three-photon ionization of atomic oxygen via the 2p3(4S°)np3P0,1,2, and the 2p3(4S°)nf 3F2,3,4 states. The various atomic parameters required for calculating the resonant enhanced multiphoton ionization (REMPI) probabilities are obtained using quantum-defect theory. The infinite sums over nonresonant states are truncated at a finite number of terms. Our calculated two-photon excitation cross sections agree well with the results of other recent calculations and of experimental measurements. The photoionization cross section is calculated for various electron kinetic energies. The REMPI dynamics is analyzed by solving the density-matrix equations. This framework consistently takes into account the effects of saturation and ac Stark shifts. REMPI probability is seen to be quite sensitive to the initial detuning, the intensity, and the particular resonant state accessed. The photoionization cross sections also imply that due to the rapid falloff of the cross section, two-color REMPI schemes with a lower-frequency ionizing photon would increase the effective REMPI probability.

Original language | English (US) |
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Pages (from-to) | 4220-4228 |

Number of pages | 9 |

Journal | Physical Review A |

Volume | 37 |

Issue number | 11 |

DOIs | |

State | Published - 1988 |

Externally published | Yes |

## ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics