THE EFFECT OF LASER-PULSE WIDTH ON THE MULTIPHOTON IONIZATION EFFICIENCY

We studied the variation of the multi-photon ionization efficiencies o f atoms as a function of the laser pulse width under the condition of constant pulse energy. The density-matrix calculation showed that long pulses were preferred for efficient ionization whenever the lifetimes of the levels involved in the transition were longer than the pulse w idths. Also, it was demonstrated that the atomic and the laser paramet ers, such as transition cross-sections, laser pulse widths, and lifeti mes affect the optimal excitation rate of the transition for efficient multi-photon ionization.