The effect laser pulse width on the multi-photon ionization efficiency

We studied the variation of the multi-photon ionization efficiencies of 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 widths. Also, it was demonstrated that the atomic and the laser parameters, such as transition cross-sections, laser pulse widths, and lifetimes affect the optimal excitation rate of the transition for efficient multi-photon ionization