Population analysis for atomic cascade decay processes

T. Kagawa, 薫 二葉

David A. Cardimona, M. P. Sharma, A. Gavrielides

The population dynamics of a four-level atom, with decay from the highest level, interacting with three arbitrarily intense laser fields is studied. In a previous paper [4], this four-level system was investigated with no decay included. For a specific set of input fields, it was found that substantial population could be transferred from the ground state to the highest excited state. In that study, the detunings required to obtain this maximum population transfer were not explained. In this present work, we have introduced a two-level atom model that explains this choice of detunings. They are such as to make the three fields resonant with the Stark-shifted

R. L. Fork, L. E. Hargrove, M. A. Pollack

Ivan A. Sellin, P. M. Griffin, John A. Biggerstaff

A more extensive analysis of the effects of different assumptions about initial state populations is added to a previous paper on the coherent excitation of hydrogen fine structure by foils. It is found that the previously postulated alignment of angular momenta perpendicular to the beam direction is a sufficient but not necessary assumption; an alternative assumption that the broad $l$-state distribution of the collision products has a maximum for $d$ states also matches the experimental traces adequately. A method of obtaining initial state populations in a manner which suppresses the corrections required for cascade effects is discussed. The method avoids the errors of extrapolating decay-curve fits.

David F. Zaretsky, S. B. Sazonov

L. J. Curtis

An analysis is presented of the instantaneous emission rate from an atomic level that is populated by arbitrary conditions of both collisional excitation and cascade repopulation. The general solution to the rate equations is obtained in terms of transition probabilities, excitation cross sections, and a simple integral operator, and applications are given for the specific examples of impulsive, stepwise, rectangular, gaussian, and modulated excitation conditions.