Angular distribution of ejected electrons from autoionizing 3<i>pns</i>states of magnesium

Abstract

We have measured the angular distribution of electrons ejected from doubly excited autoionizing Rydberg 3pns J=1 states of magnesium, where n=10--20. Two dye lasers cross an atomic beam and excite 3${\mathit{sns}}^{1}$${\mathit{S}}_{0}$ states of Mg. A third linearly polarized laser excites the 3pns states. The angular distribution is of the form (\ensuremath{\sigma}/4\ensuremath{\pi})[1+\ensuremath{\beta}${\mathit{P}}_{2}$(cos\ensuremath{\theta})]. We measure \ensuremath{\beta} as a function of the energy of the third laser. The \ensuremath{\beta} parameter varies over its full range of values, -1 to 2. Our data agree quite well with the predictions of the reaction-matrix--multichannel-quantum-defect theory.