Electric-field–induced interferences in autoionizing resonances

Abstract

We have observed the effect of electric fields on the 5d9p ${}^3$ $P_1$° barium resonance above the first ionization threshold. This relatively broad autoionizing level is nearly degenerate with a much narrower level of opposite parity. At moderate fields the sharp level produces an interference dip in the broad level. At higher fields the interference eventually gives rise to two split components. The results are in good agreement with a nonperturbative theory, summarized in this letter.