Field Ionization Thresholds of (17, n₁, n₂, 0) and (17, n₁, n₂, 1) Stark States of Sr Atom

The field ionization thresholds of n=17, |m|=0,1 Stark states of Sr atoms have been investigated by two-step excitation using ππ, πσ polarized lasers and both uniform and pulse electric fields. The results showed, contrary to the hydrogen 's, higher-energy states generally have lower ionization thresholds, and that the |m|=0,1 Sr atoms exhibit partly adiabatic behavior at several avoided crossings in the passage to ionization.