Appearing and disappearing strong-field (2d+time) resonances in H atoms - art. no. 060101

When excited hydrogen atoms are driven by collinear static and microwave el ectric fields, we discover a series of strong-field resonances that can ion ize most substates with a given principal quantum number n(0). We describe a quantal theory using an adiabatic basis that explains the origin of the r esonances and why they disappear at certain ratios of the two fields. Our t hree-dimensional classical Monte Carlo calculations reproduce this behavior . We demonstrate n selectivity sufficient for continued development of this process as a practical detector.