This makes detailed predictions difficult. In the latter case, however, would only be for . This indicates that the EM field would have no driving effect at all even on a free electron. First, when electrons are expelled out of focus there is practically no ponderomotive force for acceleration. The atoms or ions are truly probed by the rapidly oscillating and perhaps spiking strong EM field.
Stabilization is a nonperturbative and nonlinear effect.
For example, at high frequencies in the nonrelativistic regime. This behavior could be compensated by increasing I, leaving finite in contrast to nonperturbative predictions. It is possible to obtain an estimate of I for minimum at . Using various sources of information it should be of the order of for the hydrogen atom but much less for a loosely bound electron. The first attempt to observe stabilization would simply mean ion yield measurements as a function of I at fixed .