We review multipulse interferometric frequency-resolved optical gating (MI-
FROG) as a technique, uniquely suited for pump-probe coherent spectroscopy
using amplified visible and near-infrared short-pulse systems and/or emissi
ve targets, for time-resolving ultrafast phase shifts and intensity changes
. Application of polarization-gate MI-FROG to the study of ultrafast ioniza
tion in gases is presented.