Attosecond strobing of two-surface population dynamics in dissociating H2+

Using H-2(+) and D-2(+), we observe two-surface population dynamics by me(+) (D-2(+)) ionize in short (40-140 fs) and intense (10(14) W/cm(2)) infrared laser pulses. Experimentally, we find a modulation of the kinetic energy spectrum of the correlated fragments. The spectral progression arises from a hitherto unexpected spatial modulation on the excited state population, revealed by Coulomb explosion. By solving the two-level time-dependent Schrodinger equation, we show that an interference between the net-two-photon and the one-photon transition creates localized electrons which subsequently ionize.