Intense field double detachment of atomic versus molecular anions

The interaction of intense ultrafast laser pulses with atomic F- and with molecular SF6- anions is directly compared. The double-detachment mechanism is investigated by a systematic variation of peak intensity, polarization ellipticity, and pulse shape. For both systems, the observed weak polarization ellipticity dependence is not consistent with a rescattering-based mechanism. A double-detachment saturation intensity of 22±4×1013W/cm2 is determined for the atomic anion, which is significantly higher than the 9±2×1013W/cm2 of the analogous molecular system. The different atomic and molecular responses to spectral chirp and third-order dispersion induced pulse shapes are discussed in the context of the double-detachment time scale.