Angular distributions of single-photon and above-threshold detachment of sulfur hexafluoride anions in femtosecond laser fields

Abstract

We experimentally investigate the photodetachment of sulfur hexafluoride anions (SF6−) in 400 nm 35 fs laser fields using a home-built mass-selective anion source combined with electron velocity map imaging (VMI). The electron kinetic energy and the photoelectron angular distributions (PADs) are obtained from the VMI measurements. In addition to the single-photon detachment, two-photon above-threshold detachment (ATD), which is induced by strong laser fields with peak intensity higher than >1.0×1013W/cm2, is clearly identified for the first time. By fitting the measured PADs, the partial-wave distributions of the detached electron are achieved, resulting in the coefficiency of the s-orbital (p-orbital) of ∼68.1%(∼31.9%) in the mixed s–p molecular orbital of SF6−, which is in good agreement with the ab initio calculations. The ponderomotive shift in the ATD channel is investigated and different behaviors for the strong-field photodetachment comparing with that in weak laser fields are discussed. The present study adds to our knowledge on the photodeachment of the SF6− anion and sheds some light on the dynamics of the interaction of polyatomic molecular anions with ultrafast strong laser fields.