Low-energy interference structure with attosecond temporal resolution

Accessing precisely to the phase variation of electronic wave-packet (EWP) provides unprecedented spatiotemporal information microworld. A radial interference pattern at near-zero energy has been widely observed in experiments strong-field photoionization. However, underlying physical picture this is still under debate. Here we report an experimental and theoretical investigation low-energy structure (LEIS) mid-infrared laser fields. We clarify that LEIS arises due soft-recollision mechanism, which was previously found play a pivotal role producing pronounced structure. Specifically, induced by between direct EWPs launched within 1/18 laser-cycle time scale our experiments. Moreover, observation independent wavelength specific atomic targets. Our result opens promising new avenue for retrieving dynamics atoms molecules with attosecond resolution.