Experimental Investigation of Topological Property of Degenerate Singularities in Rescattering Processes

Abstract

AbstractWe measure rescattering photoelectron momentum distributions (PEMDs) of randomly oriented CO$${ }_2$$ 2 molecules by a carrier-envelope phase (CEP)-stable few-cycle pulse. A cutoff structure of measured PEMDs agrees quantitatively with the Airy function-like universal distribution calculated by the adiabatic theory. This behavior is guaranteed by the singularity theory, and originates from the topological property of a caustic, which is singularity of action described by the Hamiltonian formulation. We experimentally reveal the topological properties underlying the caustic in the rescattering processes.