Low energy rescattering plateau in strong field photoemission from CNT-Au nanostructure

Abstract

A distinct low energy rescattering plateau at 1–2 eV is observed in strong field photoelectron emission from carbon nanotubes (CNTs)-Au composite nanostructures. In contrast, bulk Au exhibits a conventional high energy plateau, whereas pure CNTs generate only a narrow sub-eV direct electron peak without any visible plateau within the damage threshold. Electromagnetic simulations indicate that the Au coating increases the near field decay length around CNT tips, enabling rescattering pathways that are otherwise suppressed in pure CNTs. As the laser power increases, the low energy electron yield saturates, while the cutoff energy shows only a weak dependence on the driving field. This behavior is attributed to dynamic space charge accumulation, which modifies the effective optical field and introduces a net residual momentum, suppressing the conventional rescattering cutoff scaling. These findings reveal the combined roles of near field spatial confinement and dynamic space charge effects in shaping nanoscale strong field electron emission.