Strong field driven extreme nonlinear photoemission from individual single-walled carbon nanotubes

Photoemission from nanostructures under strong fields has attracted significant interests in materials science and optoelectronic applications. Here, we report the extreme nonlinear photoemission in single-walled carbon nanotubes (SWCNTs) and its underlying mechanisms related to the microscopic carrier excitation and the sequential emission of occupied-state electrons. We show that the characteristic photoemission responses, e.g., nonlinear slope, of individual SWCNTs strongly depend on the unique electronic structures near the Fermi level, i.e., localization of the emitting states and their tunneling probabilities. The transition of photoemission mechanisms giving rise to the extreme nonlinear behavior was elucidated using Kohn-Sham potentials and the extended Fowler-Nordheim theory. This paper provides insights into photoemission dynamics of SWCNTs on the ultimate atomic length scale and attosecond time scale, will hopefully help design materials for tunable optoelectronic responses.