Above-threshold ionization of argon with ultrashort orbital-angular-momentum beams

Abstract

Light-matter interaction with laser pulses endowed with orbital angular momentum (OAM) raises a fundamental question about the nature of the transfer of this property of light to matter. In this work, a “reaction microscope” is used for precise measurement of the momentum of ionized photoions and photoelectrons from the interaction of Ar atoms with a linearly polarized, ultrashort (∼25 fs), moderately intense (1013–1014W/cm2) OAM carrying laser pulses. The angle and energy-resolved photoelectron spectrum is compared with the photoelectron spectrum obtained from the interaction with the laser beams with no OAM at similar intensities. No evidence of angular momentum transfer to the electrons from light is observed in our experiment.