Laser Assisted Photoionization of Argon Atoms

A. A.GRAMAJO; R. DELLA PICCA; LÓPEZ, S. D.; ARBÓ, D. G.

Paris

Simposio; The 5th International Symposium on Intense Short Wavelenght Processes in Atoms and Molecules ISWAMP; 2019

ABSTRACTThe laser-assisted XUV photoelectric effect (LAPE) occurs when extreme ultraviolet(XUV) and infrared (IR) lasers overlap in space and time. In this case, the photoelectronspectrum is factored into two contributions: one that accounts for the intracycle (during oneIR cycle time interval) electron emission and the second one describing the intercycleinterference (due to the emission at different IR cycles) [1,2,3]. This intercycle interference isthe responsible of the well-know ?sidebands? (Sbs) in the photoelectron spectrum separatedat energy values given byEn = nωL + ωX - Ip - Upwhere ωX(L) is the frecuency of XUV(IR) pulse, Ip is the ionization energy, Up theponderomotive energy and n is the number of absorbed or emitted IR photons.In the present work we consider the Argon photoionization from the subshells 3s, 3p0 and3p1 due to a short XUV pulse assisted by an IR laser both linearly polarized. Within thecontinuum-distorted wave Strong Field Approximation (SFA) supported by the ab initiosolution of the time-dependent Schrödinger equation (TDSE) we study the angle-resolvedmomentum distribution of photoelectron for the case that both fields are linearly polarized.We analyze and characterize the modulation of both factors, the intra- and intercyclecontributions, on the spectrum.In particular, we study several geometrical arrangements between the polarization vectorsand the emission direction, that give rise to selective photoelectron sideband energies in thethe ionization spectrum, as in the case of perpendicular emission where only odd sidebandsare observed.During the conference we will theoretically analyze the selection rules that governs theallowed photoelectron energies, showing that the intra-half-cycle factor [1,3] destructivelyinterfere to cancel some sidebands peaks.REFERENCES1. A. A. Gramajo et al, J. Phys. B: At. Mol. Opt. Phys. 51, 055603 (2018).2. A. A. Gramajo et al, Phys. Rev. A 94, 053404 (2016).M. P. Brown and K. Austin, Appl. Phys. Letters 85, 2503-2504 (2004).3. A. A. Gramajo et al, Phys. Rev. A 96, 023414 (2017).