Interferences in photoelectron spectra - Holographic structures

LÓPEZ, S. D.; ARBÓ, D. G.

Barcelona

Conferencia; 26th International Conference on Atomic Physics, ICAP 2018; 2018

When an intense short laser pulse interacts with anatom ionizing it, the photoelectron spectra presentseveral structures that can be understood as doubleslit interferences in the time domain, namely intraandinter-cycle interferences [1]. This type of structuresare formed by electrons that emerge from theatom and follows directly to detector. There is anothertype of structures that requires interference offormer direct electrons with other that interact withthe parent core. In a classical picture, the latter returnsto the parent ion driven by the laser eld andrescatters o to the detector. It is well known that ashort range potential is sucient to understand therescattering rings at high energy, formed by very hardinteraction among electron and ion [2]. Other structurescan be explained only when long range coulombicinteractions take place. This type of structurescan be interpreted as holograms, i.e. the interferencepattern between the direct (reference) and therescattered (signal beam) electrons. In this way, theinformation of the interaction is encoded in the interferencepattern between the reference and the signal[3].In this work we present a theoretical analysis of interferencesusing a numerical solution of the time dependentSchrodinger equation (TDSE) and semiclassicalapproaches, namely, quantum trajectory montecarlo (QTMC) and the semiclassical two step model(SCTS) [4]. We analyze the ionization of atomic hydrogento characterize the role that the long rangeCoulomb interaction plays in the holographic stuctures.Particularly, we focus our analysis for very fewcycle laser pulses allowing ionization in some parts, toturn on and o dierent kind of interferences. Withsemiclassical approaches we can examinate the trajectoriesthat lead to dierent nal conditions andget a deeper understanding of the electron kinematicsassociated to holographic structures.In addition, by using short-range potentials asYukawa potentials, we studied the eects of theCoulomb tail, and the screening parameter on theholographic structures. This allows us to interpretthe electronic distribution as the dispersion of an electronwavepacket that crosses the region of interaction,and to establish relations with the shape of the potential.We show in Figure 1 photoelectron distributions asfunction of parallel kz and perpendicular kx momentumto polarization axis calculated with SCTS model(upper pannel) and the TDSE (lower pannel). All theFigure 1: Photoelectron momentum distribution for ion-ization of atomic hydrogen by a short laser pulse offrequency !=0.0575 a.u. and electric eld amplitudeF0=0.05 a.u. calculated within the SCTS model for a sin-gle period laser pulse for SCTS (upper gure) and TDSE(lower gure).magnitudes are in atomic units. We observe interferencepatterns resembling a dispersion of an electronwave packet from a potential centered in the originin both calculations.This work was supported by the by CONICET(PIP100386) and ANPCYT (PICT-2016-0296 andPICT-2016-3029).[1] Arbo, D. G., Ishikawa, K. L., Schiessl, K., Persson,E., and Burgdorfer, J. Phys. Rev. A 81, 81,021403 (2010)[2] Lewenstein, M., Kulander, K. C., Schafer, K. J.,and Bucksbaum, P. H., Phys. Rev. A 51, 1495,(1995)[3] Huismans, Y., Rouzee, A., Gijsbertsen, A., etal., Science,331, 61 (2011)[4] Shvetsov-Shilovski, N. et al., Phys. Rev. A, 94,013415 (2016)341