IAFE   05512
INSTITUTO DE ASTRONOMIA Y FISICA DEL ESPACIO
Unidad Ejecutora - UE
artículos
Título:
Nonconstant ponderomotive energy in above-threshold ionization by intense short laser pulses
Autor/es:
R. DELLA PICCA; S. LOPEZ; C. R. GARIBOTTI; A. A GRAMAJO; S. D. ARBÓ
Revista:
PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 2016 vol. 93 p. 234191 - 234198
ISSN:
1050-2947
Resumen:
We analyze the contribution of the quiver kinetic energy acquired by an electron in an oscillating electricfield of a short laser pulse to the energy balance in atomic ionization processes. Due to the time dependenceof this additional kinetic energy, a temporal average is assumed to preserve a stationary energy conservationrule, which is used to predict the position of the energy peaks observed in the photoelectron (PE) spectra. For aplane wave and a flattop pulse, the mean value of the quiver energy over the whole pulse leads to the concept ofponderomotive energy Up. However, for a short pulse with a fast changing intensity, the stationary approximationloses its validity. We check these concepts by studying first the PE spectrum within the semiclassical model(SCM) for multiple-step pulses. The SCM offers the possibility to establish a connection between emission timesand the PE spectrum in the energy domain.We show that PE substructures stem from ionization at different timesmapping the pulse envelope. We also analyze the PE spectrum for a realistic sine-squared envelope within theCoulomb-Volkov and ab initio calculations solving the time-dependent Schr¨odinger equation. We found that theelectron emission amplitudes produced at different times interfere with each other producing, in this way, a newadditional pattern that modulates the above-threshold ionization (ATI) peaks