Above Threshold ionization of Argon Atoms by multicolor XUV radiation

DELLA PICCA, RENATA; LINDROTH, EVA

Bariloche

Conferencia; 17 international conference physics of highly charged ions; 2014

Division Colisiones Atomicas CAB

In a recent experiment the energy-resolved photoelectron (PE) spectra produced via two-extreme-ultraviolet-(XUV)-photon above-threshold ionization (ATI) of argon were observed [1]. The XUV radiation consisted of higher-order harmonics (11th to 16th) of the original laser ω0 (λ = 800 nm) generated by the process of the relativistic oscillating mirror in high-peak-power laser-pulse interaction with solid targets.In the present work we analyze theoretically the argon PE spectra, using experimental light-pulse parameters. Due to the high frequency of the XUV radiation, the Coulomb- Volkov approximation should be adequate [2]. Below we show the results in very good agreement with the experimental spectra [1]. As explained in [1], the ten peaks withenergies ranging from 22 to 32 ω0 (right panel) correspond to absorption of two photons, each contributing 11−16 ω0 , where different combinations lead to the same excess energy, thus contributing to the same ATI peak. We observe a variation in the relative intensityof the peaks depending on the description of the target and the first ionization step.