CC BY 3.0 UnportedKübel, M.Arbeiter, M.Burger, C.Kling, Nora G.Pischke, T.Moshammer, R.Fennel, T.Kling, M.F.Bergues, B.2023-01-052023-01-052018-06-11https://oa.tib.eu/renate/handle/123456789/10768http://dx.doi.org/10.34657/9794We investigate the carrier-envelope phase (CEP) and intensity dependence of the longitudinal momentum distribution of photoelectrons resulting from above threshold ionization of argon by few-cycle laser pulses. The intensity of the pulses with a center wavelength of 750 nm is varied in a range between 0.7 × 1014 and . Our measurements reveal a prominent maximum in the CEP-dependent asymmetry at photoelectron energies of 2 U P (U P being the ponderomotive potential), that is persistent over the entire intensity range. Further local maxima are observed around 0.3 and 0.8 U P. The experimental results are in good agreement with theoretical results obtained by solving the three-dimensional time-dependent Schrödinger equation. We show that for few-cycle pulses, the amplitude of the CEP-dependent asymmetry provides a reliable measure for the peak intensity on target. Moreover, the measured asymmetry amplitude exhibits an intensity-dependent interference structure at low photoelectron energy, which could be used to benchmark model potentials for complex atoms.enghttps://creativecommons.org/licenses/by/3.0/530above threshold ionizationcarrier-envelope phasefew-cycle pulseslaser intensitystrong-field physicsArticle