Carrier-Envelope Phase-Dependent Strong-Field Excitation.

We present a joint experimental-theoretical study on the effect of the carrier-envelope phase (CEP) of a few-cycle pulse on the atomic excitation process. We focus on the excitation rates of argon at intensities in the transition between the multiphoton and tunneling regimes. Through numerical simulations, we show that the resulting bound-state population is highly sensitive to both the intensity and the CEP.

Out-of-plane (e, 2e) experiments on helium L=0, 1, 2 autoionizing levels.

Out-of-plane (e, 2e) measurements are reported for the helium autoionizing levels (2s2)1S, (2p2)1D, (2s2p)1P, and for direct ionization. While the recoil peak almost vanishes in the angular distribution for direct ionization, it remains significant for the autoionizing levels and exhibits a characteristic shape for each orbital angular momentum L=0, 1, 2. A second-order model in the projectile-target interaction correctly reproduces the observed magnitudes of the recoil peaks, but is a factor of 2 too large in the central out-of-plane region.