Intracycle interferences in 2D-momentum distribution of atomic photoionization

D. G. ARBÓ; K. L. ISHIKAWA; E. PERSSON; J. BURGDÖRFER

Belgrado

Conferencia; 5th Conference on elementary Processes in Atomic Systems; 2011

Interference effects observed in the electron yield of atomic ionization due to the interaction with linearly polarized high intensity laser pulses are studied [1]. The interplay between intra- and intercycle interferences of electron trajectories leads to modulations in the photoelectron doubly-differential momentum distributions. Intercycle interference corresponds to the well-known ATI peaks of the photoelectron spectrum arising from the superposition of wave packets of different optical cycles, whereas intracycle interference comes from the coherent superposition of electron wave packets released within the same optical cycle. The latter corresponds to a diffraction grating in the time domain [1,2].  In Fig. 1 we display the two-dimensional momentum distribution calculated by numerically solving the time-dependent Schrödinger equation (lower figure) and by using a calculation based on the Simple Man’s Model (upper figure). The intercycle interference pattern can be seen as concentric rings, which are modulated by the intracycle interference observed as oblique stripes. The intracycle interference modulation is independent of the total number of optical cycles involved in the laser pulse and is affected by the long-range nature of the atomic potential.