Above-Threshold Ionization, Energy-Resolved Photoelectron Angular Distributions, And Momentum Distributions Of H-2+ In Intense Femtosecond Laser Pulses

We study above threshold ionization, energy-resolved photoelectron angular distributions and photoelectron momentum distributions for the initial (2)Sigma(+)(g)(1s sigma(g)) ground and the (2)Sigma(+)(u)(2p sigma(u)) first-excited state in H-2+, driven by an arbitrary orientated linearly polarized 800 nm laser pulse of different intensities and temporal durations. When the pulse duration is reduced, multiphoton structure is erased, and continuum states of gerade (g) and ungerade (u) inversion symmetry start to overlap. A strong localization of the photoelectron emission occurs as a consequence of the g-u mixing. Furthermore, as the pulse length is reduced, effects of the carrier-envelope phase show up, and a number of complicated interference patterns in the momentum distribution radially as well angularly are predicted. Such patterns were previously reported in the atomic case. In the molecules, additional structures appear due to the interference between electronic waves emerging from different nuclear centers.