Angle-dependent molecular above-threshold ionization with ultrashort intense linearly and circularly polarized laser pulses

We present molecular above-threshold ionization (MATI) spectra generated by ultrashort intense linearly and circularly polarized laser pulses from nonperturbative numerical solutions of the corresponding time-dependent Schrodinger equation in the molecular-ion H-2(+). It is found that high-order MATI spectra with maximum kinetic energy 32U(p), where U-p = I-0/4m(e)omega(2)(0) is the ponderomotive energy at intensity I-0 and frequency omega(0), can be obtained in H-2(+) at great internuclear distances R for both linear and circular polarizations. Quasiclassical laser-induced collision models confirm that such high-order MATIs mainly result from a collision with neighboring ions of the ionized electron. Interference patterns in the high-order MATI spectra are critically sensitive to both the internuclear distance R of the molecules and the polarizations of the driving laser pulses. Moreover, with few-cycle laser pulses, the carrier-envelope phase sensitivity of MATI angular distributions is also investigated for varying internuclear distances R. At critical internuclear distances for charge-resonance-enhanced ionization, we also find that enhanced interference patterns occur.