Laser phase control of high-order harmonic generation at large internuclear distance:: The H+-H2+ system

Exact (Born-Oppenheimer) 3-D numerical solutions of the time-dependent Schrodinger equation are obtained for the one electron linear H+-H-2(+) atom-molecule system at large internuclear distance R in interaction with two-cycles intense (I > 10(14) W cm(-2)) 800 nm laser pulses. High-order harmonic generation (HHG) spectra are obtained with an energy cutoff larger than the atomic maximum of I-p+3U(p), where I-p is the ionization potential and U-p is the ponderomotive energy. At large R, this extended cutoff is shown to be related to the nature of electron transfer, whose direction is shown to depend critically on the carrier-envelope phase (CEP) of the ultrashort pulse. Constructive and destructive interferences in the HHG spectrum resulting from coherent superpositions of electronic states in the H+-H-2(+) system are interpreted in terms of multiple electron trajectories extracted from a time profile analysis.