Intensity distributions and isolated attosecond pulse generation from molecular high-order harmonic generation in H-2(+) driven by nonhomogeneous field

Intensity distributions and isolated attosecond pulse generation from the molecular high-order harmonic generation (MHHG) in H-2(+) and T-2(+) driven by the nonhomogeneous field have been theoretically investigated. (i) Generally speaking, the intensities of the harmonics driven by the homogeneous field can be enhanced as the initial vibrational state increases and much more intense harmonics can be obtained from the light nuclei. However, with the introduction of the nonhomogeneous effect, the enhanced ratios of the harmonic yields are decreased as the initial vibrational state increases. Moreover, the intensities of the harmonics from H-2(+) and T-2(+) are very sensitive to the nonhomogeneous effect of the laser field. (ii) The contributions of the MHHG from the two-H nuclei present the periodic variation as a function of the laser phase for the case of the symmetric nonhomogeneous field. However, for the case of the positive and the negative asymmetric nonhomogeneous fields, the left-H and the right-H play the dominating role in the MHHG, respectively. Moreover, as the angle between the laser polarization direction and the molecular axis increases, the intensity differences of the harmonics from the two-H nuclei are increased. (iii) By properly adding a half-cycle pulse into the positive asymmetric nonhomogeneous field, a supercontinuum with the bandwidth of 279 eV and an isolated 25 as pulse can be obtained. Published by AIP Publishing