Controlling molecular harmonic generation from H₂⁺ by using half-cycle pulse

The investigation on the control of the molecular harmonic generation from H₂⁺ has been presented by solving the time - dependent Schroedinger equation. Calculated results show that when the laser field is larger than zero, the contribution from the negative - H to the harmonic spectrum plays the main role in harmonic generation; while when the laser field is smaller than zero, the harmonic emission from the positive - H plays the dominating contribution to the harmonic spectrum. Further, by properly adding a half - cycle pulse, the intensities of the harmonic spectra from the positive - H and the negative - H can be effective controlled. Finally, by superposing a properly selected harmonics, a 46 as pulse can be produced. The investigation is helpful to control the molecular harmonic generation and to produce the attosecond pulse. (authors)