Sub-Optical-Cycle Attosecond Control Of Molecular Ionization By Using Fourier-Synthesized Laser Fields

We have investigated the combined positive and negative orientation-selected and yield-enhanced and suppressed molecular tunneling ionization of carbon monoxide by dual-phase control of femtosecond Fourier-synthesized laser pulses. To investigate the role of each harmonic light, two types of experiments have been performed: (1) two-color experiments using Fourier-synthesized laser fields consisting of a fundamental light and its second or third harmonics and (2) three-color experiments using Fourier-synthesized laser fields consisting of a fundamental light and its second and third harmonics obtained by changing each relative phase difference independently. Positive and negative orientation-selected ionization is induced by the omega + 2 omega laser fields, and yield-enhanced and -suppressed ionization is induced mainly by omega + 3 omega laser fields. The Fourier-synthesized omega + 2 omega + 3 omega laser fields concurrently enhance both positive and negative orientation-selected and yield-enhanced and -suppressed molecular tunneling ionization. The mechanism is discussed in connection with the sub-optical-cycle interference control of the laser waveforms.