Keldysh-scaling in the waveform control of the dissociative ionization of D2

Here we applied this unique light source to study the waveform control of the dissociative ionization of the prototype molecule D₂ at 2.1 μm at an intensity of 6.2 (± 1.5) x 10¹³ W cm^-2 . The longer wavelength not only moves the ionization deeper into the tunneling regime, but furthermore allows for the control of the dissociation at large internuclear distances. We observed a very high degree of the directional ejection of D⁺ fragments along the laser polarization axis for kinetic energies of the generated ions corresponding to the bond softening channel and almost vanishing asymmetry at high energies. These results are in contrast to earlier studies at 760 nm, where recollisional excitation was a vital element in the mechanism responsible for the observed phase control and caused high asymmetries in particular at high kinetic energies.