We present simulations of the orientation-dependent ionization yields of NO and OCS molecules in an asymmetric two-color (800/400 nm) linearly-polarized, phase-controlled laser fields (60 fs,1.26x1014 W/cm2 for NO and 26 fs, 7x1013 W/cm2 for OCS ). Real-time time-dependent density functional theory (RT-TDDFT) is employed using an atom-centered Gaussian-type orbital (GTO) basis with tuned range-separated functional (LC-PBE*) and a complex absorbing potential (CAP). The highest ionization yields are obtained at =50o and =120o for NO and OCS respectively, where is the angle between the permanent molecular dipole moment and the positive field direction. In both molecules, the ionization yield is highest when the field maxima points from the molecular center towards the O atom, i.e., the force on the electrons points from O→N or O→S, respectively. In NO, the butterfly-shaped peaks clearly resemble the highest occupied molecular orbital (HOMO), whereas OCS exhibits more multichannel character to the ionization. Furthermore, the shapes of the angle distribution exhibit a clear dependence on the relative phases of the two fields, which controls the field asymmetry.

Simulations of orientation-dependent ionization of molecules in strong asymmetric laser fields

ACS Spring 2022

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