Angular Dependence of Strong Field Ionization of 2-Phenylethyl-N,N-dimethylamine (PENNA) Using Time-Dependent Configuration Interaction with an Absorbing Potential.

Ionization of 2-phenylethyl-N,N-dimethylamine (PENNA) may lead to charge migration between the amine group and the phenyl group. The angular dependence of strong field ionization of PENNA has been modeled by time-dependent configuration interaction with an absorbing potential. The total ionization rate can be partitioned into contributions from the amine group and the phenyl group, and these components have very distinct shapes. Ionization from the amine is primarily from the side opposite to the lone pair and is dominated by the CH2 and CH3 groups. Similarly, trimethylamine (N(CH3)3), dimethyl ether (CH3OCH3), and methyl fluoride (CH3F) are also found to ionize primarily from the methyl groups. The predominance of ionization from the methyl groups can be attributed to the fact that the orbital energies of individual lone pairs of N, O, and F are lower than the CH3 groups. Because the angular dependence of ionization of the two groups is quite different, alignment of PENNA could be used to control the ratio of the amine and phenyl cations and potentially probe charge migration in PENNA cation.