Laser-driven dynamics in Rydberg states of argon cation

We present a theoretical model capable of describing the electronic dynamics taking place during and after the interaction of atomic systems with intense electromagnetic fields. The model is based on numerical solution of the time-dependent Schrodinger equation in a basis of electronic states constructed using the spin-orbit coupling scheme with the Hartree-Fock orbitals as a reference. We use the presented model to simulate a recent experiment measuring the interaction of argon with a sequence of intense ultrashort laser pulses (1.59 eV, 50 fs, ~10¹³ W/cm²) by means of the attosecond transient absorption spectroscopy. The absorption spectra shows two predominant transitions at 23.7 eV and 23.87 eV occurring between 3s²3p^{5 2}P, J = {1/2,3/2} and 3s²3p⁴(³P)4d ²D, J = {3/2,5/2} electronically excited states of argon cation. We demonstrate the possibility to control the electronic structure of the atom by manipulating the waveform of the applied driver field. An explanation of the underlying physical mechanisms is given. The developed methodology is general and as such applicable to describing the electronic structure and dynamics in arbitrary atomic systems.