Model simulation of coherent laser control of the ultrafast spin-flip dynamics of matrix-isolated Cl2

Starting from a diatomics-in-molecules Hamiltonian description of the valence states of Cl2 embedded in an argon matrix, classical trajectory simulations are utilized to establish a one-dimensional model for the photodissociation dynamics in three selected singlet and triplet states which is valid during approximately 150 fs after Franck–Condon excitations, i.e. before the Cl atoms approach the neighbouring Ar atoms. Using this one-dimensional model which describes the dynamics of the Cl–Cl bond length in the frozen argon lattice we carry out quantum dynamics simulations of the laser pulse control of the electronic spin with femtosecond time resolution and sub-Ångstrom spatial localization by means of simultaneous excitation of wave packets on the singlet and triplet potential curves starting from a vibrational superposition state in the electronic ground state. It is shown that the latter can be prepared by a pump–dump pulse sequence.