Light-induced molecular potentials and temperature-dependent polarization of molecular vapours in intense resonant laser fields: I. Nonperturbative theory in quasi-classical approximation

The mechanism of creation of new electronic potentials and new vibration states in molecules irradiated by intense resonant laser fields is studied. The phenomena of selective orientation, delay of photodissociation, hardening and softening of intramolecular bonds are reconsidered within a model of overexcited molecule. It is shown that the laser-stimulated nonadiabatic dynamics of intramolecular motion can lead to unexpected alignment of molecules. The macroscopic polarization of molecular vapours irradiated by resonant lasers is analyzed. An experimental possibility to observe a temperature-dependent manipulation of the polarization is discussed.