Mechanism of the excitation of high vibrational–rotational states and dissociation of polyatomic molecules by an infrared field

The physical mechanism of the excitation of high vibrational–rotational states and dissociation of polyatomic molecules in a strong infrared field is discussed. It is shown that when the level density is high, the process can be quantitatively described using a system of rate equations. For simplicity this system is replaced by a diffusion-type partial differential equation. The solution of this equation is applied to estimate the threshold radiation pulse energy needed for dissociation.