Multiphoton excitation of mo lecules from many rotational states

Experiments on the vibrational excitation of molecules from different rotational states are described. The role of rotational relaxation in the course of multiquantum excitation of molecules is analyzed. It is shown that rotational relaxation has little effect on the absorption of powerful IR radiation by multiatomic molecules. It is concluded that molecules, in many rotational states, are effectively excited to high vibrational levels.