Role of the mode composition of laser radiation in the case of pulsed infrared excitation of molecules

A comparison is made of the results of a theoretical description of the excitation of a "two-level molecule" using various models of a laser field and the results of experiments on collisionless excitation of NH₃ and SF₆ by multimode CO₂ laser radiation. The importance of the role of the mode structure of the laser field is demonstrated.