Infraredndash;infrared double resonance in a supersonic molecular beam: Accurate determination of the cross section of collision induced rotational transitions in state selected NH3

摘要

A method of infraredndash;infrared double resonance in a nozzle beam is developed for the study of elementary processes of molecular collisions. A spectroscopic method to characterize the molecular states in the beam is also described. The NH3molecules are prepared in a kinematically and also spectroscopically lsquo;lsquo;purersquo;rsquo; state and then are subjected to collisions with various species of target molecules such as NH3, CH3F, CH3Cl, and N2O. A simplified calculation of the cross sections based on Andersonndash;Tsaondash;Curnutte theory can give a fairly good reproduction of the measured values. The elimination of a systematic error in the total cross section measurements is discussed.