The quenching mechanism of electronically excited Rydberg states of nitric oxide

Two photon excited fluorescence (TPEF) is used to measure the quenching cross sections of some NO Rydberg states by a number of molecules. The cross sections obtained are quite large, particularly for the C ²Π and D ²Σ states, often significantly exceeding the gas kinetic value. It is suggested that a mechanism common to many collision partners involves an ion pair intermediate. Using this model, the quenching efficiency is related to the electron affinity and to the weakest bond energy of the quencher.