ELECTRONIC QUENCHING AND ROTATIONAL RELAXATION RATE OF OH]2SIGMA+) PRODUCED BY VACUUM-ULTRAVIOLET PHOTODECOMPOSITION OF WATER

The quenching of fluorescence and the rotational relaxation of OH radicals in the electronically excited state (2∑+) have been measured in the presence of foreign gases such as H2, D2, N 2, CO, and He. The electronically excited state (2∑ +) of OH radicals has been produced by the photodecomposition of water vapor with a 1236-Å Kr resonance line. The intensity of the fluorescence of OH*(2∑+) has been measured in the (0,0) band. With the collision partner H2O or CO, a single collision is enough for the electronic quenching, and for other molecules, only a few collisions are sufficient. These phenomena have been explained by the long-range chemical force between OH* (2∑+) and foreign gases. The rotational relaxation of OH* (2∑ +) has been measured from the intensity change of K=20 of (0, 0) band. In OH-diatomic-molecule systems, the cross section is the largest for the collisions with Hz and about the same order of magnitude for those with D 2, N2, and CO. This can be explained by the simple classical model.