Experimental Determination of the Oscillator Strength of the Violet System of OH

Abstract

The radiative lifetime of the A 2Σ→X 2Π transition of OH has been measured. The apparent lifetime is dependent upon the pressure of the parent molecule from which OH* is produced by electron bombardment. Extrapolation to zero pressure yields a spontaneous radiative transition probability of 0.99×106 sec—1 corresponding to an oscillator strength f= (7.25±0.5) 10—4. This value assumes that the electronic transition moment is constant over the (0, 0) vibrational transition. Utilizing Learner's values of rotation—vibration interaction an f value for the rotationless molecule and the (0, 0) band is f= (8.0±0.8) 10—4. The collisional quenching cross sections between OH* and water or methanol are 70×10—16 cm2 and 110×10—16 cm2, respectively.