Oscillator strengths in the 2 ∑ +—2 Π band system of OH by the hook method

The hook method has been used to obtain oscillator strengths for twenty lines in three branches of the (0, 0) band of the 2∑+-2Π system of OH. It is found that vibration-rotation interaction decreases the effective f-value for this band by about 7% over the first ten lines of each branch. The absolute f-value obtained for the rotationless molecule is f00 = (14·8 ± 1·3) x 10-4. Although this falls within the range of previous measurements, it is nearly twice as large as the value hitherto considered most probable. For the (1, 0) band, in which vibration-rotation inter­action could not be measured, the absolute oscillator strength is found to be (8·9 ± 1·7) x 10-4, giving for the relative oscillator strengths the ratio f10/f00 = 0·60 ± 0·10.