Photodetachment microscopy of the P, Q, and R branches of the OH ^-(v=0) to OH(v=0) detachment threshold

A photodetachment experiment is performed on the v=0→v=0 OH ^- detachment threshold. The weak O and S branches provide a signal strong enough to make amplitude measurements on all five O, P, Q, R, and S branches possible, which are used to fix the formulas for their relative intensities. Photodetachment microscopy is applied to 15 different thresholds of the P, Q, and R branches. The quantitative analysis of the interference patterns obtained does not show any effect of the dipole moment of OH, but yields a new measurement of the rotational parameters of OH ^-(v=0) and of the electron affinity of the molecule. The new recommended value for the electron affinity of ¹⁶O ¹H is 14 740.982(7)cm ^-1 or 1.827 648 7(11)eV.