Photodetachment from OH- in a magnetic field

Photodetachment from OH- has been studied in a magnetic field. Ions stored in a Penning trap were photodetached by light from a tunable cw laser. The detachment has the predicted form: a series of asymmetric peaks resulting from the splitting of each rotational threshold into Zeeman and Landau levels. For the first time, sufficient resolution has been achieved to observe the shape of individual thresholds in a magnetic field. The observed positions and sizes of the peaks are in approximate agreement with calculations. However, an apparent discrepancy from the predicted spacings of thresholds was measured to be 0.100(42) cm-1. Possible explanations of this discrepancy are considered