Rotational photodetachment spectroscopy of the SeH- ion

Individually resolved rotational photodetachment thresholds have been observed for SeH- ions in a magnetic field. The observed photodetachment cross section exhibits structure due to the cyclo- tron levels of the detached electron in the magnetic field. The electron affinity of SeH and the rotational constants of SeH- are determined from the measured rotational threshold energies. In addition to the high-resolution individual rotational threshold spectra, low-resolution spectra, for which the rotational band structure dominates, are obtained. These low-resolution spectra are used to assign rotational quantum numbers to the individual thresholds. The electron affinity of SeH is found to be 17?5.17(20) cm-1, and the rotational constants of SeH- are found to be B=7.7289(46) cm-1 and D=3.33(9)×10-4 cm-1.