Ultraviolet negative-ion photoelectron spectroscopy of the chromium oxide negative ion

The photoelectron spectrum of CrO− is reported, with four electron states of CrO detected. The 5Π ground state of CrO has an electron affinity of 1.221 ± 0.006 eV. An excited 3Π state is also observed, which lies 8600 ± 40 cm−1 above the ground state. Two additional states of CrO, believed to be triplets, are observed at energies of 4835 ± 80 and 7365 ± 40 cm−1, respectively.