Calculations of the widths of some Feshbach resonances in CO−and NO−

The stabilization method of Taylor has been applied to calculations on the ${}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$ resonance in C${\mathrm{O}}^{-}$ at 10.04 eV. For this Feshbach resonance, an electron affinity of 0.22 eV has been obtained (experimental value: 0.35 eV). An ab initio calculation using this wave function and the "golden-rule" formula gives a width of 71 meV, compared with the experimental value of 45 meV. It is shown that the partial width increases as the energy of the electron decreases. In the II channels the main contribution comes from the $l=1\mathrm{}$ partial wave of the continuum electron. Some predictions are made for the widths of observed Feshbach resonances in N${\mathrm{O}}^{-}$.