Spectroscopic studies of negative molecular ions are proposed using a negative ion beam and a coaxial infrared laser beam from a color center laser. Vibrational-rotational transitions are induced between the internal states of the ion, and the excited ionic state autodetaches producing a fast (keV) neutral which is then detected. It is proposed to measure the vibrational-rotational transition of negative ions with sufficient resolution to observe hyperfine structure, and detect metastable states in the autodetachment continuum. It is also proposed to perform photodetachment studies of atomic anions near threshold, measuring the electron affinity of the atom and testing the range of validity of the Wigner law for the behavior of the cross section near threshold. The results are relevant to spectroscopy, quantum chemistry, and to studies of laboratory and terrestrial plasmas.
