Single and two-photon infrared laser spectroscopy of selected negative ions

Atomic negative ions that primarily utilize resonantly enhanced two-photon detachment or single-photon tunable laser spectroscopy are investigated. A search for the 6s6p state of Cs^-, which is of opposite parity to the ground state is conducted yielding evidence for an unbound level. The M1 transition in Te^- which verifies the feasibility of using magnetic dipole transitions is demonstrated. Finally, a brief progress report on the ongoing tunable infrared laser experiments aimed at large improvements in binding energy determinations in a variety of negative ions, including those of Si, Ni, Cu, Pd, and Co is presented.