Light-induced excited states in H-

We present a nonperturbative, fully correlated calculation of the structure of H^- in an intense laser field, based on the high-frequency Floquet theory. We show that, as the intensity increases at sufficiently high frequencies, the electron affinity manifests a peculiar behavior and can become substantially higher than its field-free value. Besides, H^- acquires excited states, some of which are doubly excited and nonautodetaching. At high intensities H^- undergoes stabilization, similarly to the H atom.