(2+1)REMPI on molecular nitrogen through the (II)-state

The REMPI spectrum of molecular nitrogen, N2, was examined by tuning a focused ArF excimer laser beam in the range of 51 600–51 800 cm−1 and collecting the fluorescence from the Hopfield lines ( B 2 Σ u + – X 2 Σ g + of N 2 + ). The resulting spectrum was tentatively assigned at the two-photon level to rotational structure in the double a ″ 1 Σ g + – 1 Σ g + ( II ) potential energy well. To our knowledge this double well has not been seen experimentally before.