Two-color double resonant multiphoton ionization of nitrogen and the LIF detection of nitrogen molecule ion (1+) produced by multiphoton ionization

Highly excited states of the N2 molecule around 104,000 cm have been measured by two-color double resonant MPI via the a II/sub g/ state in a supersonic free jet. The (b' and c') Sigma/sub u/ states and the (b and c) II/sub u/ states were observed and the spectra show clearly the parity selection rule for the one-photon dipole transition. The relative intensities of the rotational branch of the II/sub u/ withdraws a II/sub g/ spectra show considerably mixing of the II/sub u/ states with the Sigma/sub u/ state. Also, laser-induced fluorescence detection was applied to measure the N2 ions produced by the (2 + 2) MPI through the a II/sub g/ state at room temperature. It was suggested that the produced N2 ion is rovibrationally highly excited.