Spectroscopic Study of the Π State of NaH.

In this study, the Π excited state of NaH has been experimentally studied for the first time. Pulsed laser-induced fluorescence excitation spectroscopy was used to investigate the Π electronic state of NaH. A total of 48 ro-vibronic transitions were observed, including within the - (0-0) and - (0-1) transition bands. Only one -state vibrational level was identified, and a series of PQR lines, with eight -parity and eight -parity sublevels (' = 0, ' = 1-8), were assigned. The level assignment was supported by a comparison of the experimental line positions with the calculations, the dispersed laser-induced fluorescence spectrum of the NaH Π → ∑ emission, and the V-type optical-optical double resonance spectra. The Dunham-type coefficients, the mean internuclear distance, the harmonic vibrational frequency ω, and the dissociation energies and of the Π state were determined.