High-resolution coherent Raman spectra of vibrationally excited N-14(2) and N-15(2)

At an effective resolution of 0.001 cm-l. we measured coherent anti-Stokes Raman spectra of electrically discharged N-14(2) and N-15(2) in the electronic ground state X-1 Sigma(g)(+), specifically Q branches of bands with Delta nu = 1 up to nu' = 8 for N-14(2) and nu' = 7 for N-15(2), and O and S branches of the fundamental band of N-15(2). Account is taken of small wavenumber shifts due to pressure, AC Stark, and \chi\(2) interference effects. Separate fits of the Q-branch data of each isotopic variant, combined with selected data from the literature, yield term coefficients Y-kl and U-kl Or potential-energy coefficients c(j) that reproduce wavenumbers of measured spectral lines generally within 0.001 cm(-1). The value of the harmonic vibrational parameter omega(e) is 2358.5302(4) cm(-1) for N-14(2) and 2278.7913(7) cm(-1) for N-15(2). Efforts to combine spectral data of both isotopic variants to distinguish adiabatic and nonadiabatic effects arising from incomplete separation of electronic and nuclear motion in Nz were unsuccessful. (C) 1997 Academic Press.