Rotational analysis of the A2Σ(v=1,2)+ − X2Π(v = 0) electronic bands of 15N18O

Deep-UV spectra of 15N18O have been recorded using cavity ring-down spectroscopy in the 205-216 nm region. The rotationally resolved spectra have been assigned for a first time as originating from the v″ = 0 X2Πr states toward v′ = 1 and 2 vibrationally excited levels in the upper A2Σ+ state. Nearly 400 individual line positions have been identified and included in a fit using an effective Hamiltonian method. Accurate ground state values as available from literature were used to derive rovibronic parameters for the A2Σ(v=1)+ and A2Σ(v=2)+ levels. This results in the following values: T1 = 46 427.21(2) cm−1, B1 = 1.79635(7) cm−1, D1 = 4.14(6) × 10−6 cm−1 and T2 = 48 636.04(2) cm−1, B2 = 1.78055(18) cm−1, D2 = 5.8(3) × 10−6 cm−1.