First analysis of the 1-v″ progression of the Ångström (B1Σ+-A1Π) band system in the rare 13C17O isotopologue.

The 1-v″ progression of the Ångström band system, so far unobserved in the rare (13)C(17)O isotopologue, was obtained under high resolution as an emission spectrum using a high accuracy dispersive optical spectroscopy. In the studied region 22,700-24,500 cm(-1), 146 spectral lines were observed, among which 118 were interpreted as belonging to the 1-0 and 1-1 bands of B-A system, and the next 28 were interpreted as extra lines belonging to the 1-1 band of B(1)Σ(+)-e(3)Σ(-) intercombination system, also unobserved in the (13)C(17)O molecule so far. All those lines were precisely measured with an estimated accuracy better than 0.0025 cm(-1), and rotationally analyzed. As a result the following in the (13)C(17)O molecule were calculated for the first time: the merged rotational constants B1 = 1.790227(23) cm(-1), D1 = 6.233(47) × 10(-6) cm(-1), and ΔG1/2 = 2010.9622 (69) cm(-1) and the equilibrium constants, ωe = 2076.04(57) cm(-1), ωexe = 32.54(28) cm(-1), Be = 1.824678(15) cm(-1), αe = 2.2967(24) × 10(-2) cm(-1), De = 5.226(25) × 10(-6) cm(-1), and βe = 6.71(48) × 10(-7) cm(-1) for the B(1)Σ(+) Rydberg state, as well as the individual rotational constant B0 = 1.50485(78) cm(-1), and the equilibrium constants ωe = 1463.340(21) cm(-1), Be = 1.49902(12) cm(-1), αe = 1.7782(49) × 10(-2) cm(-1), De = 7.36(56) × 10(-6) cm(-1) for the A(1)Π state, and σe = 21,854.015(51) cm(-1), RKR turning points, Franck-Condon factors (FCF), relative intensities, and r centroids for the Ångström band system. With the help of the strong and vast A(1)Π (v = 0) ∼ e(3)Σ(-) (v = 1) interaction, the experimental parameters of the e(3)Σ(-) (v = 1) perturbing state were established in the (13)C(17)O molecule for the first time.