The high resolution infrared bands ν1, ν2, ν4 and ν2 + ν5 of F37Cl16O3

The high resolution infrared spectrum of mono-isotopic F37Cl16O3 has been studied in the regions of ν1, ν2, ν4 and ν2 + ν5 bands, centered at 1060.20, 707.16, 1301.71 and 1292.15 cm−1, respectively. The ν1 and ν2 parallel bands are unperturbed so their analysis was straightforward and 3355 and 2433 transitions were assigned, respectively. The band origins, the rotational and centrifugal molecular constants in the v1 = 1 and v2 = 1 states have been determined, with standard deviation of the fits σ = 0.00019 and 0.00018 cm−1. The ν4 fundamental is affected by an anharmonic resonance with the ν2 + ν5 combination band. The kl > 0 sublevels cross at kl ⩾ 27 because of the opposite values of Aζ4z and Aζ25z. The anharmonic resonance constant W245F=2.7991246(358) cm−1 has been derived. The Δl = Δk = ±2 and Δl = 0, Δk = ±3 essential resonances have been found to be effective in ν4, while in ν2 + ν5 only the Δl = Δk = ±2 one was active. A total of 5721 transitions have been assigned, 25% of them belonging to ν2 + ν5. The rovibrational parameters and the interaction constants of F37Cl16O3 have been obtained. The standard deviation of the fit is 0.0006 cm−1, six times the estimated data precision. The equilibrium geometry of perchloryl fluoride has been determined from the Ae and Be constants of F35Cl16O3 and F37Cl16O3. Using the A0 and B0 constants of all the symmetric species the r0 geometry has also been derived.