High-resolution infrared and subterahertz spectroscopy of the v2Â =Â 1, v5Â =Â 1, and v3Â =Â 2 levels of 13CH335Cl

High-resolution Fourier-transform infrared spectra between 1235 and 1680 cm−1 and subterahertz spectra between 250 and 630 GHz of monoisotopic 13CH335Cl have been recorded and analyzed simultaneously, with all Coriolis, α-resonance, and l-type interactions in the polyad of the v2 = 1, v5 = 1, and v3 = 2 levels taken into account. Several α-resonances (Δk = ±2, Δl = ∓1) generating perturbation-allowed transitions have been assigned in the rovibrational spectra. These resonances enabled us to determine accurately and independently the ground state rotational and centrifugal distortion parameters A0 = 5.205 746 9 (55) cm−1 and DK0=8.4404(84)×10-5cm-1. Even HK0=8.527(39)×10-9cm-1, which is, however, correlated to higher-order α-resonance terms, was determined. With 51 upper state parameters varied, about 5800 rovibrational wavenumbers and more than 550 rotational frequencies pertaining to the excited vibrational states were fitted within their experimental accuracy.