Centrifugal distortion effects in the microwave spectrum of methylene cyanide

Abstract

The rotational spectrum of methylene cyanide has been measured up to J = 62 and a total of 82 b-type transitions have been obtained. These data have been analyzed with a semirigid rotor Hamiltonian to give accurate rotational and centrifugal distortion constants. The rotational constants are (in MHz) A = 20882.7537 ≠ 0.017, B = 2942.3003. ≠ 0.0031, C = 2616.7225 ≠ 0.0031 The quartic centrifugal distortion constants are (in MHz) Δ J (1.855455 ≠ 0.014) x 10 −3 Δ JK = (−6.79218 ≠ 0.027) x 10 −2 Δ K (8.621628 ≠ 0.013) x 10 −1 δ J = (4.892607 ≠ 0.016) x 10 −4 δ K = (6.7501 ≠ 0.29) x 10 −3 The uncertainties are twice the standard deviations in the constants obtained from the least squares analysis, and represent approximately 95% confidence limits.