title: Vibration-rotation energy pattern in acetylene: (13)CH(12)CH up to 10 120 cm(-1).
abstract: All 18,219 vibration-rotation absorption lines of (13)CH(12)CH published in the literature, accessing substates up to 9400 cm(-1) and including some newly assigned, were simultaneously fitted to J-dependent Hamiltonian matrices exploiting the well-known vibrational polyad or cluster block-diagonalization, in terms of the pseudo quantum numbers N(s) = v(1) + v(2) + v(3) and N(r) = 5v(1) + 3v(2) + 5v(3) + v(4) + v(5), also accounting for k = l(4) + l(5) parity and e/f symmetry properties. Some 1761 of these lines were excluded from the fit, corresponding either to blended lines, for about 30% of them, or probably to lines perturbed by Coriolis for the remaining ones. The dimensionless standard deviation of the fit is 1.10, and 317 vibration-rotation parameters are determined. These results significantly extend those of a previous report considering levels below only 6750 cm(-1) [Fayt, A.; et al. J. Chem. Phys. 2007, 126, 114303]. Unexpected problems are reported when inserting in the global fit the information available on higher-energy polyads, extending from 9300 to 10 120 cm(-1). They are tentatively interpreted as resulting from a combination of the relative evolution of the two effective bending frequencies and long-range interpolyad low-order anharmonic resonances. The complete database, made of 18,865 vibration-rotation lines accessing levels up to 10 120 cm(-1), is made available as Supporting Information.
authors.affiliation: Service de Chimie Quantique et Photophysique CP160/09, Faculté des Sciences, Université Libre de Bruxelles, Av. Roosevelt, 50, B-1050 Bruxelles, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Robert
authors.forename: B
authors.initials: B
authors.lastname: Amyay
authors.forename: A
authors.initials: A
authors.lastname: Fayt
authors.forename: G
authors.initials: G
authors.lastname: Di Lonardo
authors.forename: L
authors.initials: L
authors.lastname: Fusina
authors.forename: F
authors.initials: F
authors.lastname: Tamassia
authors.forename: M
authors.initials: M
authors.lastname: Herman