Interactions between vibrational polyads of propyne, H3C-CCH: Rotational and rovibrational spectroscopy of the levels around 1000 cm-1

The study of vibration resonance physics in propyne is based on experimental measurements of about 600 new rotational transitions between 495-590 and 700-760 GHz in excited vibrational levels v(5) = 1, v(8) = 1, v(10) = 3 and v(9) = v(10) = 1 with vibrational energies around 1000 cm(-1). The limits to the assignments and analysis were imposed by as yet unresolved anharmonic resonances with the states of the next higher polyad of levels lying above 1200 cm(-1), which affect the rotational states involved in transitions that would be measurable with non-vanishing intensities. Vibration-rotation spectra pertaining to the levels in question were studied in the regions 880-1150 cm(-1) (the nu(5) and nu(8) fundamental bands), 550-750 cm(-1) (the v(9) = v(10) = 1 <- v(10) = 1 hot bands) and 250-400 cm(-1) (the v(10) = 3 <- v(10) = 2 superhot bands). A simultaneous least-squares fit of both types of data provides their reliable but in the case of accurate rotational data not always fully quantitative reproduction. (C) 2009 Elsevier Inc. All rights reserved.