New infrared integrated band intensities for HC3N and extensive line list for the v(5) and v(6) bending modes

The infrared spectrum of cyanoacetylene (also called propynenitrile) has been investigated from 400 to 4000 cm(-1) at a resolution of 0.5 cm(-1). Integrated intensities of the main bands and a number of weaker bands have been obtained with an uncertainty better than 5%. Inaccurate values in previous studies have been identified in particular concerning the intensity of the strong nu(5) stretching band at 663.2 cm(-1). Former results on the temperature dependence of integrated intensities have also been revisited. Synthetic spectra calculation has been performed for the nu(5) and nu(6) bands on the basis of the best available high resolution data. It has been shown that the GEISA line parameters for HC3N are not sufficient to reproduce the band intensities and some hot band features observed in our experimental spectra at room temperature. As a first step, the model spectra has been improved by including a number of missing hot subbands and by calculating accurately the hot band relative intensities. Finally, a perfect agreement between calculated and observed spectra was achieved on the basis of a global analysis of HC3N levels up to 2000 cm(-1) combined with the new integrated intensity measurements. A new extensive line list for the nu(5) and nu(6) bending modes of HC3N has been compiled. (c) 2007 Published by Elsevier Inc.