High resolution FTIR spectra and analysis of the ν11 fundamental band of 13C6H6

A high resolution FTIR (apodized instrumental bandwidth 0.004 cm−1 FWHM) spectrum has been measured for the isotopically pure benzene molecule 13C6H6 in the range 600–850 cm−1. Accurate molecular constants have been obtained for the fundamental vibration ν11 (Wilsonʹs notation, which is used here; ν4 according to Herzbergʹs notation) of 13C6H6 with band center at 672.12930(5) cm−1. Several hot-bands have been analyzed as well. Improved ground state constants have been deduced from a fit of ground state combination differences.