Analysis of the FTIR spectrum of pyrazine using evolutionary algorithms

The FTIR spectrum of pyrazine in the gas phase has been measured and analyzed using automated evolutionary algorithms. For the stronger bands, the rotational constants for ground and vibrationally excited states, the correct band types and in some cases centrifugal distortion constants could be extracted. Several hot hands have been identified and assigned by comparison to a cubic force field calculation at the MP2/6-311G(d,p) level of theory. Vibrationally averaged rotational constants for the excited bands can give a further guidance in the assignment of the vibrational bands.