High resolution FTIR spectra of the ν9 vibrational band of cis-rotamers HCOOH and H13COOH

High resolution FTIR spectra of the ν9 vibrational band of cis-rotamers for both parent and 13C isotopically substituted formic acid molecules have been observed and analyzed. Rotational and centrifugal distortion parameters of the 91 vibrational states have been obtained or improved. The band centers for cis-HCOOH and cis-H13COOH have been determined to be 493.4205092(73) and 492.938656(19) cm−1, respectively.