High-resolution FTIR measurement of the 2ν8 band of methylene fluoride (CH2F2)

A high-resolution (0.003 cm−1) infrared absorption spectrum of the first overtone of the fundamental mode ν8 of methylene fluoride (CH2F2) has been measured on a Bruker IFS 120-HR Fourier transform infrared spectrometer. More than 2000 ro-vibration transitions in the range of 2770-2900 cm−1 with J ⩽ 45 and Ka ⩽ 20 have been assigned in this B-type band centered at 2838.5 cm−1. Precise value for the band origin (2838.579799 cm−1) and centrifugal distortion constants up to third order (ΦJK, ΦKJ, and ΦK) have been obtained by fitting a total of 1474 unblended ro-vibration transitions (J ⩽ 45 and Ka ⩽ 13) of the 2ν8 band with a standard deviation of 0.00029 cm−1 using a Watson's A-reduced Hamiltonian in the Ir representation. Signature of perturbations with nearby states has been seen.