High-resolution infrared spectra and rovibrational analysis of the ν 12 band of propylene oxide.

The high-resolution infrared spectrum of the fundamental band ν 12 (ring breathing) of the chiral molecule propylene oxide (CH 3 CHCH 2 O) was recorded at room temperature and under jet-cooled conditions using a quantum cascade laser at 8 μm. The observed lines with quantum numbers J ≤ 55 and K a ≤ 21 were assigned to strong b - and c -type bands, and some low J transitions were classified as weak a -type transitions. The lines were fitted using a Watsons A-reduced Hamiltonian in the I r representation. From the rovibrational analysis the band origin as well as the rotational constants and four quartic centrifugal distortion constants were derived.