High Resolution Infrared Spectrum of the C-F Stretching Mode of CH2 F37 Cl.

Diode laser spectra of CH2 F37 Cl (95% isotopically pure sample) have been recorded in the 9.4 μm region characterized by the nu4 fundamental. The spectral analysis allowed the assignment of more than 3700 transitions with J </= 92 and Ka </= 16 of the expected a /b -hybrid structure. The nu4 fundamental, whose origin is at 1067.7140 cm-1 , mainly interacts through a - and b -type Coriolis coupling with the nu9 fundamental located at lower wavenumbers near 1002 cm-1 . Local effects arising from Fermi resonance with nu5 + nu6 have been observed for the K a ' = 14 level. An effective set of upper state molecular constants was determined by fitting the less perturbed transitions to the Watson's A-reduction Hamiltonian in the Ir representation. Due to the second-order a -type Coriolis resonance, a number of perturbation-allowed transitions of nu9 were observed and assigned near the avoided crossing. Using a suitable program, we experienced a two band system analysis which produced the molecular constants of the v 4 = 1 and v 9 = 1 states along with the interaction parameter. From spectral simulation of nu4 , the |Deltaμa /Deltaμb | dipole moment ratio was estimated to be 1.8 +/- 0.2.