Vibration-rotation spectra and molecular force field of methylene fluoride and methylene fluoride-d 2
Infrared spectra of CH 2F 2 and CD 2F 2 have been measured under a medium resolution. The vibration-rotation bands of CD 2F 2 fundamentals have been analyzed and the assignment for the fundamentals of CD 2F 2 is given. In addition, a number of overtone and combination bands are observed for CH 2F 2, which helps to clarify the vibrational assignment for CH 2F 2. A normal coordinate treatment has been carried out: The force constants in a modified Urey-Bradley as well as the general valence force fields have been determined, the vibrational frequencies and the centrifugal distortion constants obtained from microwave spectroscopy being used. The force constants of the methylene fluoride molecule are discussed in connection with those of the related molecules. Special features of the CH 2F 2 and CD 2F 2 spectra are also described.