The C-H bending vibration v4 of chloroform CH35Cl3

The infrared spectrum of the C-H bending vibration band nu(4) of chloroform around 1220 cm(-1) has been measured with a Fourier transform spectrometer at an instrumental resolution of 0.0018 cm(-1). An isotopically pure sample of (CHCl3)-Cl-35 was used. More than 3000 lines were assigned in the very congested spectrum. In the analysis the ground state rotational constants were fixed. The model included l (2, 2)-resonance and altogether 16 free parameters. The fit gave, for example, the molecular parameters nu(o) = 1220.338 03(5) cm(-1) alpha(4)(B) = 0.068 850(37) x 10(-3) cm(-1), alpha(4)(C) = 0.01237(17) x 10(-3) cm(-1), (Czeta)(4) = 0.0560362(18) cm(-1) and q(4) =0.17756 (15) x 10(-3) cm(-1).