The perpendicular fundamental x5 of chloroform 12CH35Cl3: high resolution infrared study of the x5 band together with the millimetre-wave rotational spectrum

The infrared spectrum of the perpendicular fundamental x5 of chloroform around 776 cm-1 has been studied by applying two high resolution methods. A short range from the central part of the spectrum was measured with a diode laser by using a cold jet sample including chloroform in natural isotopic abundancies. More than 100 rotational lines of 12CH35Cl3 could be assigned. The whole band region was measured by a Fourier transform spectrometer at a resolution of 0.0010 cm-1. In this case an isotopically pure sample of 12CH35Cl3 was used. Starting from the results of the diode laser investigation more than 2000 lines could be assigned with Jmax = 91 and Kmax = 58. In addition to the infrared spectra, millimetre-wave lines also were measured. A total of 58 lines corresponding to J values 22, 23 and 35 at the excited vibration state x5 = 1 were assigned and analysed. All the data from three different spectra were simultaneously fitted and, for example, the results x0 = 775.961 50(3) cm-1, B5 - B0 = -0.180 171(22) x 10-3 cm-1, C5 - C0 = -0.170 57(15) x 10-3 cm-1, and (C‘)5 = 0.047 5294(11) cm-1 were obtained.