A long path cell for the fourier spectrometer Bruker IFS 120 HR: Application to the weak nu(1)+nu(2) and 3 nu(2) bands of carbon disulfide

The construction and properties of a White cell connected to a Bruker IFS 120 HR spectrometer are described. The maximum path length attainable is about 200 m. The cell and its use in accurate measurements where the calibration is performed with the aid of CO2 laser lines in absorption has been tested with the weak bands nu(1) + nu(2) and 3(nu 2) of CS2. From the ground state combination differences of these bands, new, more accurate rotational constants were derived: B-0 = 0.109126043(50) cm(-1) and D-0 = 1.17678(31) x 10(-8) cm(-1). The bands were fitted with a standard deviation of 4.8 x 10(-5) cm(-1) by using a model, where the I-type and Fermi resonances were included. The intensities in the bands were strikingly perturbed. These anomalies were explained and simulated with the Herman-Wallis effect. (C) 1997 Academic Press.